IT Rotary Engines

[Ron Earp]

I was looking through the GCR, specifically the ITCS ITS section, and noted that there is no hard data on the RX7 13B motor with respect to critical power producing specifications – mainly port sizes. Piston engines listed in the ITCS have the majority of the key specifications listed and, for the most part, some of them can be fairly accurately checked at the track with a micrometer or even a good measuring rule. Valve diameter along with bore/stroke are easily checked and with a few more simple tools the compression ratio can be measured. But with a GCR in hand there are no specifications on a rotary engine that can be evaluated.

In the paddock I have heard it rumored that there is no definite port size on the 13B rotary engine and thus a specification in the ITCS cannot be listed. I might certainly believe that some castings have a more desirable specification but then the dimensions of this particular port should be stated since it would be the maximum size. As it stands there is no way to inspect a 13B at the track unless you have a factory casting from Mazda. And even then there would be suspicion cast upon the bearer of the factory part that might nullify an inspection result.

If it is indeed true that there is no factory specified port sizes on the rotary engines then we’ve got a problem as the cars won't have confining specifications on a critical aspect of the motor.

If there is a factory specified port size it would seem to me that we might want to get some port size dimensions put into the GCR in the form of text, or if some sort of irregular shape, an engineering drawing of the port(s).

[GKR_17]

What is needed are 'lollipops'. The SE div had a set for the 12a a while back, don't know if they're still in use.

We have a set for the 13b, but the stewards would not even look at them when they were provided in a protest (at the ARRC). In that case they only allowed visual inspection of the ports, just how much is that worth?

Where no specs are available, the GCR requires the club to determine the allowable specs. That should clearly apply here.

[GKR_17]

On another note... the ITCS allows the rotary to be bored .040 over. Clearly that's ridiculous, but I got a lot of rolled eyes when I suggested it be fixed.

[JeffYoung]

We were told there was no way to "lollipop" the 13b. Don't remember why, but that was the word. You physically have to take it apart and compare what is in the protested car to a stock housing.

Mr. Eckerich has a new in the box sealed up rotor housing. I think we just take a measurement, get it confirmed, and ask that it be added to the notes/spec line on the 13b.


What is needed are 'lollipops'. The SE div had a set for the 12a a while back, don't know if they're still in use.

We have a set for the 13b, but the stewards would not even look at them when they were provided in a protest (at the ARRC). In that case they only allowed visual inspection of the ports, just how much is that worth?

Where no specs are available, the GCR requires the club to determine the allowable specs. That should clearly apply here.

[Jeremy Billiel]

Unforunately guys who run the 13B have been running with no fear or any inforcement for years.

[JeffYoung]

Not true down here. One legal RX7 has managed to keep the others in line, and that is much appreciated.

Just checked -- the 89-91 motors (the S5 that I think everyone runs) has exhaust baffles that prevent use of the lollipop.

[GKR_17]

Just checked -- the 89-91 motors (the S5 that I think everyone runs) has exhaust baffles that prevent use of the lollipop.

That depends on how the lollipop is made. As I said, we have a set (made from castings with the baffle).

[Ron Earp]

We have a set for the 13b, but the stewards would not even look at them when they were provided in a protest (at the ARRC). In that case they only allowed visual inspection of the ports, just how much is that worth?
.

Doesn't surprise me that the tech folk wouldn't want to use lollipops that you provided. Or a stock rotor housing. That's the core of the problem - only the party competing against the rotary that is torn down is interesting in having stock parts or lollipops. But, those items would be ignored in a protest due to conflict of interest.

Visual inspection - not much use. The ITCS says:
2. Rotary engines (only)
a. Any porting or polishing is prohibited.

But in this day and age it wouldn't be too hard to port and make it look like it was never touched, at least for a visual inspection.


From the ITCS on specs:
Where factory specifications are absent or unclear, e.g., cylinder head thickness and/or combustion chamber depth, etc., the Club may establish an acceptable dimension and/or allowable tolerance from stock.

With my inline six I can probably have the head off, displacement, valve size, and a rough compression check completed in under three hours. Seems it should be possible to perform similar performance checks on a rotary engine.

[JeffYoung]

And, apparently, one cheat is to use a Turbo rotary housing which is bigger, but looks stock and not ported.

The answer to this one is simple guys. We get a 13b housing new in the box, measure it and provide the specs.

[lateapex911]

The answer isn't that simple.
Jeff, "we" can't do that...nor can Steve provide the part..conflict of interests arise in both conditions.

In a protest of a piston engine, even if the GCR says 30mm valve size, the protestee can appeal and say it's wrong, and the GCR very well may be, and the protest will be overturned when the research concludes the listed size is a mistake or typo or whatever. Shop manuals at the track will override the GCR, or cause enough doubt as to cause the Protest stewards to not render a decision at the track.

Your "issue" appears to be a matter of timing. In a 13B teardown (12A too), the part is confiscated, and a stock one is procured by the Stewards from Mazda, and compared to the part in question. I'm assuming that you don't like the lag time involved, because rotaries CAN be protested in this manner just as any piston engine can. Remember, the port is akin to a cam, and cams go out for measuring against stock examples that independent parties (SCCA Stewards) procure when a cam is protested.
(An intake port is located on the sideplate and looks like a liver shaped swimming pool, kinda. It's not as simple as measuring a circle. Lollipops are for exhaust only, and don't measure all the parameters of the port anyway)

Now, SCCA DOES have certain cam profiles on file, so there are some cases where it's easier and quicker than having to get the part and then measure it.

You COULD request that:
- SCCA Tech purchase a stock 13B side plate and housing and maintain them in stock for future protests. SCCA might be willing to pay, or Mazda might be willing to donate.
- You could convince your regions tech staff to do the same. Funding is an issue.
-Or, you could arrange for the Regions tech staff to procure the part, and then pay an independent lab (one with no POSSIBLE conflict of interest) to measure the shape via CAD and store the profile in the Regions files. Once you have the measurements (and it's not just a 2D measurement either) you can return the part and disseminate copies of the data easily and quickly. Now, measuring a protested piece would need to be accomplished by an independent firm having the proper tools, or by the Regions staff if they had the proper tools.

No matter what, i think, rotary teardowns aren't trivial, and you just have to ignore the seemingly obtuse aspects and forge ahead.

[JeffYoung]

With all due respect, I think it is, and has to be, much simpler than that. Ron's cite to the GCR gives us the answer. We get a 13b housing (the suckers are not cheap though, $650 each front and rear from Mazdatrix), measure the ports and add that to the spec line. Or SCCA does.

And t I'm not sure why SCCA Tech has to do that. We (on the ITAC) "determine" valve sizes, compression, etc. via internet searching.

I also think you are missing the point. We just want a spec for the ports on a 13b in the GCR for future reference. So no one has to haul stock 13b housings to the track for a protest. It is honestly pretty silly, and at least to this guy unecessary, that a rotary has to be torn down to check port sizes.

[Ron Earp]

The answer isn't that simple.
Jeff, "we" can't do that...

Well then we need to find a "we" that can.

Jake, none of what you write or suggests concludes with specs getting into the GCR. The goal here is to get specifications into the GCR.

As far as the cam analogy it is, as I am certain you know, a bit more complicated. The port size provides the "cam lift" and the port size provides the "valve diameter". So, suggesting a housing is like a cam and therefore has to be sent to Topeka for inspection doesn't quite hold water.

Port specifications should be in the GCR. Else I'll go to work on getting my 260z specs out of the GCR so that you rotary guys have to haul a head around to tear me down. You don't want that. Those heads are heavy. :-)

[Greg Amy]

I have a dog in this fight, given I've raced in ITS and probably will again. However, on the other side I know a lot of this engine in general, as I was one of Racing Beat's best customers in the 80's (RX-3 SP).

Bottom line: numerical specs don't cover it.

A Wankel's port are all about airflow (duh), but it's not just size, it's shape, it's location, it's flow direction. I found out REAL QUICK that a little bit goes a loooong way on a Wankel, and done correctly it's very tough to catch a little bit.

I am not familiar with "the lollipop" though I've heard it discussed here; can anyone offer some links/pictures on it? But I suggest the only way you're going to catch rotary cheating is with some kind of shaped plug that is located relative to a common point in the rotor housing, built in such a way as to mimic the post shape, size, and location.

But I just don't think you're going to be able to publish numerical specs that some scrutineer out at the track can use to verify legality; you're going to have to distribute specialized go/no go gauges that take out all the doubt...

GA

[mbuskuhl]

We get a 13b housing (the suckers are not cheap though, $650 each front and rear from Mazdatrix), measure the ports and add that to the spec line. Or SCCA does.



Those are the rotor housings, you'll need the side and center irons as well for the intake ports.


And, apparently, one cheat is to use a Turbo rotary housing which is bigger, but looks stock and not ported.



The turbo rotor housing does not have an exhaust diffuser like the NA rotor housing. Simply pull the header and look for the diffuser.

[GKR_17]

Doesn't surprise me that the tech folk wouldn't want to use lollipops that you provided. Or a stock rotor housing. That's the core of the problem - only the party competing against the rotary that is torn down is interesting in having stock parts or lollipops. But, those items would be ignored in a protest due to conflict of interest.

That is quite true. However at the time, we believed that if we could show the protested parts differed from our stock examples, that would be sufficient to have the club confiscate the parts until it could be determine which is correct. The SOM's were not interested however.


Lollipops are for exhaust only

Maybe the ones you've seen. They can be made for the internal ports as well. Like I said, we have a SET.


Port specifications should be in the GCR. Else I'll go to work on getting my 260z specs out of the GCR so that you rotary guys have to haul a head around to tear me down. You don't want that. Those heads are heavy. :-)

I haven't researched the Z's thoroughly, but I thought that was already a problem, no cam specs in any official documentation. That's a problem with a lot of cars actually, our old Suzuki Swift had nearly no specs in the factory workshop manual.

[JeffYoung]

Greg, do you think port dimension specs would at least help/be a start? Or worthless?

Grafton, Z car cam specs are pretty easy to get, there was just confusion as to what came with what car. It's now pretty clear that the "A" cam was 240z only, and the "C" cam 260z only. The cheat back in the day was to use the C cam in the 240 motor, and arguments were made that it came in the car. It did not.

It is true though that a lot of cars it is hard to find cam specs for. Irish Mike will flat out tell you he believes there is no written cam spec for the 190E 2.3-16.

[lateapex911]

Jeff, that's what I'm saying...Greg is right, it's not a question of a spec...you can't measure it without a 3D CAD model. XYZ axis referenced off a static location.

And you'll need the inner and outer plates, not just the housings. Think about a liver shaped swimming pool. where the bottom just keeps going to the injection system. THAT's the shape you need to 'measure'.

It's not as simple as saying it's 30mm x 24mm with X radii for corners.

here's a port, note that you can change the flow in many ways other than changing the peripheral shape. http://img504.imageshack.us/img504/2619/port1uz2.jpg

[Greg Amy]

Greg, do you think port dimension specs would at least help/be a start? Or worthless?
I'd hate to say "worthless" but I'd certainly characterize it as "unrealistic". Since it's a three-dimensional shape, you'd have to spec not only the specific measurement, but its specific location; any self-respecting scrutineer would be hard-pressed to be able to be that accurate.

I'd like to see one of these lollipop tools and learn more about their source.

[Andy Bettencourt]

I am sure STeve does too but we have a shit-ton of stock housings that aren't usable anymore at the shop that the ports could be measured and documented.

But to reiterate, missing baffles is a red flag of epic proportions.

[Ron Earp]

Grafton, Z car cam specs are pretty easy to get, there was just confusion as to what came with what car. It's now pretty clear that the "A" cam was 240z only, and the "C" cam 260z only. The cheat back in the day was to use the C cam in the 240 motor, and arguments were made that it came in the car. It did not.
.

Interestingly enough the GCR has the 260Z as 73-74. I never knew that. The rest of the world thinks the 260Z was a 1974 only model year for the US......wonder why it overlaps with the 240Z of 1973?

Stock rotor housings, yes, lets get some and measure them up. We could cast molds from the ports and have lollipops made up. Got one friend who is into casting stuff (as I bet some folks here are) and another who runs a big CNC shop. Between the two of them I bet we could get a mess of lollipops made for not extravagant costs. Then we'd all have lollipops that could be ignored in the tech shed.

The problem I see is that without some specs that are recognized in the GCR RX7 protests are paper tigers.

[lateapex911]

The problem I see is that without some specs that are recognized in the GCR RX7 protests are paper tigers.

Ron, with due respect, no they are not "paper tigers". They just need to be done through the proper channels. Get stock housings through independent sources (Mazda -> stewards) and you're good to go. Heck if timing is an issue, contact the Steward before the race, provide the $ and have them ordered early and in the stewards possession. Once used, return them, net cost will be the restocking charge, and I'd bet Mazdaspeed would waive that.

If I'm a rotary guy, and i get protested, I know I'm legal, but if somebody says, "Hey, this lollipop doesn't agree," I'm going to want the paper trail, and it better not start at a competitors 'stock part". Even if the stock part is 1000% legal, the deal is going to smell. So, if you're going to do a lollipop, make sure the process is 100% above board and completely neutral. In other words, Stewards buy the part, Stewards get teh measuring/machining/molding etc done, and Stewards stamp the part and maintain the inventory. If a competitor holds/supplies it, it is worthless. It has to be.


I agreet that trying to quantify the part is critical, but again, the GCR isn't the absolute last word. it can be wrong. Beyond that, how are you going to put 3D CAD specs in it?

[C. Ludwig]

The intake and exhaust ports are defined in terms of crankshaft position. This is the most precise way to define the port and any scrutineering should be based on this approach. More on this later. One glaring example of why a simple lollipop would not work is the, already mentioned, 87-91 turbo center iron. The overall size and shape of the turbo primary port (the port present in the center iron) is essentially the same as that of the NA center iron. However, the entire port is shifted toward the closing line without a change to the opening line. What you end up with is a port that is essentially the same "size" but provides a 10* later closing and 10* more duration. Externally, the turbo iron is indistinguishable from the 89-92 NA iron. A lollipop would likely pass the turbo iron.

IMO, a lollipop would fail to tell the whole story of the exhaust port as well. To begin with, the exhaust port of the NA and turbo rotor housings is the same dimensionally. The only difference between the two in regard to this discussion is the diffuser that was added to the NA engine from the factory to help quiet them down. Pic below.

http://www.aaroncake.net/misc/rebuild/44%20-%20Stock%20Exhaust%20Port%20Inside%20View.JPG

This is obviously a pic of the internal side of the port. The external side of the port is much larger than the internal. Think of the runner as a megaphone. In the first place, the port size and timing of the stock exhaust port is very good for an IT engine. Not much is going to be gained from exhaust porting, or the removal of the diffuser sleeve. Secondly, if someone wanted, they could easily make handy modifications to the stock bevel around the exhaust port to encourage it to breath while still retaining the basic shape and satisfying a lollipop test. Again, the port is described by Mazda in terms of crankshaft angle, and that would be the best way to scrutineer the engine.

At the end of the day, it's extremely easy to tell if an engine has been ported on the intake side. The primary and secondary runners are all rough cast. Any tooling of this cast surface is very obvious when the intake manifold is removed. The photo that Jake provided above shows a common street port. The closing edge of the port simply can't be modified without it being pretty obvious to the naked eye when the intake manifold is removed. No bore scope needed, just a flashlight and a keen eye. The open line (the part of the port shaded in blue in Jake's pic) could be manipulated, but it would be very hard to get that past a trained eye. The ports are rough cast by Mazda and then the final shape of the port is cut with a CNC process. The mill leaves a very clean mark all the way around the circumference of the port. I'll go out on a limb and say it's impossible to replicate this milling by hand and fool a trained eye. It's also impossible to recreate this line with a CNC mill and alter the port dimensions by any great degree without disturbing the rough casting. Again, the opening line of the port could be moved back (opening the port sooner and creating greater duration) but it would be very difficult to replicate the accuracy of the CNC cut by hand. It could be done but it would be real tough.

The aux secondary port (sometimes referred to as the 5th and 6th ports) are smooth bored from the factory for fitment of the aux port valves which are typically, legally removed as part of an IT build. The actual port dimensions of the aux secondary ports are already very radical in terms of timing in regard to crankshaft location. There isn't anything that's going to be gained from going bigger on these ports.

What are the port dimensions?

Primary port (center iron) opens at 32* ATDC and closes at 40* ABDC
Secondary port opens at 32* ATDC and closes at 30* ABDC
Aux Secondary port opens at 48* ATDC and closes at 80* ABDC

IMO, what you guys need in the paddock is a trained eye. There are cheater engines out there. And you'd never believe how easy it would be to catch them with the naked eye.

I have damaged stock housings you guys can have to measure to your hearts content if someone will pay shipping and handling.

[Ron Earp]

Ron, with due respect, no they are not "paper tigers". They just need to be done through the proper channels.

Well, as one who just went through this process I have some data that suggests that they are indeed paper tigers of a sort.

IT is grassroots amateur racing. Not semi-pro, little league, or anything like that, but pure fun amateur sport. Along those lines there should be a way to check some basic specifications of a rotary engine without resorting to master templates locked in a vault and what not.

You and I go race. You go eight seconds a lap faster than you went last month and set a new track record. I decide to protest you, the tech guys set the bond, I pay it, and your car gets pulled down in the tech shed by Joe Average SCCA Technical crew.

If you have a piston engine the tech guys can determine a fair amount about your engine:



With a dial indicator, a tool I have in my trailer, we can determine cam lift to a reasonable accuracy.
With a caliper, another tool I have in my trailer we can very accurately measure displacement.
With the same caliper we can very accurately measure valve sizes.
And, in some regions a buret, dye, plate, and grease are available that would allow us to determine compression to a reasonable degree (probably to within a couple of tenths which isn't bad for trackside work and will catch gross levels of cheating).

But, if you are running a rotary engine one of two of things might happen:



If the engine is torn down in tech at the track what are the tech guys going to look at? This protest wasn't planned ahead, so no factory sealed parts from Mazda are on hand, and if they were they might not even be accepted by tech due to conflict of interest. There are no specs in the GCR, nothing to measure. Tech guys eyeball some ports, some expert says looks factory or doesn't look factory, and there you go.
The teardown bond is set high because the engine has to be sent off for inspection. Protest doesn't go occur because the protester(s) can't afford the bond.


The way things are a rotary engine can be a cheaters paradise. Fortunately cheating isn't rampant in IT but it'll be damn hard to identify illegal rotary engines unless you've planned way ahead and gotten the right people to the track at the right time.

[lateapex911]

Ron, one thing I learned, assume nothing...
When we did our protest, the techs couldn't measure compression*, but noted that the head hadn't been cut, so therefore, it must've been "OK". So that part of the protest was denied, and the guy was deemed legal. (last minute outside of the Protest committee stewarding saved the day, but...)

So, I had assumed they would be able to do some basic stuff, but it wasn't so basic. yea, it would be NICE to be able to show up and get answers, but, I've found prepping far in advance (like racing) yields the best result....even when things seem simple.

*This was a result of tech not having the proper tools...tools that we had. And word got out that the techs were looking for them, and we offered ours. Denied of course, conflict of interest. Our suggested neutral sources, for facilities and tools, also denied.

In your scenario, #1 should never happen, for the reasons you illustrate.
#2, teardown bond shouldn't increase that much for an offsite inspection. The engine still needs to come out and be torn down. (In reading your comments about your recent protest, I've inferred the bond was very very high, and that seems not quite right to me). Huge bonds will occur in many cases, of course. (tear into a Porsche 911 to weigh the crank? Ugg) It sounds like this one was out of line, but, that's a hunch on my part, and don't quote me on it!

I think the issues you have are not unique to the rotary, but will come up in any number of protests. It's a balance in the system....maybe not the right balance, but it tries to protect against vexatious actions and ensure legitimacy. But it also makes the hurdles very high.

[Andy Bettencourt]

Ron, (example)

You have uber-light forged pistons in your Z. I write a good protest asking for displacement, compression, cams and piston compliance - all checked.

Please tell me how much easier it will be to validate all that on your car (or Jeff's) than it would be to do this:

Have a stock set or rotor housings to compare to on hand. You and the PC compare. If a reasonable difference is spotted, you go through with the protest by sending the motor wherever and having them procure the neccessary parts to validate what you think you know based on what you have seen.

If you see no difference, you conceed and pay for the labor and parts to get back to running condition.

I see that as SOOO much easier than trying to validate specs on a 35 year old car, no?

Rotories, easy to cheat - easy to catch - if you know what you are looking for like Chris said. Piston engines, just as easy to cheat - crazy hard to validate specs on out of production components and limited documentation.

[GKR_17]

Don't forget the oil system...

I've not built a wankel, but did stumble on to the info that the ceramic seals likely need higher than stock oil pressures to work right.

[lateapex911]

But seals are free right?

[Andy Bettencourt]

Don't forget the oil system...

I've not built a wankel, but did stumble on to the info that the ceramic seals likely need higher than stock oil pressures to work right.

Oil pumps (pickups) and rotor seals are free.

[seckerich]

The rotary is no different than any motor on port work, however we can not touch anything where everyone else gets to port match. . They have to match the stock part --period. The Turbo housing has a different casting ID and is easy to spot without teardown. If you do not agree with the outcome of the protest at the track you can appeal the decision and have the parts held as evidence for the appeal and shipped to an expert. Not the big hole you make it out to be. And for the record I had new, sealed parts shipped from Mazda per the request of my chief of tech at CMP because he was told to expect a teardown of a second gen RX7. If you plan to protest a car call the chief of tech for the race and give them a chance to prepare to tear down the car properly. All us rotary guys are cheating bastards, just ask Grafton.:rolleyes: He has the plugs to prove it. Have you had RX8 plugs made yet?

[Ron Earp]

Hey Chris,

Thanks for the pictures and post on the rotary and the offer on the housings. I've never disassembled one of the engines but have always been intrigued by them.


Fortunately cheating isn't rampant in IT.

The good thing is I feel that the sentence I wrote is true, at least in the areas where I race. Due to the efforts of folks like Steve E in the SE the rotary engines are policed pretty well and I do not think there are wide spread problems. However, not all regions are fortunate enough to have someone like Mr. Eckerich



You have uber-light forged pistons in your Z. I write a good protest asking for displacement, compression, cams and piston compliance - all checked.

Please tell me how much easier it will be to validate all that on your car (or Jeff's).


Andy, if we were to use my car for an example of the 35 year old car, you find that you'll will have absolutely no trouble validating specs for the cam (lift 7mm IN, 7.35 EX, etc.), compression (9.30 max), displacement (3.310" x 3.110", 2630cc max), and valve size (1.65" IN, 1.38" EX). In the shop manual those specifications are written in black and white and, for the convenience of US customers the specs are in millimeters and inches. With the exception of cam duration all the specifications can be fairly easily measured with tools most of us have at the track. Jeff's car is the same and even a little bit easier.

I think using these specifications is more straightforward than pulling a motor apart and judging if something is "stock as cast" or "not stock as cast". And then if the tech fellow (who we hope is a trained eye with rotaries cause if he isn't then it won't be easy for him to determine what is what) decides it is "non-compliant" we need to send it off to someone else (maybe, in your example we do so I'm sticking with that), a rotary engine expert, for a second opinion. With my engine, and others like it, if I'm running a 2.8L 280z motor I'll be found non-compliant at track, easy. Huge cam? Non-compliant at track. 10.8:1 compression? Non-compliant at track. The difference is with my engine an average fellow even casually interested in engines can check some critical parameters with simple hand tools - no previous experience needed. I show up in a Jensen Healey and the tech guy, having never seen one of the evil spawn of the devil engines before, can check the aforementioned items.

My initial reason for starting this thread wasn't to point out a specific protest action or find fault with any person or group. I simply wanted to try and get a consensus regarding getting even some basic rotary specifications in the GCR for future reference. The scientist in me likes numbers and things I can measure. However, it appears to me more folks are interested in explaining why we can't do that, or should do that, than suggesting ways we can do it, even if it is a simplistic first effort. I understand that it is a complicated problem. But, with the sort of talent we have amongst us almost surely solvable if it is something that the group feels is a real issue, which I gather most do not. And I'm okay with that as you folks have been at this far longer than I have.

[Andy Bettencourt]

I know your goals Ron. My point is that it's just as hard to prove your pistons weigh the right amount as it is to prove castings on a rotory. Both involve significant invasion, bith have no spec, both require a stock part to compare to.

You can buy new rotor housings from Mazda. Can you buy new OEM pistons from Nissan?

My overall point is that paper tigers exsist for all cars unless you go all the way.

[Ron Earp]

I know your goals Ron. My point is that it's just as hard to prove your pistons weigh the right amount as it is to prove castings on a rotory. Both involve significant invasion, bith have no spec, both require a stock part to compare to.

However, one modification has extremely minor performance ramifications while the other is quite considerable. Having pistons that weigh 65g less than stock probably won't show up on the dyno and offers a minimal performance advantage on track. Having a port that is slightly enlarged will show up on track and the dyno. The major aspects of a piston engine that enhance performance are easily determined by just about anyone.

I'm certainly not going to take the position that some do explaining that if it is too easy to cheat with a car then we either can't have it racing or have to place additional rules and regulations on the car. That disingenuous argument was used by some against having V8 cars in IT classes. It appears to me there is enough regulation on the rotary engines based on the fact that ports must be used as cast and no porting of any type is allowed. I just don't think that "no porting of any type" is going to be that easy to determine at the track and is relatively ambiguous for the untrained volunteer.

I do understand that the rotary engine ports are complicated. However, I do feel even having a rudimentary outside surface dimension with locations in the ITCS in the form of an engineering drawing would be helpful for racers and tech volunteers. I think it'd be an improvement, however minor.



You can buy new rotor housings from Mazda. Can you buy new OEM pistons from Nissan?

My overall point is that paper tigers exsist for all cars unless you go all the way.

Yes, new pistons are available straight from Nissan. Our man Riley at Lynchburg Nissan has been watching out for us and stockpiled lots of Z pistons. I use them and I think most L series racers do because they are high quality. Aftermarket pistons are available which are identical and are probably made by the same factory sans logo. However, for the extra ~$4 each I use the factory pieces.

[Andy Bettencourt]

I have always felt that we should build a template that slides on the header studs that shows the profile of the exhaust ports. Can detect everything but is a nice initial peak.

Also, knowing what RX-8 rotors look like vs. RX-7 ones is a good idea too. RX-8 versions have higher compression.

[JeffYoung]

This has been a helpful discussion. I do agree with Andy et. al. that there are some areas on a piston engine car that are hard to establish compliance for.

Ron's basic point to me does seem valid though. Port size is a basic power definig characteristic of a a rotary motor. I don't see any harm (and if you rotary guys disagree, let me know, I'm certainly no expert) in getting basic specs for the port sizes in the ITCS.

Greg, Steve, Andy, Jake have convinced me that certainly is not the end all be all, and may not matter much, but it is a start.

[Andy Bettencourt]

Port size AND SHAPE are the basic power defining characteristic of a a rotary motor.

Fixed.

[Greg Amy]

Fixed.
Agreed. If you can get a basic port shape, located relative to the exhaust studs as Andy suggested*, then I think that would be a good basic go/no go gauge that Tech can keep around for a quick check (remove exhaust manifold, stick in port, go/no go). Something like that would be relatively easy to fabricate.

GA

* If someone were really industrious and wanted to change the "cam timing" of the engine, they could also relocate the exhaust studs (though they could do the same thing inside as well). However, if someone is willing to go to that extent to cheat, well, then that's kinda like the Smokey Yunick 7/8 car and I think they deserve the "pass"... ;)

[JeffYoung]

Agreed x2. We are getting some stock housings from Chrs L. We'll measure and make some plugs, and locate them using the studs to (try, anyway) avoid the problem Greg mentions.

This may go nowhere but it is worth a shot in my view.

Steve E. -- any thoughts on this? You have been an invaluable resource here on how these motors should be built legally. Much appreciated.

[lateapex911]

So, this is for the exhaust?? Didn't Steve say the intake was where the performance payoff is? Or I think that was Chris. Either way, that's where I've always understood the real power gains to be.

Since Steve got (and wisely shipped them to the Steward) the plates, why not make templates of those openings? Reference your templates to the water jacket openings. (Make sure a Steward is present as a witness through the process to insure the conflict of interest issues can not arise. See also: OJ Simpson trial)

Once you have those, you can structure your protest in a staged manner, and using the template would net the obvious easy to spot changed opening cheats, saving the more thorough and expensive steps.

Bottom line to me though is, you guys want to nail the easy power cheats. Those are in the intake ports. Any real protest would involve a teardown to get and prove wrong doing, even with the template.*

* I think the visual intake manifold off inspections CAN yield obvious signs of tampering, and if it aint stock, it aint legal, so there is that as a first step, but it's not a 100% conclusive step.

[Ron Earp]

why not make templates of those openings? Reference your templates to the water jacket openings. (Make sure a Steward is present as a witness through the process to insure the conflict of interest issues can not arise. See also: OJ Simpson trial)

We should obtain said drawings via Mazda and avoid the "chain of custody" issue. Anyone have a contact at Mazda we could start with?

R

[seckerich]

Let me be real clear going forward. You will not tell if a rotary is cheated up unless you take it apart. Unless they are a total moron and grind the ports all the way. I hear these thoughts that a little bit goes a long way, it does not. It takes some serious porting to get where we do on the EP motors. All housings from mazda for the entire time the 86-91 6 port motors in ITS were made they were CNC cut on the intake openings. They are the same and are easily seen with something as simple as a paper tracing of a stock port laid on top. All the plugs in the world will not help because there in no access from the outside and the only port you could check has an inconel insert that blocks most of the opening. Nothing you put on exhaust studs will tell you anything. Do your homework before you post misleading statements.

If you want a true template then you need a cnc cut overlay of the side housings that locates on the 2 factory dowels and it will bust anyone that is changing or moving the port. I put stock housings on my CMM and reverse digitized them to get the basis for my ported EP stuff. A simple template .050 thick would do for any tech crew and cost about $50. I have checked more than I care to admit looking for the best and they are almost identical on the surface. Core shift in casting makes some flow better but that is the same with any cast piece. AKA flowing 20 SM heads to get the best. Mazda will not release prints.

You are getting a little carried away because of BS statements by those with the least knowledge about rotarys.

[Andy Bettencourt]

Steve,

They are asking for dimensions. Templates won't tell them any hp increases but at least it's a good step 1 in a protest to see if anything externally has been monkied with.

Just like a piston motor, like I said a ton of posts ago, you are going to have to take them both apart and go the extra mile.

If you think there is an issue, have your stock rotor housings ready and in the wrapper. Heck, pay for them and have them shipped to your chielf of tech for him to 'stock'. :)

[GKR_17]

Is it safe to assume that material usually isn't added when port work is done? If so, would it be possible to spec a volume, and use a similar process as would be used when checking compression? Or is there too much variation to be useful?

[Andy Bettencourt]

Porting for performance like Steve said is done internally to the intake ports.

I still get weirded out when I see missing fins in the exhaust ports.

[seckerich]

You don't get it andy. Anything short of a cad drawing will not even get you close to port shape. Have you ever even looked at one of Nicks motors? The only part of a rotay motor that gets machined at the factory is the first .050 in the cast iron face inside the motor. That is nothing you or anyone else have the tools or expertise to check at the track. A flat template is a perfect tool. Matches perfect, it is legal.

Grafton the only way to add material is with JB weld or similar. Housings are cast iron and then gas nitrided for wear from the factory. It is removal of material that cheats them up. Look at it as adding 20 degrees duration to a cam if you move the wall of the port. It leaves the intake open longer and has a little more volume. The runners are cast and vary so no port volume will tell you anything. Besides, flow is not always better on the bigger ports. It is really not this hard guys.

[MMiskoe]

At the risk of a thread derailment, I am curious to hear the opinion of the rotory guys who are here & appear to be pretty smart on it all.

Long ago I was told by a guy who'd built a few Wankels that if a 13B motor won't idle at 1000rpm w/o loping, its had some port work done. Is there any truth to this?

Although it hasn't happened in a while, there used to be a time when there was at least 1 RX7 on the ITS grid that either idled at 2500rpm or sounded as smooth as a Harley Davidson.

Matt

[Andy Bettencourt]

A flat template is a perfect tool. Matches perfect, it is legal.



This is what I have been suggesting the whole thread Steve.

Matt,

Massaging the ports is like changing the cams on a piston motor if you had to make a comparision, so yes, a loping idle is usually indicitive of some porting.

[lateapex911]

Not always.

My loping 12A has been thought to be ported, but the guy who did the carb insists that the carb setup he recommends is fastest, and it results in a loping idle. I can change carbs in 5 minutes, and have done so for doubters. With the race carb, it idles and runs like crap down low. Then I put the stock carb on and it idles great, purrs, but has no power. (Working on a best of both worlds combo).

My understanding of the 13B isn't as deep as my 12A knowledge, and that's not all that great as is, so I'll leave it at that.

[xr4racer]

You guys are thinking that this is going to happen and be done right are dreaming. The tech shed at the runoffs last year could not even measure a cam and valve lift in a Ford V8 AS engine. SCCA started a whole committee to investigate why everything was so messed up and this was in our premier national championship event. I for one hope all of the cheaters are ran off, but I doubt it will happen.

matt

[lateapex911]

Matt, as guy who's been on the wrong side of a screwed up protest for reasons similar to that, I hear you.
BUT, Ron and Jeff and Steve P are trying to work within the system to make it better. If the system isn't used, it will rust, and never work. But by USING the system, kinks and bugs get fixed. While I might be coming off as a detractor in this thread, (I hope not, but...) I'd prefer to think of myself as a devils advocate, ...but no matter what, I applaud the efforts, want to see them continue, and hope that success comes their way.

[Andy Bettencourt]

I think the main goal here is simple:

Give some guys who race against these cars some templates and basic dimesions and illustrations so that IF they protest, they have something to reference upon initial teardown.

To me, you then decide if you want to have the pieces shipped off to Topeka for the official decision based on what you see inside.

Jake: Hence the words 'usually indicitive'.

[JeffYoung]

That actually sums it up nicely Andy.

[Ron Earp]

That actually sums it up nicely Andy.

I agree.

And, I apologize if anyone on the thread has felt that I've posted misinformation about the topic. I don't know these engines well but thought the situation was important enough to start a discussion over.

Incidentally, I've always been interested in the wankel engines. My father used to write for model airplane magazines in the mid-70s when I was around nine or ten years old. Companies would send him products to test and I remember him getting model airplane engines to test out, a wankel engine and a radial engine. Both were obscenely expensive and produced by a German company (I think, don't know the name). Anyhow, he had a test bed airplane he used for this sort of thing and tried them both out. The wankel was just about impossible to get started and always was trouble but made a hell of a noise when running. Once I learned the engines were also in cars I always wanted a RX7 but never did manage to own one.

[lateapex911]

The wankel was just about impossible to get started and always was trouble but made a hell of a noise when running.
Sounds about right, LOL. They DO like things a certain way!


Once I learned the engines were also in cars I always wanted a RX7 but never did manage to own one.
No, you didn't, you think they're shitboxes! ;)

[Ron Earp]

No, you didn't, you think they're shitboxes! ;)


No no no. RX7s are race cars. Front engine, rear wheel drive. The natural way of things.

Now, if it was a FWD car, particularly of the hatchback variety, four door or two door, then yes it is a shitbox. And of course I'm not 100% serious. A bit serious, but but 100%

[lateapex911]

I hear ya, LOL. You're only 99.8% serious. ;)

Didn't Mustangs come with hatchbacks and 4 cyl engines for a while? Was it the sophisticated suspension that kept them from being shitboxes? ;)

[Ron Earp]

Didn't Mustangs come with hatchbacks and 4 cyl engines for a while? Was it the sophisticated suspension that kept them from being shitboxes? ;)

Nah, RWD keeps them out of the sheetbox category. As for those four banger pinto motored stangs, I had one that made a bit over 300hp, at the wheels. In the 90s that was some pretty serious street fun, although nowadays not so much.

[JeffYoung]

The defining line between shitbox and piece of shit is definitely FWD/RWD.

Ratty ass old GTi? Shitbox.

Ratty ass old straight six Camaro? POS.

I'll lick a lollipop to that!

[C. Ludwig]

Long ago I was told by a guy who'd built a few Wankels that if a 13B motor won't idle at 1000rpm w/o loping, its had some port work done. Is there any truth to this?

Matt


This is just not true. We build and tune mostly fast street cars which are mostly all "street" ported. With good tuning you can get a pretty aggressive street port to idle smoothly at 800 rpm. Now that programmable fuel injection is legal it would be easy for someone that knows what they're doing to pass off a street port in terms of idle characteristics.

If idle characteristics are the factor used to judge, more people will be indicted on the basis of poor tuning skills that actually cheating.

There is porting that will cause a loping idle, but I can't believe anyone would think they'd ever slide such an engine passed anyone in terms of tech.

[ddewhurst]

I have read only patrs of this thread. With the subject at hand, has anyone talked to Topeka/Jesse Prather/Dave Lemon. It is my understanding that Jesse & Dave had gone through this whole deal & forwarded a plan to Topeka several years ago.:o

[seckerich]

I have read only patrs of this thread. With the subject at hand, has anyone talked to Topeka/Jesse Prather/Dave Lemon. It is my understanding that Jesse & Dave had gone through this whole deal & forwarded a plan to Topeka several years ago.:o

That was for the definition of "street porting" in EP and they have pictures and guidelines on the Mazdatrix site as well as SCCA links. Stock is stock, no need to define it.

[C. Ludwig]

Here's a thread on rx7club with good pictures that may help explain this mess to those that have never seen the inner workings of a rotary. Believe it shows pretty well how easy it would be to spot intake port work with the naked eye, let alone a borescope. And why it would be all but impossible to spot exhaust port work with a lollipop or an external template.

http://www.rx7club.com/showthread.php?t=908708

In this pic two stock ports are compared to the street ported iron. The port work is fairly extensive and would be very easy to spot with the intake manifold off. What you need to look at on the stock irons is the lip that is CNC milled into each port (red arrows). The contrast between that milled portion and the cast portion is impossible to recreate by hand. Modification of that contrast, and the resulting tooled surface of what should be a cast intake runner is a dead give away of intake porting. Again, even if it's mild work, it's painfully easy to spot without the need for measuring devices or engine dis-assembly.


http://www.lms-efi.com/stuff/DSC00150.jpg



This picture in particular

[seckerich]

Thanks Chris, saved me uploading pictures I took this week.:023: