How dyno numbers are utilized by ITAC

[gran racing]

When dyno results are supplied to the ITAC for review, how is that information interpreted? What I mean by this is the process generates the crank HP rating versus what most of us would provide, the wheel HP rating.

Does the ITAC have assigned drive train losses for various cars for this purpose? If so, what are they?

Does the different type of dyno being utilized impact the calculation to what the crank HP rating equals (using the supplied wheel rating)?

What, if any, other factors are used in making the wheel to crank HP calculation?

[Andy Bettencourt]

During my tenure, we used 15% loss for mid-engine and FWD and 18% for RWD.

For me, DynoJet info needs a ton of 'backup', meaning lots of data from lots of sources. The nature of the system doesn't lend itself well to tight repeatability. The next most common is the DynaPack and is very close unit to unit but still can be manipulated with manual inputs. Common misconception, or old school thought, is that they read low compared to Jets. Back to back testing has debunked that for us.

[JLawton]

Having seen for myself how easy it is to manipulate the numbers.................... I'm not so sure how much stock we should put in these numbers.

(when I say "manipulate", i don't mean it like someone is purposely trying to pull a fast one. It's just that there are many variables that can be easily changed.............)




.

[JeffYoung]

THis is the area where the Process is not so subjective, which concerned all of us (I think that is fair to say). Kirk came up with a solution, which is called the "confidence factor" vote where we all act as checks and balances on the others in assessing dyno and other power information.

But in short, while the procedure is faily loose, we:

1. Look at and assess the dyno sheet, who it came from, type of dyno used (ALL are manipuable and Jeff is 100% right you have to be wary of all of them), etc. to determine how much trust/faith we put in the number. Obviously, the more sheets we have the better.

2. Then we use the 15/18% drivetrain loss numbers Andy mentions (debate over those as well) to figure out how much gain over stock we are seeing.

And then we have a big pow-wow where we bang on drums, commune with the Great Spirit and pull a number our of our ass! Seriously, we do have a pow-wow where we each state our confidence level in the numbers and then vote on what we think is the right gain modifier.

The worst thing about the system (but necessary) is using dyno numbers that can be gamed. The best thing is that we as a group all work as checks and balances on the others to avoid a bad result.

So far it has worked.

[ajmr2]

Hey Jeff.

You posted the specific document in a previous post. It might be helpful to post it on this subject in the title.
AJ

[JeffYoung]

Posted again.

Can one of the moderators put this in a sticky entitled ITAC Ops Manual?

Thanks.

Jeff

[gran racing]

Good idea and all set now.

[JoshS]

Good idea and all set now.

Probably better to post a link to the SCCA site instead of an attachment, so that if it changes, the latest one will be there.

[gran racing]

The SCCA site is changing on 8/14 (I believe). Do you know if it'll use the same URL? One would think so but...

[Knestis]

Probably better to post a link to the SCCA site instead of an attachment, so that if it changes, the latest one will be there.

Probably better to DO BOTH, so that WHEN changes, there will be a some documentation of the history of how we got where we are.

K

[gran racing]

LMAO!!! Sorry, something just came to mind. :D

[bamfp]

During my tenure, we used 15% loss for mid-engine and FWD and 18% for RWD.

For me, DynoJet info needs a ton of 'backup', meaning lots of data from lots of sources. The nature of the system doesn't lend itself well to tight repeatability. The next most common is the DynaPack and is very close unit to unit but still can be manipulated with manual inputs. Common misconception, or old school thought, is that they read low compared to Jets. Back to back testing has debunked that for us.

I have had two cars that were first dynoed on a DynoPac and then on the DynoJet at work. Both cars made the exact same whp on both dyno's.

[lateapex911]

I have had two cars that were first dynoed on a DynoPac and then on the DynoJet at work. Both cars made the exact same whp on both dyno's.


yea, well, YOU know what you're doing, lol.

Blake I bet Andy was thinking about hoe Jets are found on every street corner in all sorts of condition....they can be very accurate, but as you know, half the battle is the operator.

When I was on the ITAC my degree of confidence was increased if the data being considered came from Blake....

[bamfp]

I did send you guys my 914's engine dyno charts and chassis dyno charts. I only wish something had come from that info.:(

[Andy Bettencourt]

I have had two cars that were first dynoed on a DynoPac and then on the DynoJet at work. Both cars made the exact same whp on both dyno's.

And this backs up what I said. When you go Jet to Jet the customer needs to notice things like tire positioning on the rollers, strap tension, etc in order to get the kind of consistancy I think people expect.

[JeffYoung]

I've read two articles -- one sent by Bob Dowie and the other by JimmyC on the Brown Board -- that show how easy it is to manipulate dyno data with correction factors, etc. I too at one point believed Dynapacs always read less than Jets, and Mustangs too. I now know that is completely false and totally up to the operator.

I think, honestly, this is one of the reasons I (and perhaps others) have in my mind "strengthened" the 25% default. Unless you, like with Blake, you know the dyno, the operator and the conditions, you are setting yourself up to be gamed.

All of this just reinforces what I remember being told from the start: dynos are great tools for comparative TUNING on the same dyno. Beyond that, comparing dyno to dyno is fraught with danger.

This remains the "dangerous" part of the process. If we move from 25% to 30% on a 100 hp ITC car that's almost 100 lbs. And it would be based on dyno data showing differences of 5 hp, which is getting past the resolution capability of even reliable dynos.

[bamfp]

I dynoed my car with street tires and the Hoosiers back to back on the DynoJet. It made a 5 whp difference between the two. The race tires making less. The amount of toe you run can also effect the dyno results.

[lateapex911]

Were the tire sizes the same??

[bamfp]

Very close. The street tires were taller and were on heavy steel wheels and they still made more HP.

[quadzjr]

I believe that is a reflection of the drag of a sticky tire v.s. a street tire. I have seen the same things on drag cars and the "1000hp supras".

[Bob Roth]

I believe the thing the ITAC criteria misses is considering the original hp per liter. Sure a 105 hp 9 to 1, 16 valve honda CRX that was limited to 6500 rpm might be bumped up to 130 hp with at 7500 rpm and headers and tuning. So big deal, its now .85 hp per liter.

The problem with the rules is how they treat an engine that is already 8200 hp readline and 1 hp per liter such as the the 99 civic si, del sol VTEC, S2000 or teg type R. How do these engines get to 1.25 hp per liter? Do you expect them to rev to 10,200?

My point is the ITAC assumes all engines can get to about.,9 hp per liter under the rules, the problem is cars shipped with engines at 1 hp per liter such as Honda S2000, VTEC or Type R are really badly classified. As the rules sit today, these cars have little development potential.and in fact are classed about a class above their potential when considered on a hp basis.

[JoshS]

The problem with the rules is how they treat an engine that is already 8200 hp readline and 1 hp per liter such as the the 99 civic si, del sol VTEC, S2000 or teg type R. How do these engines get to 1.25 hp per liter? Do you expect them to rev to 10,200?

This is why it is a process, not a formula. Those cars are not expected to get a 25% gain, or in some cases they get a weight break based on torque or displacement, or sometimes both.

[JeffYoung]

There is some truth to this but it doesn't hold water in all cases.

Case in point: Integra GSR. 1.8 liters and 170 hp stock. 185 whp or so in IT trim. Doing just fine.

Josh's point holds. If you can show that your motor does not make the expected gain, an adjustment will be considered.



I believe the thing the ITAC criteria misses is considering the original hp per liter. Sure a 105 hp 9 to 1, 16 valve honda CRX that was limited to 6500 rpm might be bumped up to 130 hp with at 7500 rpm and headers and tuning. So big deal, its now .85 hp per liter.

The problem with the rules is how they treat an engine that is already 8200 hp readline and 1 hp per liter such as the the 99 civic si, del sol VTEC, S2000 or teg type R. How do these engines get to 1.25 hp per liter? Do you expect them to rev to 10,200?

My point is the ITAC assumes all engines can get to about.,9 hp per liter under the rules, the problem is cars shipped with engines at 1 hp per liter such as Honda S2000, VTEC or Type R are really badly classified. As the rules sit today, these cars have little development potential.and in fact are classed about a class above their potential when considered on a hp basis.

[gran racing]

So without several dyno sheets being submitted with full builds, is there much value in one dyno plot? Seems like there needs to be a lot of trust and respect on both ends.

[Andy Bettencourt]

There is some truth to this but it doesn't hold water in all cases.

Case in point: Integra GSR. 1.8 liters and 170 hp stock. 185 whp or so in IT trim. Doing just fine.

Josh's point holds. If you can show that your motor does not make the expected gain, an adjustment will be considered.

Do you think a letter would get consideration for STOCK hp/liter? This car has a 1.6 and makes 160hp. Very similar to the S2000 and Type R, both that were seemingly accurately classes below 25%.

[JeffYoung]

Nope (at least for me) because we don't know what the gain might be. It could be a high revving low displacement motor that responds well to IT mods (the GSR motor) or one that does not (apparently the S2000 motor).

There does not seem to be a hard and fast rule in practice as Mr. Roth would suggest.


Do you think a letter would get consideration for STOCK hp/liter? This car has a 1.6 and makes 160hp. Very similar to the S2000 and Type R, both that were seemingly accurately classes below 25%.

[Chip42]

stock volumetric efficiency is not always a good indicator of IT Ve. it's a good gut check but not a good predictor using "expected" numbers. it's all about the efficiency of the system, and the resultant output will be driven by the weakest link. how IT allowances change this system tends to drive the gain over stock - if you replace a poor manifold wiht a good one, you will see more gains than replacing a good manifold with a very good one. if the head is crap, no amount of exhaust work will get you to 90% volumetric efficiency.

it's about as useful as expected gains, though, as they really are basically the same thing. the math on gains is easier to run and more digestable, so The Process, as is, is both just as good and easier to work with.

I can tell you from experience that a 20% gain on a B16 in ITS trim is not out of the question. 25% might be optimistic, but bolt ons will take it to ~15%+ assuming a 15% driveline loss.

as you noted, though Ve tends to be inversely proportional to displacement, or really a function of RPM. peak output of a well designed system will fall along a line for bhp/l vs RPM, but we can't use that as a universal predictor in IT.

my own car (AW11 MR2) breaks from the "norm" so I'm sensitive to the fact that all of these predictive mechanisms are general rules, NOT universal truths.

general gut check values I use:

a fixed cam car can often make as much as ~0.8-0.9 hp/L. age and displacement tend to drive the maximum for a given engine.

fixed profile, variable timing cams will typically inch this up by ~0.05-0.1

multi-profile cams or variable lift systems (VTEC, VVTLi) can often see 1.0-1.15+

[bamfp]

There is some truth to this but it doesn't hold water in all cases.

Case in point: Integra GSR. 1.8 liters and 170 hp stock. 185 whp or so in IT trim. Doing just fine.

Josh's point holds. If you can show that your motor does not make the expected gain, an adjustment will be considered.


I can tell you that we are making nowhere near 185 whp with Zsolt's GSR. We have not taken it to the "happy" dyno yet. But on my Dynojet at work and the Dynopac it is under 170whp. No BS.

[Greg Amy]

With 10.9:1 compression, better-than-stock cams (but not STL-optimized), titanium springs and retainers, and adjustable cam gears (otherwise, an ITS legal engine) we were making 186whp on a Dyno Dynamics (well, before the crappy cam gear broke, anyway).

And although we are currently about 150 pounds lighter than an ITS Acura Integra GSR, I've twice lost STL lap records (and two races) to ITS-legal Mazda RX-7s (Lime Rock and New Hampshire).

I'd careful out there on that Island Of Conclusions you're jumping to...

On edit: also forgot to mention that we removed the GS-R's intake manifold butterfly/plate (no clue if it makes a difference), disabled all the intake manifold/throttle body coolant hoses, and we're also running an aluminum flywheel. And, to the chassis performance, we're also running an ITS non-compliant close-ratio Integra Type R gearbox (OS Giken LSD). All this, and I'm still friggin fighting with ITS RX-7s...maybe I just suck...

[Jeremy Billiel]

Our ITS GSR just before it blew up (i.e making its peak power being loose) made 168 WHP on a dynopak.... A VERY long way from 185 WHP

In ITS you will NEVER, EVER get to 185 WHP

The notion that GSR's take well to mods is laughable... 15-20% gains is all you will get.

[gran racing]

18 HP difference between the two dynos? Or were there other differences from one reading to the next?

[Jeremy Billiel]

18 HP difference between the two dynos? Or were there other differences from one reading to the next?

Two different engines dave

ITS Trim: 168 WHP dynapak
STL Trim: 185WHP dyno dynamics

[Greg Amy]

I am referring to this year's STL engine with all those listed mods, the one I lost at Watkins Glen last weekend due to cam gear failure. That dyno tuning and testing was done at Xenocron (http://www.xenocron.com/)'s Dyno Dynamics dyno the Friday before the MARRS4 weekend.

Billiel is (awkwardly) referring to last year's ITS-legal engine, the one that we lost the oil pump on at the 2010 Runoffs. His dyno numbers are from Kessler's Dynapack.

[JeffYoung]

Zsolt told me higher numbers, but I don't want to get into an internet discussion about it.

I've been on track against that car and fast ITS legal RX7s and it's not hurting for power. I think its aero top end helps it, but it isn't loosing races to the Steve Eckerich and Kent Thompsons and Chuck Hines of the world due to power. Helll the vid of Zsolt rolling Chuck on the backstretch at RA was pretty damn impressive.

FWIW, my peak number is 181, but most pulls were high 170s, and I run at 2670, and Zsolt and my car are very close on the straight.



I can tell you that we are making nowhere near 185 whp with Zsolt's GSR. We have not taken it to the "happy" dyno yet. But on my Dynojet at work and the Dynopac it is under 170whp. No BS.

[JeffYoung]

Jeremy it's impossible for me to take that seriously when you didn't even try on the ITS motor.



Our ITS GSR just before it blew up (i.e making its peak power being loose) made 168 WHP on a dynopak.... A VERY long way from 185 WHP

In ITS you will NEVER, EVER get to 185 WHP

The notion that GSR's take well to mods is laughable... 15-20% gains is all you will get.

[Jeremy Billiel]

Jeremy it's impossible for me to take that seriously when you didn't even try on the ITS motor.

Thats fine. Use Blake/Zolts number. Same HP. Why? Because GSR's do NOT take to modifications easily.

Don't kill us just because Greg and I saw the writing on the wall and that the motor was not going to make that kind of power. Blake/Zsolt have done more development and spent more money and are still in the same range for hp.

[JeffYoung]

I'm not trying to kill anybody. I understand you guys made a call based on what you believed to be true about the ITS GSR.

I just don't think that conclusion is accurate. Scott Seck's car wins races against some of the best ITS RX7s at Daytona, a pure power track. Zsolt's car runs the straights just fine with my car, and other cars that I know make 170+ whp.

The GSR is not at a power deficiency in ITS.


Thats fine. Use Blake/Zolts number. Same HP. Why? Because GSR's do NOT take to modifications easily.

Don't kill us just because Greg and I saw the writing on the wall and that the motor was not going to make that kind of power. Blake/Zsolt have done more development and spent more money and are still in the same range for hp.

[Jeremy Billiel]

Jeff - This discussion had nothing to do with on track performance....

And I quote "Case in point: Integra GSR. 1.8 liters and 170 hp stock. 185 whp or so in IT trim. Doing just fine."

Your statement is just flat out WRONG. It may be ok on the track for other reasons (I don't buy it), but this conversation started because you are making blanket hp statements that are crazy. This exact statement is what makes all the IT membrship pissed off when dyno sheets and projected hp numbers come into play.

Show me a full out ITS GSR build that makes a 185 WHP. I know what Scott's makes and its not even close....

[Greg Amy]

Jeff, you have my encouragement to say "I told you so" when an Acura Integra GS-R is pulling 1:39s at Road Atlanta. Or, maybe when an Acura Integra GS-R is keeping up with the BMW E46s up here in the Northeast (the ones that are setting lap records and are usually winning overall in the ITS/ITR group.) I'll even personally buy - and bring to you - that six-pack of your favorite beverage to drink while watching me eat my hat.

Remember, there's a much bigger world out there than a few tracks in the Southeast...just sayin'...

GA

[JeffYoung]

Turn around is fair game -- there is a bigger world out there than LRP and Pocono and Watkins Glen. Those "few tracks in the Southeast" include places where some of the very best RX7s and Z cars run (we do not have the E46s you guys do in ITS).

I'm confident that the GSR is one of the cars to have in ITS, and I'm confident it can make north of 180 whp. I wouldn't "vote" that way on the ITCS without data to back it up, but from what I've seen that's my personal conclusion and I think it is based on better experience than Jeremy's honestly.

I've heard the GSR guys say they think it can run 1:40 at RA. There is only one car/driver combo that runs under that recently, and I think anyone who looks at that situation objectively will admit it's the driver and not the car responsible for it.

The GSR is not at a power deficit in ITS. In fact, whether it is aero or power, from what I've seen, there is not a faster car in ITS above 125 (although I've not seen the ITS E46s).

May not be at a 100% "I told you so" place right now, but we are rounding third and headed for home.


Jeff, you have my encouragement to say "I told you so" when an Acura Integra GS-R is pulling 1:39s at Road Atlanta. Or, maybe when an Acura Integra GS-R is keeping up with the BMW E46s up here in the Northeast (the ones that are setting lap records and are usually winning overall in the ITS/ITR group.) I'll even personally buy - and bring to you - that six-pack of your favorite beverage to drink while watching me eat my hat.

Remember, there's a much bigger world out there than a few tracks in the Southeast...just sayin'...

GA

[Chip42]

the GSR has a nice low-slope hp curve and a very flat torque curve. the P72 cams,head, and intake combo is designed for that. You'll see peaky power on the B16/17/18C5 due to the P30/whatever head, cams, and those intakes being better for building HP. the P72 intake, in particular, is restrictive to building peak hp.

I don't think 125% on a GSR is likely, but I think it makes up for that in large part due to the overall package and wide power curve, and really good driving.

[seckerich]

Irish Mike ran a 10/10ths E46 with us before going to ITR. It could be beat and Mike is a top notch driver so that is a fair data point.

[JeffYoung]

This is ITS Jeff speaking, not ITAC Jeff.

I don't buy it. Zsolt's car has more top end (both from personal experience and from watching his in-car data) than any other ITS car I've seen. Note I don't think the car is misclassed or anything, and I don't think it needs any adjustment.

But I think it makes really good power, and significantly more than 170. It's aero is good, maybe best in class, and that may explain the 125 mph+ advantage it has, but I'm personally convinced some of it is power.

I think all of the good S cars (other than the Miata, which is at a lower weight) are in the 170+ range.

I know that when I was making 160 whp or so, I couldn't compete. The jump to high 170s/181 was a big deal and changed the game. The three GSRs I've seen seem to be in "top ITS car" power ballpark.

Steve, forgot IMike ran that in S. Before the time where I was competitive, so I probably only saw him when lapping me.

Bottom line to me is there are a number of cars that can win in S (240z, 260z, 280z, 300zx, E46, E36, E30, Porsche 944S, TR8, Miata, RX7, Corrado). GSR is one of them.


the GSR has a nice low-slope hp curve and a very flat torque curve. the P72 cams,head, and intake combo is designed for that. You'll see peaky power on the B16/17/18C5 due to the P30/whatever head, cams, and those intakes being better for building HP. the P72 intake, in particular, is restrictive to building peak hp.

I don't think 125% on a GSR is likely, but I think it makes up for that in large part due to the overall package and wide power curve, and really good driving.

[Chip42]

Bottom line to me is there are a number of cars that can win in S (240z, 260z, 280z, 300zx, E46, E36, E30, Porsche 944S, TR8, Miata, RX7, Corrado). GSR is one of them.

on this, we agree.

[gran racing]

and that may explain the 125 mph+ advantage it has

What about 0 - 125 mph? Hey, maybe it's fine, don't know or really have an opinion either way. I do like the curve of the GSR dyno plot Greg posted (was jealous as mine is no where near as smooth) but that really doesn't matter as far as the process is concerned. Just peak, right?

[Z3_GoCar]

Since I'm leaving IT and the 2.8 behind, here's what I have for dyno plots, maybe it'll help put the car in ITS at its same weight....

The motor, it was professionally built in January 2001 for world challenge, stock aluminum block, head from a 1996 M3 3.0l S-50 including s-50 cams, M3 euro Supersprint long tube exhaust headers, S-50 OBDI intake manifold, titanium valve retainers, 11.5:1 CP pistons that are 0.003 oversize (that's an 84mm piston, not 84mm bore as came from the factory), Electromotive TECII ecu with 30lb/hr low-impeadance RC injectors, M3 lightweight oil pan and S-54 oil pump, M3 oil filter assembly with oil cooler fittings and S-54 oil cooler mounted under the oem radiator, since the ecu doesn't use a MAF it's been removed, and an aluminum single mass flywheel. The throttle body is stock, and had the original 325 flat-plat restrictor behind it. This is how it dyno'ed:
http://www.improvedtouring.com/forums/picture.php?albumid=20&pictureid=475

Now fast forward to making the motor as IT legal with everything that I knew about at the time. I removed the S-50 intake manifold, aftermarket fuel injectors, and aluminum flywheel, I added a MAF even though it's not connected to the ecu, purchased oe pink top 24lb/hr high impeadance bosch injectors, the correct OBDII intake manifold, and a dual mass flywheel. The result on the same dyno with the same tunner was:
http://www.improvedtouring.com/forums/picture.php?albumid=20&pictureid=476

So why won't it make power like the 2.5? The head's the same, intake cam phasing is the same, valve sizes are the same, cams are about the same, same piston bore, throttle body is the same. So what's different? The intake manifold is vastly different, smaller plennum, smaller runners that are round instead of oval shapped, smaller ports that can't be cut out to match the intake port vs intake ports that are manufactured to match the head ports, the rods are longer with a shorter pin height, so the compression ratio is 0.3 less (10.2:1 vs. 10.5:1). Simple answer, move the choke point into the intake manifold and no matter how you build it, it won't respond.

[JeffYoung]

Yes, just peak.

I think in ITS my car/Z cars/GSR/Miata/RX7s race really well. Zsolt's car has more mid than a good RX7, but I have a significant advantage over him in the early part of the rev range after a shift.

There is a 30 minute race vid, primarily between Zsolt and me, in the SEDiv forum here, where you can see this. Cars are very, very closely matched. I think Zsolt has a slight top end advantage but I'm stronger in the mid and up to 110-120 mph.

Good racing with that car (and driver! Zsolt is fun to race with).


What about 0 - 125 mph? Hey, maybe it's fine, don't know or really have an opinion either way. I do like the curve of the GSR dyno plot Greg posted (was jealous as mine is no where near as smooth) but that really doesn't matter as far as the process is concerned. Just peak, right?

[bamfp]

The average mph Zsolt does at Road A and VIR is 125-127. Gearing is what has helped his car down the straight.

[JeffYoung]

Have to check the T-mate but I think that is about the same for me on the backstretch at VIR. Zsolt could draft around me, and I could draft around him. He just seemed stronger at the back end of the straight, me at the front. No surprise there I guess.

I do have recent T-mate data for Roebling and it shows 128.

[Greg Amy]

Interesting to note that the Triumph TR-8 has become the performance benchmark against which everything else in Improved Touring S is to be compared. Good to know, though...

;)

[JeffYoung]

It is for ITS Jeff, because it is the seat I sit in.....:)

Seriously, I understand you guys bailing on the ITS car. Ron and I were talking about this the other day, but at some point you get "ruleset burnout" and you just can't deal with some of the stupid/silly stiff inherent in the ruleset (and in inherent in any rule set) any more.

Plus you guys did a great job with the ST stuff. It may be the future of the SCCA.

I just don't buy the "GSR can't make power/can't compete in ITS" stuff. Fully developed (and you guys have to admit you didn't go full bore on the ITS car), I think it is one of the cars to have in ITS.

[Ron Earp]

I just don't buy the "GSR can't make power/can't compete in ITS" stuff. Fully developed (and you guys have to admit you didn't go full bore on the ITS car), I think it is one of the cars to have in ITS.

The GSR is competitive in ITS. Only Zsolt knows what sort of power GSR makes and if he wants to disclose that figure it's up to him. I've raced with him plenty of times though and he either had at least the same power I had out of my Sam Neave engine, which was 170 to 176 rwhp depending on temps. I suspect he had a tiny bit more.

I know that at VIR Zsolt and I were extremely close and I was able to observe numerous instances of the two of us leaving Oak Tree and him just able to get an advantage in the last 150 yards or so of the back straight. Aero or a few horsepower more? I dunno. But for sure his car is heavier than mine was. I've seen it run against a number of well driven ITS car types and it seems to hold its own.

If someone feels that GSR is competitve at 181 hp but it isn't at 172 hp then I think they're looking for an excuse to not run the car. The GSR as an overall package is competitive in ITS and the driver will determine the rest.

[Andy Bettencourt]

The E46 323 is an interesting bird. I have NEVER seen a dyno sheet but when one rolls our ITR S2000 up the esses at the Glen at the same weight, you would easily extrapolate 200whp. That puts that car about 150lbs light compared to the targets. I have no reason to believe the cars I am using as examples are illegal.

[JoshS]

The E46 323 is an interesting bird. I have NEVER seen a dyno sheet but when one rolls our ITR S2000 up the esses at the Glen at the same weight, you would easily extrapolate 200whp. That puts that car about 150lbs light compared to the targets. I have no reason to believe the cars I am using as examples are illegal.

These are not IT builds, and they include the E46 variants of the 323i, 325i, 328i, and 330i (323i and 328i are "M52tu", 325i and 330i are "M54") in all sorts of levels of tune, but ... based on my own car, which is the same as the 328i, and these dyno plots, I don't believe a legal 323i could get to over 200whp.

http://www.e46fanatics.com/forum/showthread.php?t=768715

[Andy Bettencourt]

These are not IT builds, and they include the E46 variants of the 323i, 325i, 328i, and 330i (323i and 328i are "M52tu", 325i and 330i are "M54") in all sorts of levels of tune, but ... based on my own car, which is the same as the 328i, and these dyno plots, I don't believe a legal 323i could get to over 200whp.

http://www.e46fanatics.com/forum/showthread.php?t=768715

I hear, as with the WC cars and some of the higher-end IT builds, that once you grab ahold of the VANOS with your progammable ECU, the power really comes.

[bamfp]

Before I left Sunbelt, we built an E46 engine with I think Motec,. It made very close to what Chet's E36 made.

[JoshS]

Before I left Sunbelt, we built an E46 engine with I think Motec,. It made very close to what Chet's E36 made.

Which engine?

[bamfp]

Honestly I don't remember. I am pretty sure it had dual vanos.

[JoshS]

Honestly I don't remember. I am pretty sure it had dual vanos.

They all have dual vanos. The 3.0 would have no problem making more horsepower than any E36. The others would take some good tuning, and I have my doubts about the 323i engine.

[chuck baader]

If I remember correctly, the ITS E36 motor was a 2.5 single vanos on the intake cam. CB

[Andy Bettencourt]

If I remember correctly, the ITS E36 motor was a 2.5 single vanos on the intake cam. CB

I think the conversation is specfic to the E46 versions.

[JeffYoung]

Maybe Steve E. can weigh in on the Irish Mike ITS E46 car. I vaguely remember it, but I think he converted it to an ITR car after a year or two. I don't remember it (the ITS version) running away from the field at Roebling though.

[Chip42]

in 2008 the then ITS 323 was leading the SIC over MVS when he spun entering 4. MVS went on to win in his miata (Andrew C won ITA in another ISC miata). I think the following year Irish Mike went to ITR with that car.

it wasn't a slouch but I would have expected it to pull a miata harder in a strait line. no doubt Irish Mike had it tuned as close to perfect as he could, so it's safe to call it a 9/10ths car, minimum. I remember his justification (to me, when I asked) for going to ITR that the 323 was too slow. I'm sure the actual response was much more colorful.

[JeffYoung]

As you know, that's a Miata track. I've seen the ITS ISC Miatas lose exactly once there -- to John Williams' 240z. I thought John still had the ITS track record, but looks like Mike has it now (still all very close).

Hard to gauge that track by times though, it is so temp dependent.


in 2008 the then ITS 323 was leading the SIC over MVS when he spun entering 4. MVS went on to win in his miata (Andrew C won ITA in another ISC miata). I think the following year Irish Mike went to ITR with that car.

it wasn't a slouch but I would have expected it to pull a miata harder. no doubt Irish Mike had it tuned as close to perfect as he could, so it's safe to call it a 9/10ths car, minimum. I remember his justification (to me, when I asked) for going to ITR that the 323 was too slow. I'm sure the actual response was much more colorful.

[quadzjr]

I was at that race between Irish Mike, MVS, and the ITR red BMW Z. that was an intense race. I believe they were constantly in 19's (could be wrong, but I remember they were on pace with our FP times that was inthe 18's.) For what it is worth the faster setup of the MVS ITA Miata (better splitter and new motor, and pre-roll at driver school) With Andrew C driving was about 1-2 seconds a lap slower than the ITS cars mentinoed.

so mathmatically

ITS BMW > ITS Miata (at miata track) at sebring Irish mike won.
Both ITS > quick ITA miata with good driver
quick ITA miata > ITA miata at last race at RRR
ITA miata at last RRR race>ITS TR-8 :D

[JeffYoung]

John Carter drives that ITA ISC Miata very well. He's not lacking for power at all though. He could stay in my draft at Roebling. The one place on the track -- the front straight -- where I should be able to put some distance on him, I could not. The rest of it, that's Miata heaven. ITA Miatas have won the overall there several times. I was lucky to beat him once back in April and thought I had him on Sunday in July, but he made a great pass on me in 1.

I don't think an S car has officially been in the 19s at Roebling. Track record is 20.5 (Irish Mike) and I think Charbonneau and Williams have been in the 20s. Best I've done is a high 21.

[quadzjr]

John Carter drives that ITA ISC Miata very well. He's not lacking for power at all though. He could stay in my draft at Roebling. The one place on the track -- the front straight -- where I should be able to put some distance on him, I could not. The rest of it, that's Miata heaven. ITA Miatas have won the overall there several times. I was lucky to beat him once back in April and thought I had him on Sunday in July, but he made a great pass on me in 1.

I don't think an S car has officially been in the 19s at Roebling. Track record is 20.5 (Irish Mike) and I think Charbonneau and Williams have been in the 20s. Best I've done is a high 21.

Not saying that John doesn't drive the heck out of the car. That car has had some rough times. (it was rolled at the double school last year). It has a good motor, MVS puts out a good product. My point is that Mike in the BMW on a miata track was toe to toe with the best in ITS miata. Both with great drivers.

[JeffYoung]

John's car has a VERY good motor.

I am certainly not saying I'm among the best ITS cars to run at Roebling. I'm definitely one rung (at least) below Irish Mike, and Andrew, and Mike and Kip, and John Williams.

But I think I have enough time up front at the track, and in racing with the Miatas, to think that a well prepped, well driven ITS or ITA Miata is going to very, very hard to beat there. Can be done, certainly, but that track -- a big long momentum track - is perfect for that car.

The only place I have an advantage, or a Z car, is the last 1/3 of the front straight, and even there, Mike at ISC has done so well with power development that this disadvantage seems to have disappeared.

Just confirms that there is always development to be done.

[quadzjr]

John's car has a VERY good motor.


I know it has a good motor.. it is the same car/motor Andrew C. drove during the SIC race that was mentioned before. That he (Andrew) was running around significnatly faster per lap faster a few years agoan what John was doing at the last race at RRR acording to MVS while he was timing john during qualifying sessions. Although htis last weekend the track was fairly greasy IMHO.

Actually during the last race they did adjust the tune on the computer to help resolve some lean conditions they were having. Seemed to work as the plugs looked good when he came in during the middle of the saturday qualifying event.

[JeffYoung]

As you know, that track is very temp dependent.

In qual in the morning you basically got (in my car anyway) one or two laps before you couldn't get grip in 8/9, which as you also know kills your lap times.

FWIW, I think John's times in the 22 would be up there with Charbonneau's in the fall.

FWIW again, where John "beats" ITS cars is in two places. Turn 6 and 8/9. He's on the gas way earlier than us in 6, and then flat through 8/9.

I could pull him in 3, and some on the front straight if he was not right in my draft. 4/5 was a wash, as was 1/2.

[quadzjr]

Watching all of the miata that drive for MVS they have the mojo. They all seem to take the same lines and they are fast. I have seen the traqmate data for the cars and it is impressive. My favorite is the 5-6 area.. Flat... slight lift.. flat again.. I have tried to do that in my car.. not a chance.

but for the original question, Atleast one BMW in ITS was fast against a fast ITS miata at a miata track. Who knows what was done, to the car and what prep level? You can always ask Irish Mike, he is a pretty cool guy. Dan might know as well?

[gran racing]

When using drive train loss percentages to estimate flywheel HP from dyno numbers, does that percentage decrease the higher the cars HP is?

For example, we dynoed a 348 HP RWD car today. Should we use 18% to get close to the flywheel number? What if the car was only 150 HP (still RWD)?

[erlrich]

When using drive train loss percentages to estimate flywheel HP from dyno numbers, does that percentage decrease the higher the cars HP is?

For example, we dynoed a 348 HP RWD car today. Should we use 18% to get close to the flywheel number? What if the car was only 150 HP (still RWD)?

The more I think about it, the more I think that is a really good question. Why in fact do we use a % for drivetrain loss instead of a constant value? Does a 300 HP (crank) RWD car actually require 18 more HP to turn its drivetrain than a 200 HP RWD car?

[gpeluso]

I understand that a dyno produces only a number that can be manipulated....but wouldn't it be a great idea for a region sometimes to have a dyno available to put top runners on to see comparables of that time and day....still a number...but should be relative to each other. Now this should not be used to dq anyone but it sure would make people think that something is going on with THAT car or an adjustment is in order from the powers to be.....might help honesty? or just scare people into honesty. What I read about what Greg Amy did with that whistler was a neat idea that was not used to dq people at all.... just informational purposes and it sounded like it worked.

Greg

[JeffYoung]

This is a good question. I had this discussion with someone not long ago actually.

You would think the loss stays constant but at least two other factors to consider:

1. There is some legitimate literature out there suggesting it does not. As hp increases, you get more losses in the tranny, etc. I'll try to dig it up

2. Second, for IT purposes, remember we are dealing with "batches" of cars, grouped in 60-80 stock hp (ITC), 80 to 110 (ITB), 110 to 140 (ITA), 140 to 190 (ITS) and 190 to 240 (ITR). This reduces the effect of the use of a percentage since it's not like we are comparing an 80 stock hp car to a 240 one.

[DavidM]

How dyno numbers are used to back-calc crank HP is the biggest issue I have with the process. A small change in one number can mean plus or minus 100 lbs for a car. We all know what sorts of debates have been had over 100 lbs.

David

[JeffYoung]

Yes, and it gets worse in the lower classes where 1 hp can be 20 lbs.

[Andy Bettencourt]

How dyno numbers are used to back-calc crank HP is the biggest issue I have with the process. A small change in one number can mean plus or minus 100 lbs for a car. We all know what sorts of debates have been had over 100 lbs.

David
That's why the ITAC has it's 'confidence vote' and requires much more than one dyno sheet from one source.

And as long as the drivetrain loss is applied consistently, that piece isn't a variable.