The Use of SIRs in IT

[Ron Earp]

There is an interesting blurb on SIRs in the recent issue of Road and Track entitled “Formula For Power”. The short article discusses evening up the playing field for the Le Mans race. I quote:


To give cars of different engine capacities an approximate equal chance, the maximum power obtainable is limited by one (or equivalent two) air restrictors limiting the flow of the engine’s intake air.

When the speed of the airflow through the restrictor reaches the speed of sound, the flow cannot be increased, limiting the engine’s power. Roughly speaking, if the diameter of the restrictor is such that the airflow reaches the speed of sound for a 4 liter engine revving at 5000 RPM, it will also be reached by a 2 liter engine revving at 10000 RPM, both engines theoretically making the same power.

In practice, however, the car with the bigger engine will have an advantage because the air restrictor hardly affects the engine’s maximum torque, which is higher for the bigger engine. Consequently, to equalize the changes of cars using different size engines, smaller capacity engines are allowed a slightly larger restrictor than those of higher capacity, which compensates for their lower torque with slightly more power. In the case of turbocharged engines, smaller engines are allowed a higher boost.

This is in fact a sort of handicap formula, but is has been established by a component engineering formula and has worked quite well over several years. As an incentive to technical development, the formula is surely less interesting than, for example, a fuel consumption limitation. But when the maximum intake airflow speed has been reached, improvements in the combustion efficiency and reduction of friction losses can still yield more power.

So, to make these things work for IT, a lot of R&D will have to be done with engines of various sizes to make sure they are appropriate and account for torque of larger motors. Is the ITAC and CRB ready for this and willing to handle the process? There is still plenty of debate and changes in SIRs at the professional level. Is club racing ready for this? (probably no worse than the debates we're having, right?).

SIRs don't belong in IT. The recent discussion with the BMW and SIRs really does not sound like IT racing to me. IT was/is, I thought, about racing at a grassroots level and is an entry form of racing in the SCCA. Incorporating SIRs into a regional level racing program seems like overkill and does not offer any advantages to good old tried and true lead.

R

[dickita15]

SIRs don't belong in IT. The recent discussion with the BMW and SIRs really does not sound like IT racing to me. IT was/is, I thought, about racing at a grassroots level and is an entry form of racing in the SCCA. Incorporating SIRs into a regional level racing program seems like overkill and does not offer any advantages to good old tried and true lead.
R
[/b]

SIR's are intended to be a tool to allow the club to level the field and allow a wide group of cars to be classed and still have good racing. That sounds like IT to me.

I think logical positions could be:

SIRs or weight should be use to level the field.

SIRs should only be used when they become less leading edge technolegy, in the mean time we should just use weight.

no leveling of the playing field should be done. there is no guarantee of competivness.

I am leaning toward the second one.

[Joe Harlan]

SIRs don't belong in IT. The recent discussion with the BMW and SIRs really does not sound like IT racing to me. IT was/is, I thought, about racing at a grassroots level and is an entry form of racing in the SCCA. Incorporating SIRs into a regional level racing program seems like overkill and does not offer any advantages to good old tried and true lead.

R
[/b]

Ron, you should qualify the above statement as your opinion.

Advantages of SIR's:
1: reduced engine costs
2: closer racing
3: no increase in wear items over the length of a season
4 a more consistent manner in which to balance a class (lead has different effects on different cars)



The disadvantages of lead are:
1: increased tire wear
2: increased brake wear
3: increased engine wear
4: increased transmission wear
5: increased fender wear (car will not turn like they used to)

I would estimate that 300lbs over the length of a 10 race season will cost about 6000 dollars a year in extra’s and these are facts I can back up. I have practical experience with the cost of a 3300lb touring car. What this article fails to mention is the use of both SIR’s and Weight as a balancing tool. You first must get the cars in the same weight/power window with an SIR then balance the torque issues with weight. In the case of a BMW we have the torque issue pretty well understood so if we can limit the HP (topend) the class gets much closer to balance. Most of this is my opinion but most of it can be backed up with facts.

SIR’s once sorted will be a very good thing for club racing and I believe(opinion here) in the end that it will account for the return of actual racing in the sport.

[Ron Earp]

Ron, you should qualify the above statement as your opinion.

Advantages of SIR's:
1: reduced engine costs
2: closer racing
3: no increase in wear items over the length of a season
4: a more consistent manner in which to balance a class (lead has different effects on different cars)

[/b]

Naturally Joe, I would think that everyone reads the forum and is aware that people post their opinions. As you did. And as I am about to do.

Your "facts" 1-4 are not all proven to be true - yet.

1. reduced engine costs - how? Development will be more expensive with SIRs in place. Why? But when the maximum intake airflow speed has been reached, improvements in the combustion efficiency and reduction of friction losses can still yield more power. So, we change from getting maximum hp from the motor to optimizing everything under the effect of the SIR. Sounds like a lot of ECU time and dyno time, coatings, bearings, and other yet unknown tricks to get every last 1/4 hp out where as before one was satisfied to get every 1 to 2 hp out.

2. closer racing - Maybe, but the SIRs aren't as straightforward as they were thought to be. And, we'll need different SIRs tested on all manner of engines to level the field. Small motors will need slightly larger SIRs than calculated to make up for torque deficiencies, big motors will always be suspect on making too much torque, etc. Who is going to check all this? Who will make sure it is right? The ITAC is hard pressed to get weights right. There is no time, manpower, and money to handle all the testing that will need to be done.

3. ok

4. I'd say lead is consistent. It'll reel in the fast cars and can be adjusted cheaply and easily. Too much? Take off 100lbs. Too little? Add 100lbs. I guess count me in the class of disbelivers that don't buy that the addition of 300lbs of weight will take a uber competitive car, a winning car, down to a unracable box in one fell swoop. Yep, it'll increase wear a bit, but there are lots of cars that wear brakes, pads, and tires out extremely quickly and as far as I know the BMW was NOT given an exception by the ITAC or CRB from this possibility.

I don't think you are going to like the proposed ITU class. The cars are going to be too heavy to your liking, but, fortunately choice is free and you don't have to race in it. Just like you don't have to race a BMW if you feel it weighs too much, wears things out too quickly, and costs too much to campaign.

[Joe Harlan]

Naturally Joe, I would think that everyone reads the forum and is aware that people post their opinions. As you did. And as I am about to do.

Your "facts" 1-4 are not all proven to be true - yet.

1. reduced engine costs - how? Development will be more expensive with SIRs in place. Why? But when the maximum intake airflow speed has been reached, improvements in the combustion efficiency and reduction of friction losses can still yield more power. So, we change from getting maximum hp from the motor to optimizing everything under the effect of the SIR. Sounds like a lot of ECU time and dyno time, coatings, bearings, and other yet unknown tricks to get every last 1/4 hp out where as before one was satisfied to get every 1 to 2 hp out.

2. closer racing - Maybe, but the SIRs aren't as straightforward as they were thought to be. And, we'll need different SIRs tested on all manner of engines to level the field. Small motors will need slightly larger SIRs than calculated to make up for torque deficiencies, big motors will always be suspect on making too much torque, etc. Who is going to check all this? Who will make sure it is right? The ITAC is hard pressed to get weights right. There is no time, manpower, and money to handle all the testing that will need to be done.

3. ok

4. I'd say lead is consistent. It'll reel in the fast cars and can be adjusted cheaply and easily. Too much? Take off 100lbs. Too little? Add 100lbs. I guess count me in the class of disbelivers that don't buy that the addition of 300lbs of weight will take a uber competitive car, a winning car, down to a unracable box in one fell swoop. Yep, it'll increase wear a bit, but there are lots of cars that wear brakes, pads, and tires out extremely quickly and as far as I know the BMW was given an exception by the ITAC or CRB from this possibility.

I don't think you are going to like the proposed ITU class. The cars are going to be too heavy to your liking, but, fortunately choice is free and you don't have to race in it. Just like you don't have to race a BMW if you feel it weighs too much, wears things out too quickly, and costs too much to campaign.
[/b]

Ron, How can you say engine costs are not proven? When you lower the stress on the engine(reduced RPM) you lower the cost period.

2. As far as balance goes it will be no worse than the current system (which was none until recently) and I would venture to say since only a few cars will qualify for an SIR it will be fairly easy to deal with.

4. you keep saying this but you can't back it up. once weight is rolling it has little effect until you either want to slow it down or speed it up or change its direction.
While you may be willing to spend 6k a year more to race a bimmer I am not sure the bimmer guys are willing.

Lastly save the ITU argument for somebody else. With the current trend in reducing the number of classes I don't see National jumping all over that deal anytime soon.
As far as cars being to heaving for my liking you clearly don't listen....I am currently running 2 T2 350z's at 3300 lbs each. That is one set of brand new hoosiers ever weekend Brake pads every other weekend a 600 dollar set of front rotors every 4 weekends a 4000 dollar set of calipers once a year. I promise what will make ITU not work is the cost of running a program. Notice Touring is not a big regional class and that is because it costs a lot to run expensive heavy cars. (crap i got sucked into that one)

[Ron Earp]

Brake pads every other weekend a 600 dollar set of front rotors every 4 weekends a 4000 dollar set of calipers once a year. I promise what will make ITU not work is the cost of running a program. Notice Touring is not a big regional class and that is because it costs a lot to run expensive heavy cars. (crap i got sucked into that one)
[/b]

While I can agree with some of what you say, cost of running is NOT holding Touring down. What is holding it down is cost of cars. I, and a lot of other IT racers, don't have the cash to procure a new model 350Z (Z4, Evo, etc.) to turn into a race car. The upfront costs of the Toruing cars and the aging out of them is what raises the bar to entry into Touring. IT cars, even proposed ITU cars, are cheap and readily available.

[Bill Miller]

SIR's are intended to be a tool to allow the club to level the field and allow a wide group of cars to be classed and still have good racing. That sounds like IT to me.

I think logical positions could be:

SIRs or weight should be use to level the field.

SIRs should only be used when they become less leading edge technolegy, in the mean time we should just use weight.

no leveling of the playing field should be done. there is no guarantee of competivness.

I am leaning toward the second one.
[/b]

That would be great Dick, but we've already been told that SIRs won't be used as part of the classification model. In addition, we've had a couple of cars that were recently shot down, even though their performance was close to that of the E36 or the Supra.

[Joe Harlan]

While I can agree with some of what you say, cost of running is NOT holding Touring down. What is holding it down is cost of cars. I, and a lot of other IT racers, don't have the cash to procure a new model 350Z (Z4, Evo, etc.) to turn into a race car. The upfront costs of the Toruing cars and the aging out of them is what raises the bar to entry into Touring. IT cars, even proposed ITU cars, are cheap and readily available.
[/b]

Ron, come on. There are manufactures out there that will discount the product down a ton to help the racer get into these cars. Most of them do not bleed off to lower classes they end up with license plates and returned to the street where there is a better market that will pay for them. I can get you into a 350 for close to dealer cost and have you racing it for 15k more. Tire support and engine support at a national level are huge if you can wheel the thing. You aren't gonna see that at a regional level. The cost of running a car far out weighs the cost of buying every time. You can justify 30k over 4 years for purchase. Justify 30k for a tire bill over one year.....If you can I'll have you sell it to my wife.

Enough of this for me. IT should not become a poorman's class to run old clapped out touring cars anymore than it should be dominated by the latest greatest manufacture that can gain ground by purchasing somebody at national to misclassify with a huge advantage.

[Bill Miller]

Ron, you should qualify the above statement as your opinion.

Advantages of SIR's:
1: reduced engine costs
2: closer racing
3: no increase in wear items over the length of a season
4 a more consistent manner in which to balance a class (lead has different effects on different cars)
The disadvantages of lead are:
1: increased tire wear
2: increased brake wear
3: increased engine wear
4: increased transmission wear
5: increased fender wear (car will not turn like they used to)

I would estimate that 300lbs over the length of a 10 race season will cost about 6000 dollars a year in extra’s and these are facts I can back up. I have practical experience with the cost of a 3300lb touring car. What this article fails to mention is the use of both SIR’s and Weight as a balancing tool. You first must get the cars in the same weight/power window with an SIR then balance the torque issues with weight. In the case of a BMW we have the torque issue pretty well understood so if we can limit the HP (topend) the class gets much closer to balance. Most of this is my opinion but most of it can be backed up with facts.

SIR’s once sorted will be a very good thing for club racing and I believe(opinion here) in the end that it will account for the return of actual racing in the sport.
[/b]

Well Joe, using your numbers, that means it probably costs the guy w/ the Supra over $10k more a year to run, than the guy in the E36. Racing costs money, period. You have a finite pool of money? Fine, make your own choice, more races in a less expensive car, or fewer races in a more expensive car. If anything, if your cost estimates are even close to accurate, the E36 got an even bigger gimme than I thought. The CRB needs to do the right thing and dump the SIR and set the spec weight of the E36 at the process weight, like every other car in the ITCS. The days of preferential treatment for that car need to come to an end. NOW!

[Joe Harlan]

Well Joe, using your numbers, that means it probably costs the guy w/ the Supra over $10k more a year to run, than the guy in the E36. Racing costs money, period. You have a finite pool of money? Fine, make your own choice, more races in a less expensive car, or fewer races in a more expensive car. If anything, if your cost estimates are even close to accurate, the E36 got an even bigger gimme than I thought. The CRB needs to do the right thing and dump the SIR and set the spec weight of the E36 at the process weight, like every other car in the ITCS. The days of preferential treatment for that car need to come to an end. NOW!
[/b]

Bill, we almost agree, Give the Supra an SIR reduce the weight and we are there. then you have two cars getting special treatment. (which isnst true, they are getting current treatment) You may as well face it the SIR train is on the tracks man. Lets get behind it and make it fair as fast as possible.

Edit: Bill it was no gimme.The E36 restricted will have to run the tire of the month like the rest of us to be competitive. As it is now they can set track records on RA1's. I have actual accounting of what costs are on a 3300 lab car for a season. Wanna know how much money I spent working on headers for a 240z or exhaust systems? The SIR puts the Bimmers on the same ground not special ground.

[Bill Miller]

Well Joe, if you give the Supra an SIR, and drop the weight, how do you justify not classing cars that make 190 - 225 hp in ITS? If we've got a tool that is going to clip cars to a desired output range, it should be used to class new cars, and not just to make a couple of cars more affordable to run. Rather than expend energy on unproven technology (at least on cars making IT-level power), let's get behind a class above ITS (and I don't care what it's called, could be ITF* for all I care). You could probably populate it w/ 15-20 different cars over the course of a weekend. Move the E36, E46, and 3rd gen. Supra up, set them at some decent weights, and drop in a bunch of other goodies that people would want to run. For example (and I know we've done this before):


944 S2
3.0 911
Acura RSX-S
E30 M3
RX8 (yeah, I know it's too new)
E36 2.8
300ZX
(just about any T3 car that is 5 years old)

[Joe Harlan]

Well Joe, if you give the Supra an SIR, and drop the weight, how do you justify not classing cars that make 190 - 225 hp in ITS? If we've got a tool that is going to clip cars to a desired output range, it should be used to class new cars, and not just to make a couple of cars more affordable to run. Rather than expend energy on unproven technology (at least on cars making IT-level power), let's get behind a class above ITS (and I don't care what it's called, could be ITF* for all I care). You could probably populate it w/ 15-20 different cars over the course of a weekend. Move the E36, E46, and 3rd gen. Supra up, set them at some decent weights, and drop in a bunch of other goodies that people would want to run. For example (and I know we've done this before):
944 S2
3.0 911
Acura RSX-S
E30 M3
RX8 (yeah, I know it's too new)
E36 2.8
300ZX
(just about any T3 car that is 5 years old)
[/b]

Final words-----------More racing less classes. Cars making 190 to 225 HP can be put right into ITS with this technology, You guys are looking at what you want today not will be a long term fix for the future. Enjoy the conversation from here. I had it on good authority the SIR is here to stay and while you all are fighting against the tide I am learning everything I can about how it will improve my program should I build a car that could run one.

[lateapex911]

Since the ITU concept was raised, and since we're talking about SIRs and their use in containing high hp cars....and regardless of whether the implementation of an SIR could or could not be done properly, how many folks would chose to:

Run the E36 or similar car in ITS at say 2850 with an SIR sized to limit crank to 220 or so, on 7" rims

or

Run the E36 or similar car in ITU at say 2650 unrestricted on 8" rims???

(And if chossing ITU, would the tire replacement costs not be as great (tire set-wise) because the tires are more appropriate?)

Just a consideration............

[Ron Earp]

Cars making 190 to 225 HP can be put right into ITS with this technology, You guys are looking at what you want today not will be a long term fix for the future.
[/b]

Why? Why restrict cars that make good horsepower? Don't we race to go fast, compete, and have fun? ITS is tapped out with the E36 325. Using SIRs to force more cars in S is just clear justification for why we need a class above S.

Regardless, none of this discussion has come close to answering a question I posed in the beginning:

" And, we'll need different SIRs tested on all manner of engines to level the field. Small motors will need slightly larger SIRs than calculated to make up for torque deficiencies, big motors will always be suspect on making too much torque, etc. Who is going to check all this? Who will make sure it is right? The ITAC is hard pressed to get weights right. There is no time, manpower, and money to handle all the testing that will need to be done."

Who gets to do all the fun work, make sure it is consistent and right, make sure it works, and maintain it?

Weight needs none of this - old school, low tech, but works with predictable results and easily adjusted.

[Bill Miller]

Using SIRs to force more cars in S is just clear justification for why we need a class above S.
[/b]

There it is, plain and simple. But wait, those 190-225 won't get classified because they are outside the performance envelope of ITS, and they won't use SIRs as part of the classification process. Becomes a self-fulfilling prophecy

Joe,

Right now, today, SIR technology has no place in IT. Create ITR (or ITU or ITF or IT#$$*(&&)_#$*(_@!&( for all that matter). Set the #/hp ratio at something around 10.5, and go for it. BTW, that puts an E36 making 250 crank hp at 2625#. It also puts something that makes ~300 crank hp @ ~2850#. That should keep the tire and brake wear in a reasonable range. Give them up to 17x8 wheels and be done w/ it.

One more thing, put a 3000# limit on the class. If your car would weigh more than that, based on the process, pick another horse.

[Joe Harlan]

Using SIRs to force more cars in S is just clear justification for why we need a class above S.[/b]

Never mind you guys feel free to propose all you want....as stated several posts back new classes have a slim chance of getting any where at this point.

[Ron Earp]

Never mind you guys feel free to propose all you want....as stated several posts back new classes have a slim chance of getting any where at this point.
[/b]

Joe, since you are so well connected to the pulse of IT why not spare us all the trouble and give us the "Joe Harlan IT Report" and tell us how everything is going to pan out over the next five years?

It'll save us the trouble of discussing things on the board since you already know where things are headed, what classes people want to race, what cars people want to race, as well as what classes will be around to race them in, and how to regulate them. No sense in using time discussing things that are known to be a waste of time.

Bill, I hear you on the class creation but 3000 lb might be low for a lot of the cars that could fit in the class. Might need to be a tad higher to accomidate a few like the Supra naturally aspirated and the 300z is something of a porker too.

[Joe Harlan]

Joe, since you are so well connected to the pulse of IT why not spare us all the trouble and give us the "Joe Harlan IT Report" and tell us how everything is going to pan out over the next five years?

It'll save us the trouble of discussing things on the board since you already know where things are headed, what classes people want to race, what cars people want to race, as well as what classes will be around to race them in, and how to regulate them. No sense in using time discussing things that are known to be a waste of time.

Bill, I hear you on the class creation but 3000 lb might be low for a lot of the cars that could fit in the class. Might need to be a tad higher to accomidate a few like the Supra naturally aspirated and the 300z is something of a porker too.
[/b]

You know Ron, you are the one that asked for thoughts on SIR's you are also the one that is trying to use SIR technology to lauch a class that you think is needed. I offered my opinion on SIR's and I am not convinced that a class is needed above ITS at this time.
Racing is about competition not always about how fast you can go. I have driven cars that made real big HP were fun for track days and weren't worth a crap to race. The best race cars are the cars that have lots of competition and close racing. ITS can have that and SIR's can help to create that. Look around about every nationally recognised set of classes has been reduced to about four. That is way I am not convinced that a new IT class is on the horizion anytime soon. As I said you guys have fun with this SIR's look like they are here to stay and will be used club wide. I am sure weight will be continued to be used also were and when it's needed. And BTW the Z32 300z could be in ITS tomorrow with a restrictor and I will gladly build the car and do the research before it's even classed. (looking for a donor as we speak)

[Ron Earp]

You know Ron, you are the one that asked for thoughts on SIR's you are also the one that is trying to use SIR technology to lauch a class that you think is needed. I offered my opinion on SIR's and I am not convinced that a class is needed above ITS at this time.
[/b]

Joe, this statement is incorrect. I am not trying to use SIRs to launch ITU. ITU is needed for the long term health of IT, in my opinon, and was on the table before SIRs came up. I used it to support an ITU in the context of discussing SIRs, but we're not 100% certain that SIRs are going to be in IT. At least most of us are not 100% certain.

I'm an advocate of a consistent IT rules set that is applied to the cars in IT without special allowances for certain cars. Maybe it is the scientist in me that likes consistency and logical order in the nature of things. In any event, the process the ITAC uses to class the cars was applied to all the cars in IT. Many adjustments were made and one car, only one car, was selected for special treatment. This one car was run through the process and would have weight added to it according to the model. But that was not done. Instead, it was decided that an untried technology in IT would be used to acheive parity instead of a simple weight solution.

This, my friend, is an inconsistancy in the application of the process and what a large number of people are upset about (and I do understand that the ITAC recommended weight as predicted but it was not chosen by the CR. Yours truly included. I don't care for the SIR, for sure, but the selective application of the process is what gets my goat.

[Bill Miller]

Joe,

You seem to be one of the only ones that think that it's not feasible to get a new IT class added. I'm not really sure what you're basing this on. I get the feeling that you don't want to accept a new class, as it would mean, in your mind, that SIRs were a failure. I think that's also one of the reasons why you think that a technology that hasn't turned a lap in IT yet, is "here to stay". You seem to have 'hitched your wagon' to SIRs, and will see it through, regardless. I'm really curious as to why you so strongly feel that SIR technology is such a magic bullet. And while I agree that close racing is important, I don't think you're going to excite a whole lot of people to go race cars when you tell them you're going to choke 25-50 hp off of the stock output of their cars. To me, I just don't see the point.