June Fastrack Out

*Grand Am allows 108db IIRC, that would make the exhaust on SpeedSource RX8's (GAC) illegal for IT. With what is done to them, and the design of the exhaust, it could not be cut to <103 without losing HP. How much HP loss..I could only speculate. Steve might know.

*I would not question the 232/238 rating. My understanding on the 232 is that is was a change in the rating system that year, and not influenced by anything else. If there is in fact a flaw in the rating, it isn't the 6 hp that changed that year.

*Open question for all. Does anyone have experience comparing crank(er flywheel) HP to wheel HP??? I don't. If you do, does 238 HP correspond to 173.xx WHP??? again, not a loaded question. I actually want to know.

*To Jeff's point about 1/4 mile times. Time is also dependent upon traction, driver, rollout, etc. Trap speed however, can be approximated mathematically, knowing only the weight and hp. There are more complicated programs available which also have inputs for gearing, tire height, etc. I would hesitate to use 1/4 mile ET's as an indication of HP-too many variables. Trap speed could be used though. Maybe I have a project for later tonight. :)

*Josh, no offense intended here, but when dealing with factory specs, there are errors. I deal with them on a daily basis. My company submits errors to the manufacturers when we find them. Most of them are easier to prove than the HP number though. (i.e. Saturn frame measurements off by 16 mm in the left rear) I realize that the factory is the best source for specs, but there are mistakes there too. If nothing else, perhaps SCCA should have a system in place for dealing with questionable specs.
 
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I thought the SAE adjustment was a "correction" by a governing body? Meaning that SAE mandated that everyone prove their hp numbers up. Some went up, some went down.

Why we aren't using the "corrected" number is beyond me.

On the 1/4 times, I was joking. I don't think we should be using that, tea leaves or the length of a pot and Budweiser induced burnout for classing a car.
 
As Josh posted the 238 is the only number the ITAC can use as a base and be respected. Where I see the problem is that we say we use the process and we do to a point. The process is then skewed by the "subjective" 15,25,30 expected gains. Further deviated from with the "subjective" -100 for low torque. It was just a guess or assumption on the part of the ITAC to assume a RX8 is like a S2000 so they gave it 15%. Might be right or wrong but it was just a guess. I have not seen any place in the discussion where it was justified any other way. It was just the lowest number used to date so there it is. Any data to state otherwise was poorly stated or in Kirks words irrelevant. He does not even remember listening to anything other than the stock number and what it meant. But in his mind the process was preserved. Right up to the SWAG. All data I have seen on the car says you were wrong.
 
Now that we're all being more reasonable:

Steve, you can't have it both ways.

We have to use the published hp. Thanks for seeing that.

Now, the multiplier is for the expected horsepower gain in IT trim. The proposal we got (with numbers from you) says that the stock horsepower on a chassis dyno is usually 165-175 (quoting from the proposal). Let's use 170, right in the middle of the range.

If we thought that the gain from IT trim was only 10%, that would mean you'd expect chassis dyno figures in IT trim of only 187 (170 + 10%). The proposal we got says that one of your cars with "some intake and exhaust work" showed 196 on the dyno. That's a gain of 15%. I personally would expect better from that once the specific combination of allowed IT mods is really targeted.
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Ok, Steve, just for the record, you think the car should weigh???

If I read your posts correctly, (and feel free to point out where I might have missed or misread something, I'm kinda busy these past few days), you think the math should be:

238 x 10% =262.8
261.8 x11.25 = 2945.25
2945 - 100 (tq) = 2845, rounded to 2850.

Is that what you expected?
 
Wait a second.

You say you accept 238 crank hp.

But you then use 165-175 whp to justify the 15% multiplication factor?

What am I missing here?

JoshS said:
Now that we're all being more reasonable:

Steve, you can't have it both ways.

We have to use the published hp. Thanks for seeing that.

Now, the multiplier is for the expected horsepower gain in IT trim. The proposal we got (with numbers from you) says that the stock horsepower on a chassis dyno is usually 165-175 (quoting from the proposal). Let's use 170, right in the middle of the range.

If we thought that the gain from IT trim was only 10%, that would mean you'd expect chassis dyno figures in IT trim of only 187 (170 + 10%). The proposal we got says that one of your cars with "some intake and exhaust work" showed 196 on the dyno. That's a gain of 15%. I personally would expect better from that once the specific combination of allowed IT mods is really targeted.
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And let me do clear up the proposal stuff a bit.

1. I wrote it. Steve offered to help out, and he revised certain portions of it (I don't remember which).

2. Steve gave me the dyno numbers I submitted with it, and I did some (admittedly internet) research on my own.

3. The numbers I came up with were mine. I then shared the proposal and dyno sheets with anyone who asked before I submitted to the ITAC.

After some discussion, I agreed with Dan, Grafton and others that the requested weight of 2720 or so was low.

I never revised the proposal to reflect that and I should have. My error.

Jake, your numbers below are precisely how I would class the car right now.

lateapex911 said:
Ok, Steve, just for the record, you think the car should weigh???

If I read your posts correctly, (and feel free to point out where I might have missed or misread something, I'm kinda busy these past few days), you think the math should be:

238 x 10% =262.8
261.8 x11.25 = 2945.25
2945 - 100 (tq) = 2845, rounded to 2850.

Is that what you expected?
Click to expand...
 
Yeah, I take it back.

Whether or not I believe the 238hp is irrelevant.

I'm just saying that I believe 15% gains over stock. I was trying to point out that apparently you do, too.
 
Dyno numbers are irrevelant. Too many variables. Too many different brands with inconsistent results. 170 on a mustang might be 210 on a dynojet.

Just my opinion.
 
JeffYoung said:
Wait a second.

You say you accept 238 crank hp.

But you then use 165-175 whp to justify the 15% multiplication factor?

What am I missing here?
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Jeff, that's the reason I was asking Steve whether Grand Am allowed any work that IT does not. He stated in his post on p.6 that the sheets he provided to the ITAC showed 196.68 HP for a full Grand Am build. He then went on to say a stock brand new RX8 made 173.25 HP on the same dyno. That's a 13.5% gain. It doesn't matter if the HP figures are corrected (or correct) or not, the % gain would be the same. If you plug 13.5% into the original equation, leaving everything else as is you end up at 2940. I don't have a side in this fight (my earlier smart-ass comment notwithstanding), but I think if you guys are going to argue a point you should at least be consistent.

I do think it would have been a good idea to have erred slightly on the light side - maybe have fudged some of those subjective factors a little - and get some of these cars on track, and then see if they needed adjustments. By leaning to the heavier side (I know, it's what the process came up with - never mind those subjective adders) you may very well never know whether this will be a good ITR car.
 
EoB! EoB! EoB! LOL...I'm kidding Earl......

But see, we keep mixing and matching numbers. Here, you are using a much lower than 238 crank hp number (the 173 at the wheels) to generate a gain factor of 13.5% and then APPLYING THAT TO THE VERY SAME 238 CRANK HP NUMBER YOU JUST REJECTED. Sorry, don't mean to yell, just trying to be clear.

In other words, if you are going to use 173 and 196 to generate the gain factor, then you HAVE to apply it to what, 210 stock crank hp (that's about 173 wheels right), to get a "consistent" weight.

Isn't that right? Or am I missing something?

erlrich said:
Jeff, that's the reason I was asking Steve whether Grand Am allowed any work that IT does not. He stated in his post on p.6 that the sheets he provided to the ITAC showed 196.68 HP for a full Grand Am build. He then went on to say a stock brand new RX8 made 173.25 HP on the same dyno. That's a 13.5% gain. It doesn't matter if the HP figures are corrected (or correct) or not, the % gain would be the same. If you plug 13.5% into the original equation, leaving everything else as is you end up at 2940. I don't have a side in this fight (my earlier smart-ass comment notwithstanding), but I think if you guys are going to argue a point you should at least be consistent.

I do think it would have been a good idea to have erred slightly on the light side - maybe have fudged some of those subjective factors a little - and get some of these cars on track, and then see if they needed adjustments. By leaning to the heavier side (I know, it's what the process came up with - never mind those subjective adders) you may very well never know whether this will be a good ITR car.
Click to expand...
 
erlrich said:
Jeff, that's the reason I was asking Steve whether Grand Am allowed any work that IT does not. He stated in his post on p.6 that the sheets he provided to the ITAC showed 196.68 HP for a full Grand Am build. He then went on to say a stock brand new RX8 made 173.25 HP on the same dyno. That's a 13.5% gain. It doesn't matter if the HP figures are corrected (or correct) or not, the % gain would be the same.
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that's an astute observation worthy of repeating.

Steve....what else besides sound is different in grand am compared to IT?
 
JeffYoung said:
EoB! EoB! EoB! LOL...I'm kidding Earl......

But see, we keep mixing and matching numbers. Here, you are using a much lower than 238 crank hp number (the 173 at the wheels) to generate a gain factor of 13.5% and then APPLYING THAT TO THE VERY SAME 238 CRANK HP NUMBER YOU JUST REJECTED. Sorry, don't mean to yell, just trying to be clear.

In other words, if you are going to use 173 and 196 to generate the gain factor, then you HAVE to apply it to what, 210 stock crank hp (that's about 173 wheels right), to get a "consistent" weight.

Isn't that right? Or am I missing something?
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Not so much missing anything Jeff - well, except maybe that what I'm saying, and I think Josh was alluding to also, is that the actual numbers don't mean as much as the difference between numbers from the same dyno. And in reality, we all know that even those numbers aren't all that reliable; if they came from different cars, tested on different days, with different operators, etc. they may or may not be truly representative. That's why Andy's point about only using real world data when it comes from many different sources, over a sufficient period of time, is absolutely spot on IMO. One set of data, no matter who it comes from, isn't enough to rely upon when setting the weight of a new car.

And, I would bet a paycheck that under the right circumstances you could put an engine on an engine dyno, pull 238 HP, then turn around and drop it into a car and only see 173 HP on a chassis dyno. There are just too many variables involved.
 
tnord said:
that's an astute observation worthy of repeating.

Steve....what else besides sound is different in grand am compared to IT?
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http://grand-am.com/assets/KONIRules.pdf

7-5 Exhaust System
7-5.1 All catalytic converters must be removed unless otherwise stated.
7-5.2 Exhaust pipes must exit behind the driver; extend to the perimeter of the bodywork and direct exhaust gases on a minimum of 45 degrees down.
7-5.3 The exhaust system on naturally aspirated cars is free beyond the OEM exhaust manifold except as noted in 7-5.2.​

7-7 Other Items Which May Be Substituted​
7-7.1 Spark plugs, wires, distributors, ignition wiring and batteries. Batteries must be of the same dimensions as OEM battery.
7-7.2 Filters, fluids, lubricants

7-7.3 Belts, pulleys, hoses, wiper blades
7-7.4 Inside mirrors, fittings, nuts, bolts and fasteners
7-7.5 Gaskets, bearings, piston rings. Replacement head gasket must be OEM thickness.
7-7.6 Fuel pressure regulators and fuel injectors
7-7.7 Radiators​



7-8 Engine

7-8.1 Engine management systems may be replaced with non-OEM systems with Grand-Am approval. Effective 01/01/08 all GS and 05/01/08 all ST KONI Challenge cars that choose to use an aftermarket ECU must use the Grand-Am specified ECU and wiring harness. Spec ECU and wiring harness’s cannot be modified in any way.
7-8.2 The following components may be tooled enough for balancing only - pistons, rods, crankshaft, harmonic balancer, flywheel and clutch.​


7-8.3 The lightest rod and piston must remain unaltered.
7-8.4 The crankshaft and harmonic balancer may weigh no less than the OEM specification.
7-8.5 Aftermarket pistons may be used provided they remain identical in weight, dimension and form.
7-8.6 Allowed to overbore block up to .030 maximum.
7-8.7 The oil pan and oil pick up may be modified (not the pump)
7-8.8 Engine oil Accu-sump system and valve is permitted
7-8.9 All pushrod engines may use aftermarket blueprinted or adjustable length pushrods, provided they are of the same material and configuration of the original.
7-8.10 Other items that may be replaced include cam gears, sprockets and chains.
7-8.11 The airbox and air filter are free on normally aspirated cars unless otherwise specified by Grand-Am. Ram air induction is not permitted.
7-8.12 Grand-Am will provide restrictors when required.Teams will be responsible for gaskets and bolts to attach the restrictors.​


spec line:

Mazda RX8 2004, final drive: 5.12:1, fuel cap: 17.9, weight: 2650​

Tire size: 225/45/17. RPM limit TBD. MAZDASPEED aero #QSEA-50-020-X1, QSEA-51-96Z and QSEA-70-900-X1 are allowed. Allowed exhaust header. Allowed oil cooler vent in trunk. May use aftermarket ECU.​
​
​


 
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