We are talking time attacks here, not a race Jean. I dont know what times Randy was running, but the record WAS mine at 1:36, granted I ran that at 3600 lbs, stock seats, basic JIC setup, Flash and ECU on scrub tires. So combine Randy Pobst with Al's car on fresh Hoosiers and it makes sense.

The record now belongs to a corvette that is world challenge fast, and I can assure you there arent many street cars that are world challenge fast. There arent any scrub records here in the southeast.

I'm fairly sure Randy wasnt running 1:31's or 1:32's at Barber. Even Al's car is outmatched by that Corvette at this point. I could beat it prior to the aero adjustments, but it's going to take something similar in aero before I can do it again. But that is in the works.


BTW, the class isnt technically unlimited, but draws the most competition because the real unlimited class is actually called TTR, and open wheelers/kit cars/sports racers can compete in it. TTU is only a 5.5/1 weight to power ratio with a severe penalty for AWD, so 6/1 weight to power ratio.

 

Nice info Al !!!

Randy Post was likely saying Al's car set-up is perfect for his intent.

Remember, Al still drives his car on the street occasionally.

A fully "tracked-prep'ed" car is no fun as a daily driver.

 

Jean,

Thanks for your comments but I think you are making an assumption that is not true. Randy Pobst never told me the car had perfect handling and I have never intimated such. I'm not sure where Heavychevy got that information but I assure you it was not from me. Randy actually said very little about the handling. His main comment was that it didn't feel like it pulled much better than the modified 996 he owns but he liked the 8K redline and found it helpful in some areas of the track. He never got to feel the acceleration with both turbos operating or his comments would've probably been different concerning the power. The difference between 1 turbo and 2 in my setup is 0.4 bar which is a significant amount of power.

I may have the NASA class designation wrong---it may not have been the unlimited class. I don't know those classifications very well as I have no interest in time trialing. Irrespective of whatever class it was, the record was the fastest of all the NASA TT classes at that time.

I was just in amazement at how much I am leaving on the table, so to speak. It increased my comfort level with the style of driving I presently do. In truth, he probably thought it felt like a fat unresponsive pig compared to the K-Pax Porsche he drives. Actually the weight was considerably more than 3700 at the time bc I was also in the car. I think the lap record was in the 1' 36" range at the time he drove it this spring and I believe it has now been placed somewhere in the 31's. Obviously the record wasn't near what it could be.

I would welcome any comments you might have about my setup. You have been helpful to others in your posts and I respect your opinions. I installed an HKS EVC VI this Spring and had my first track time with it June 7/8 at Road Atlanta. It was nice to have a low-boost setting for the track to help preserve the engine and driveline. I know the Hoosiers are stressing components but I do like the way they perform. I think the BF Goodrich R1 may be a slightly better performer but the diameter match is not as good as the Hoosiers in equivalent sizes. I run large Nitto NT-01's on the street and they are quite good at holding the high-boost power in straight-line acceleration which is my street-driving thrill.

 

Al, Neil and I were standing there chatting with Randy when you came off the track. I heard this from the horses mouth. I'm pretty sure you were standing right there too. You can ask Neil, but Neil kept repeating what Randy said over and over and over and over and over and over again so there is no way I could forget. In reference to the handling he said the setup was perfect (I'm assuming for the limit he was pushing it, which I did get to follow for a half lap when I saw your car on track in my group) and was able to keep up for that amount of lap. I do remember him saying the car didnt pull that hard and that was due to the broken actuator rod from what I remember. I dont know if you got those lap times on your driftbox, but from what I've seen, Randy takes it pretty easy at the DE's, especially in other people's cars. I followed him and we were running mid 1:40's for several laps, granted it was a 997S, and at Road Atlanta in his yellow 996 TT he was again mid-low 1:40's as I'm sure all the demonstration rides take a toll on him especially when jumping from one car to the next. Unless you guys miraculously found free space for some clean laps I know that Randy was being patient and waiting for point by's and sub 1:36's were not happening while waiting for point by's especially considering he came out towards the back of the pack. I was on old sport cups running 1:40 and couldnt get anywhere near a clean lap.

 

Al, are you saying that YOUR car has an 8k redline?! or Randy's modded 996.
Cause if it is your car you may as well not worry about a low boost setting for the track cause those rpms's will kill that engine.
If I misunderstood your post just ignore this!!

 

His car is 8k Redline, but the motor is built, there are quite a few guys here running a higher rev limiter in the 8k range.

And Randy's car is a 996 Turbo. But it's Al's car with the 8k redline.

 

Tom,

Pobst took advantage of the higher red line; I rarely do. Just because the engine will turn that high doesn't mean I have to do it. Most of my shifts are between 6500 and 7000. I log data from the boost controller and review boost and RPM levels via an on-board notebook and a pop-up single din touch screen VGA display that replaces the CD holder so I know what I have done on track.

Dez,

I don't recall any comments from Randy other than what I already mentioned. Not saying he didn't say it, just saying I don't recall. Randy's best lap IN traffic on ONE turbo was a very low 36.

Only my opinion that will never be confirmed but I believe my car, in the hands of a capable and aggressive driver, will contend with the Corvette. I don't know that I would meet the 6/1 factor but at my current weight on a Mustang dyno I think it would be conceivable. Who knows, the 'vette may not make the 5.5/1 factor if someone protested and challenged him to see the dyno man and the guy with the scales. When you get right down to it, the whole TT scene is a gentlemans integrity game. Sometimes the will to be #1 outstrips ones integrity. Think how easy it would be to cheat with an electronic boost controller.

 

Hi Al

It looks like your car is very well setup, which I am always happy to hear. Also good to know that you are using it as it should be!

I was repeating what I read from Dez but I think things got clarified now. My point was only that no one should think that a 996TT with almost full weight, DOT R tires and JIC suspension and 4WD is a track weapon. When you can get your 996 with 600BHP within 2 seconds from a well driven cup car, then you know it is well sorted. A very well sorted and lighter 2WD 600bhp 996Gt2 should be equal or faster than a Cup car in a time trial.

I doubt you will ever see a 4WD 996 being faster than a Cup except if you pay thousands to get a different 4WD system ala the RS Tuning/Alzen setup.

Funny I was watching today's practice sessions in Magny Cours for tomorrow's Supercup race. The first 15 positions are less than 1/2 second apart in qualifying!

The modified 996s with turbos are at a disadvantage vs. the corvettes when it comes to getting the hp/weight ratio right, reason being that depending how you are pushing it (boost and turbos), your car will be left with much less hp as soon as you have done a couple of laps at best. These dynos are not putting anywhere near real life load on the engine, so HP is overstated.

I went through the regulations of the NASA time trials, I like them and I think they have done a thorough job with the point system.

The current record is shown at 1.31 by a corvette.
Jean

 

Jean,

You are probably right about the disadvantage after a few laps. I don't think it's soaking at a track like RA but I'm sure there is a diminished output at some point.

Next event I think I'll experiment a little. I will analyze the 4th gear data and try to shift into and out of it at the same RPM and if there is a traffic interruption I'll mark it by tapping the brakes to invalidate that run. Will be interesting to compare the acceleration times on valid segments with the first 2 laps of the session. I have a test and tune day coming on the 4th of July with open track all day. That will be a good time to make the comparison bc traffic will probably be light.

Do you think that will give some valid data as to diminished output or do you have another suggestion for making a comparison? 4th is the only gear I can shift into and out of at a specific RPM point and I should be able to do it at approximately the same point on the track also. The lat/long data will confirm that part.

 

Al

It is not really about heat soaking only.

As soon as you put your car on the road and the engine has to push the car through its weight, rolling resistence and aerodynamic drag, the engine output will not be the same as on a quick dyno run, load on the engine is much higher in real driving conditions.

Heat soak then is another story that comes on top, after a couple of laps at full throttle going through boost and RPMs, if ambient temperatures are what they are in summer days, and you run above 1 Bar of boost, you datalogger will show you decreased performance by overlapping long Gs against each other lap after lap. If you run moderate boost, this will not be so obvious. Do you run stock intercoolers?

As far as measuring road hp vs. dyno hp. you can simply take your dyno sheet from the chassis dyno (rear wheel hp and torque, not converted to flywheel) and then extract the data from your datalogger and do a manual calculation of real hp and torque to the rear wheels based on the long Gs ( I can do that for you). You need to have the correct measured running weight available. This will also show you the impact of heat soak on performance lap after lap, if it is there.

If you are not full throttle/boost in your runs, it will be unlikley that you see this through datalogs.

 

I have never had the car on a chassis dyno bc for me, there was no real reason to do so. If, at some point, I make changes that should significantly affect power, I will baseline the car on an AWD dyno and then again after the changes. That's what I see as a valid use for a chassis dyno. Otherwise, I don't feel they provide any really meaningful data.

I do have after-market intercoolers from Bell. I do run full throttle at the track but the track setting for boost is 1.1. Street setting for what is mostly 1st and 2nd gear playng is 1.6 and that level of boost is over in just a few seconds. I'd be playing with fire if I ran it up through the gears at that level bc it would be a larger number than that in the higher gear and I really haven't experimented very much with the drop boost mode. The measurements are in kPa and have no number for number correlation with actual boost.

I appreciate the offer to do long-G analysis but the calculation of HP at the track is really not an important number for me. I will be getting a new weight number later in the year when I have weights and alignment checked to be sure everything is still where it's supposed to be.

I agree with your comments concerning AWD turbo and GT2 vs. cup car.

 

That's just it Al, I honestly dont beleive that it is in the 5.5/1 ratio. It surely is no even close when it's at max (~630 whp 2800-2900 lbs w/ driver = 4.6). Of course that's with a Dynojet. So if his car can make it, there is no doubt yours can too, especially with a boost controller.

It is definitely going to take some serious aerodynamic parts to beat that car, and or a Rolex spec or similar cup car to beat it, based on times alone, and lets not forget Reese is only about .3 or so slower than Cory Friedman in a Rolex Spec 997 Cup at Road Atlanta. Wth aero you could turn the boost up and still maintain your current straight line speeds or slightly faster while cornering and putting the power down much more efficiently.

It will take some kind of beast to run with that car. Yours has the potential, but given equal drivers, there is nothing the Porsche can counter the aero disparity with unless it's matched.

 

Jean, you'll have to be more specific with your well driven (pro driver?) and cup car (996, 997, specs) because there are a lot of tracks in the states where this IS possible. How about we start with RSR times and work backwards.

Road Atlanta

-RSR - 1:21 (Leh Keen) (PCA Race) 1:20-1:21 (ALMS)
- 997 Cup on Supercup tires (1:27) (PCA Race)
- 996 TT 550 bhp JIC MPSC (1:33) (this is mine with me driving in a DE)

I'd bet money Al's car on supercup tires can run 1:27. You cant compare non DOT tires to supercups because supercups are the best consumer non dot tire out right now. Same Tires and surely Al's car can run toe to to with a 997 cup even at near full weight. I'll be returning to Road Atlanta soon on Yoko slicks and I wouldnt put money against me running 1:29 or better. Now with 600 bhp.


I started with RSR times because the RSR's run the same spec in Lemans, FIA GT and ALMS. So the times should be pretty consistent. But Porsche Supercup doesnt have an equal spec class in the US so we cant compare directly.

 

Al

I was mentioning the test as you asked how to test it, there is no point otherwise I agree except if you want to know how the car is coping with the tune.

Dez,
Without getting into too much detail, when I say well driven Cup, I mean a good club driver, top 1-2 driving a 997 Cup. If Al's street car with JICs and stock weight goes as fast as a well driven Cup I will have to retire from this hobby sooner rather than later.

Leh Keen's is hardly a reference since his car runs without restrictors (and other changes). The 996RSR like mine is about 3-4 seconds faster than a 997Cup, and the 997RSR about 5 seconds faster per lap on our local track here. (driven by Pros)

I don't understand the Supercup tire comment, I guess you are talking about the Michelin S8 slicks.

 

I know Leh's car is difference hence the reason I included the ALMS cars because they are under the same regulations as FIA GT and Lemans.

But I have NEVER heard of a stock 997 Cup running 5 seconds slower than an ALMS spec RSR during race laps or qualifying, not a stock RSR testing. I'm talking about competition. And I have yet to see a 997 Cup 5 seconds from an RSR anywhere. 6 or 7 maybe.

The slicks here are called supercup slicks and is says SUPERCUP in big letters to differentiate it from the normal michelin slicks so I cant say for sure that they are the same.

Like I said, put Al's car on supercup slicks to eliminate the tire difference and the gap will be very small depending on the track. We are talking one lap here, not a race. On supercup tires I expect Al's car would be close to a 997 Cup for a time trial like situation.