Painrace

Aaron, I see you went with a vented hood. Did you remove the fans first? The fans actually block and reduce air flow above 35-40 MPH.

Jim

Aaron Pfadt

Diffuser!

We had the fastest car all weekend. It is a real testament to engineering. We were out there with a stock LS7 and no wing and took TTU (Time Trial) and had the race for ST1 sewn up when I was punted on the last lap.

The video is great to see. I'm editing it right now and will post it with a full race report later today.

Thanks for all of your support.

Aaron

Aaron Pfadt

Yes we did (both). I actually put on a small Spal fan in case we ran under caution or had the race red flagged. We did a bunch of things to make sure the car ran cool and they paid off at the end. We'll have to go sort things out and try to make sure what mods are the 'keepers'.

The hood was good for about 15 degrees of water temp. The fan replacement was probably worth more than that. We did other things at the same time we did the fan change so it is hard to know an exact number.

Thanks for the advice on that.

Aaron

bobmac427

Not to deminish your accomplishments but Danny Popp would have probably won in a Toyota.
Congrats on a great weekend.

Mac

bowtiguy

you can see V.1 hood here...

http://forums.corvetteforum.com/auto...8-22-23-a.html

Looks like a different hood in this thread ( 2 center vents VS. 3) not just a flat black rattle can job.

Aaron,

Will that diffuser be bolt on for track days??? I can't imagine driving to and from work with that installed. Likeise I donlt want to look like "wingo" from the cars movie

Painrace

That is GREAT to hear. I am asking for me too. My car is a street car and if I have temperature issues I have to go with a vented hood. 15 degrees of water temperature is a ton.

I did not have a fan on a race car for almost 30 years. I sat through many red flags (and caused a few myself) and never had any heating issues. At pace lap speed you are fine.

We got a squirrel cage fan out of an old AC unit and mounted it on a piece of plywood so it sat on the ground in front of the car at the right angle so it blew into the radiator and it kept the car cool in 127 degree temperatures in Abilene, TX while we worked on the engine in the paddock area. Just be sure you get one that has the motor internal and no belts to get fingers caught in. We also placed wire on the intake of the fan to keep little fingers out.

I am looking forward to the video.

Do you know how to have the guy behind you hit you and cause him to spin out and you keep going? It is really very easy!

Racing is a contact sport and the guy behind you will have all the trouble!

Jim

MTIRC6Z

Aaron, is it possible to quantify with any degree of accuracy how much weight is saved by using that Lexan rear window?

Cheers, Paul.

PS...and Jim where you at with your car these days? I see Aaron is using the rear spoiler you plan to, which is making me wonder about my decision :-)

Painrace

Kevin at Katech is still working on their aero parts on it. They hope to have it to the wind tunnel soon.

If we get it to the wind tunnel in time I will take it to the Petit at Road Atlanta.

Jim

RoatanMan

Sweet!

Aaron Pfadt

Paul,

I'll look into this. I know we weighed all of the parts as they came off the car.

From our spreadsheet, the front glass weighed 32lbs and the lexan weighs 13lbs. That is a savings of 19 lbs for the front.

The rear glass weighed 23 lbs and the lexan is about 10. I do not have an exact number. That should be another 13 lbs. It is not a huge savings, but it adds up and is up very high on the car.

-Aaron

Aaron Pfadt

It's a production hood modified for testing. We're getting the cooling dialed in and then we'll decide what to do about a 'real' hood. Most of what is on the market is for looks only, not functionality. The World Challenge hoods are designed for cars with flipped radiators and most of the vents are too far forward (to do any good with a standard radiator placement). We have also learned that vents too close to the windshield let air into the hood (ala cowl induction) rather than out. That is not good for cooling either. You can see the last version of the hood has the rear two vents filled back in.

The hood in these photos is still the blue one, we just covered it with a CF look sticker because it was quicker than paint and we were running short on time.

It should be able to be bolted on and off. This one is and the production parts will be similar. The trick is obviously the mufflers. Ours are in the tunnel . The diffuser will be a relatively large kit because it requires some re-arranging of components. We are looking into the possibility of having the strakes be flexible so that if you drag them on teh ground they do not break or get ripped off. Stay tuned for more on that part. It sure works awesome. We'll be quantifying lift and drag numbers on it and doing some optimization before production.

-Aaron

Aaron Pfadt

Race Report : NASA Nationals 2009 Miller Motorsports Park, Tooele, UT.

This year as most of you know we have developed our C6Z into the new Pfadt ST1/TTU car. There are several threads on the forum detailing the build of the car and the philosophy of the build.

I did not run enough TT events this season to qualify for the TTU National event so I invited Danny Popp to co-drive the car in TTU. I drove in ST1 wheel to wheel.

The car has been working well (this is only it's third race weekend!) but we still had some bugs to get out. The weather has been warm and cooling has been plaguing us. For TT that did not turn out to be an issue because the sessions are short and the fast laps come early. Heat soaking on the engine and traffic conspire to make the later laps less productive.

In the ST1 races, the heating turned out to be formidable. The format for the racing was this. We ran a qualifying race on Thursday, a qualifying race on Friday and the final race on Sunday. The finishing positions of the two qualifying races determined my starting position for the final race.

On the Thursday race, I had qualified on the pole (in fact I had the best qualifying lap of anyone in our run group). Things went well in the early stages of the race. I beat Tom Glenn in the Viper (who turned out to be Danny and mine's best competition all weekend) at the start and led the first 5 laps of the race. My Z then started to overheat and I had to back off and let Tom by. It went even worse from there, I pushed out enough coolant to get an air pocket in the system. The temp spiked and sent the car into limp mode, shutting off half the cylinders. I pulled off just before the last lap and watched the race end from the hot pits. I was disappointed to say the least. The car was clearly the fastest in the field and I DNF'd because of cooling.

Danny had better luck on Thursday and threw down a blistering 1:57.8 lap setting the tone for TTU.

We worked on the cooling and changed a bunch of things on Thursday night to be ready for Friday. We decided to keep the car out of TT for Friday in order to concentrate on the cooling issues. On Friday warmup and qualifying, the car stayed cool and we thought that the issues might be behind us.

Unfortunately, the race was pretty much a repeat of Thursday's race and I started from the pole and led until I overheated and let Tom in the Viper by. This time I stayed out and fought the 'limp mode' and brought the car in to a second place finish just barely holding off the second (red) Viper driven by Mark Alger. It was quite a challenge, I had to key off the car on the straights and restart it to get out of limp mode. On top of that each time I had to hold down the active handling button for 10 seconds with my right hand to disable Active Handling/Traction Control. I did that like 5 times. Try shifting, steering, restarting, disabling AH/TC all while holding off a Viper. It was not pretty!

Saturday was a day for Danny to recapture the TT lead (Tom in the Viper had put down a 1:57.5) in one of the sessions. We had an issue with the Tire Pressure Monitoring System in the first run session of the morning and that cost Danny a session in the cool (read as fast) time of the day. Neither of us were happy. I am absolutely furious with GM for not offering a real fix for that system for racing. I am not willing to put sensors in all 5 of my sets of wheels. What happened is that the battery got disconnected and the system lost the sensors and was in 'Flat Tire Mode'. We have a battery cut in the car to be legal for ST1 and if you shut it off, the TPMS goes nuts. It is insane to deal with. In 'Flat Tire Mode' the car will not go into AH/TC disable and the car is un-driveable on the track. Rant off.

We also worked hard on the cooling system on Saturday because we knew we had to change things to win on Sunday. I do not mind being beat in a fair race, but I do not want to go out with a cooling problem. This time we removed the GM fan shroud and installed the Spal fan from my C5. We also added two more oil coolers (air to oil) to the nose and cut big holes in the nose to match. During all of this, Danny was able to put down a 1:57.4 edging out Tom in the Viper in TTU by .01 second for the overall lead.

Sunday morning brought cooler temperatures and some clouds in the sky. That is good for our cooling system, but we still had not tested all of our mods in a real race. Warmup went well and the cooling system worked for a 20 minute hard run. That was not conclusive though, because in the previous mornings it had worked for 20 minutes also. The heat of the day would be the test, and that would be the race.

I was gridded 4th in ST1 and we ran a combined start with SU/ST1 and ST2. We were ordered by class, but we all took the same green flag. I was about 10th on the grid overall. My main competition Tom was 4 spots ahead.

The video will tell the story better than I can, but I'll give some highlights. I did OK on the start, but could not better the Viper and was behind him. We had two successive full course yellows for a total of about 4 laps that ate up much of our race time. On the second restart I followed the Viper for a couple laps and then was able to pass him for the lead. That lasted for a few laps and he passed me back. He was turning very fast laps in there and the both of our cars were great. Nearing the end, we got caught by two ASC cars (different class) and they got into the mix because our lap times were very close. At that time the Viper seemed to lose some speed and we bunched up. On the last lap I was on Tom's bumper and he went wide in a turn. I went under him in a clean pass and he went off the outside of the track. When I was next to him, he spun and hit me very hard (the video shows this well). That put me off and into the gravel trap where I was stuck and lost the race. Had I been able to stay out of the gravel I could have finished and maybe even still won (we were quite far ahead of the next ST1 cars). I got pulled from the gravel and then drove the car in after the race was over.

It was disappointing to have the race in hand and be taken out on the last lap. That said, out car was very fast and I can not be disappointed with that. We won TTU (thanks again Danny!) and showed that a stock motor Z06 can be competitive in ST1. You can see in the video that my advantage over the Viper was certainly not motor We'll be back next year and we'll give 'em hell again.



Start:


Middle:


End:


Enjoy!

-Aaron

Aaron Pfadt

On the Dyno after Danny's TTU winning 1:57.4 run



Adding brake cooling on Sunday morning



Big oil coolers



Danny running TTU Sunday Morning



On the grid before Sunday's Final Race



The aftermath

Poor-sha

I love to see all this real world racing and development on a production car - great work and great results! It looks like the diffuser held up well.

Aaron Pfadt

Yeah. Keeps the car straight in the gravel trap!

-Aaron

Frenchican

kentz06

Damn Aaron that sucks!!! Did he T-Bone you with his front end darting back on the track? Body work looks beat-up, how did the suspension and frame holdup?


Best looking potato planter I've ever seen!

[/QUOTE]

A little more HP and it would be by-by Viper.

Great driving from you and Danny, as usual!

Dean

dvandentop

whats speeds do you see on the front straight at miller? also looks like you went with stoptechs all the way around, what is the pad of choice?

Joe_Planet

viper... what a douche!!! was probably boiling his brake fluid and decided to do a powerslide into your side. what kind of brakes do you run on the track? how do you like them?

Aaron Pfadt

He actually hit me with his passenger rear quarter. He was spinning (and backwards) when we made contact. It was not a case of malice, he just lost it in the gravel and spun into me.

The damage is mostly cosmetic. I need a new door, rocker and rear fender. The new silver rear fender is in my office right now courtesy of Corvette Recycling. They are looking for a door and rocker. The suspension needs more inspection, but has a bent toe link at least. The car drove OK, so I think that the damage is minor. The door opens and closes fine, so I think the frame is OK.

We were running about 155 at the end of the straight. That is where the low 460 hp hurts us badly. You can see how hard the Viper pulls us on the front straight. It is part of the reason I went with the low drag diffuser setup rather than a full wing.

I put on the Stoptechs from my C5 race car because the factory Z06 parts would not work. They are only a stopgap until I put in something else. They worked, but were on the edge the whole time. I bled them between sessions with fresh Castrol SRF ($80 a bottle) and kept thick pads in them for less heat transfer. They got soft a couple of times over the weekend. I ran Hawk DTC-70 pads. They are good pads. I tend to prefer PFC-01 pads, but Hawk sponsors Danny and they are good pads also.

This car with it's weight and slicks needs something larger than a 355x32 rotor. I can fit a 380 under all my wheels so I will be going that direction. We already have maxed out the cooling with full ducting and rotor backing plates.

He was boiling his brakes, we talked about it after the race. He went wide and spun into me. I think it is interesting that he lost his brakes. That Viper is well sorted and well driven in general. I think I was pushing him much harder than he normally has to run and he cooked his brakes. It is a testament to how well our Z06 was working. I was having no brake fade at all in this race.

-Aaron