Forced induction and Road racing

[KillrStang]

I would like to have some insight on what some of you guys are running at the track, besides the suspension side of it.

Here is my view point on the 3 types of FI

Turbos- HEAT, Heat, heat, i believe cooling is the only problem with them at this point. best looking power curve tho..

Centris - Great progressive curve, but there is a problem of weight and also the drag it as on the motor.

Twin Screw - I honestly this is my least likely pick for a road race car, being that heat soak is going to eat your hp. also even tho it has awesome low end, in a corner it might provide a problem with too much over steer.

 

[Sleeper_08]

I would like to have some insight on what some of you guys are running at the track, besides the suspension side of it.


Twin Screw - I honestly this is my least likely pick for a road race car, being that heat soak is going to eat your hp. also even tho it has awesome low end, in a corner it might provide a problem with too much over steer.

I run a Roushcharger and it does require "throttle modulation" at times, even with 275/30/18 Nitto NT01s

When I built my car I was determined that if I could stay with them in the corners then they were not going to out drag me down the straights. There is not much that can, though these days 400+ HP is almost de rigueur!

 

[stkjock]

one needs cooling upgrades to overcome the heat soak issue.

"pcdrj" runs a Saleen on his road racing car, IIRC he's got a lot of cooling upgrades and the motor was detuned some from peak to make it more road course friendly

 

[jymontoya]

Saleen 475hp kit here. 404whp/400wtq on very safe tune, Thank you Kurgan Motorsports! No issues so far, but it was ONLY 80* my first weekend out in this car in March! IAT stayed below 140*, and made great power during the 25min sessions. Just normal Saleen kit cooling, though I added an AFCO Radiator, as these cars, even in N/A form can overheat regularly on the track.

Honestly, the car was hotter, in both IAT and Oil temp in the moments waiting on grid than any other time, even after coming off the track hot.

I will wait to see how it does in 90* heat, but I suspect it'll be fine for my current 'just having fun' purposes. If I see the IAT's get above 160*, I'll consider a better Intercooler Reservoir (Saleens biggest cooling weakness). Then a larger Intercooler would a worst case scenario. The normal Saleen Dual intercooler system really helps mitigate the heat, especially when you're moving at high speeds on the track. FYI, the Edelbrock also uses the same system, as it was designed by the same person(s)?... Wish it was around when I went FI... be nice to have my Bullitt STB on there, even if it is just for looks. Looks good on the wall of my garage too though.

I will tell you that with this much torque, you have to be careful on corner exit. It's totally manageable though with good throttle control. Something that's important to learn anyway. The big flat torque curve (See below) of the twin screw makes it really easy to drive, and you don't have to rev the snot out of it to be very fast. 6000rpm shifts are plenty.

While I truly love my Saleen, If I were going to do it over again, I'd probably of given the Rotrex (Forced Air) kit a shot. Good torque curve, and really simple installation. Could be more easily undone... I may still go N/A one day depending on where I go, and if I take this car along for the ride. Right now, it's an incredibly fun toy car, but wouldn't be an ideal race car. Keep your end goal in mind when you're building... My cars purpose changed from daily driver to weekend toy when I took a job 60+ miles from home. Now I drive the crap out of a little TDi during the week. (Still gets 41+ mpg with me driving!)

 

[KillrStang]

^^^^ the rotrex kit is the same one that the CCX has right? it would be sweet to have a twin centri kit much like the CCX ( 4.8l twin supercharged with 1080hp)

 

[19COBRA93]

I loved my Rotrex setup on the road course (and in general as well). It felt like a big cube n/a motor. In fact, I liked it so much, I recently sold my Procharger and went back the Rotrex. However, just like most of the others, heat soak was an issue. A big Shelby heat exhanger/fan setup would take care of that though.

A twin Rotrex setup would be sick.

 

[knownukes]

I run a KB water cooled twin screw and make in excess of 650rwhp. I have had this setup for 2 track seasons now. I also run the Shelbly/Revan Racing twin fan radiator and intercooler that is manufactured by C&R. As long as ambient temps are below 85 degrees I can run as hard as I want. Once it gets hotter than that, I need to watch water temps(I watch it more than anything else) and occasionally back off to 8/10ths for a lap or so and then get back in it. It confuses people sometimes because I will blow by them, then wave them by and blow by them again. It is manageable and only impactful when it is really hot. In the spring and fall I really don't have any issues.

As far as getting the power down. It was very difficult when I had the Eibach suspension on the car. Once I put the full GRIGGS rear end on(torque arm, watts link and Koni coil overs), I have minimal problems coming out of corners. Oak tree at VIR is a little tough, but no issues at RA, SPR or Sebring.

I run 295 R6's all the way around.

The proper cooling setup is key. The big push is the back is a blast, but if I had it to do all over again, I would a hi hp NA motor. The Boss was not out when I bought my Shelby, so it was really my only option at the time. You are also going to have to run race fuel. Another big cost. Or run the risk of a hear related, predetonation motor blowup! Keep that in mind as you are making your decision. I know a couple of people that have blown FI motors and the tear down showed it was due to heat/predetonation. Race fuel solves that problem, it just hurts at $7+/gallon.

Hope that helps.

BJ

 

[Sleeper_08]

For extra cooling you can always use the old trick of turning the heater on at full speed at max temp.

 

[jymontoya]

For extra cooling you can always use the old trick of turning the heater on at full speed at max temp.

X2... I always leave the side vents pointed up and out the windows (centers closed), and the temp switch on hot in case i need to turn on the fan to high during a run. I know a guy in an 2006 GT that has to run like that all the time. It's what prompted me to go ahead and get the AFCO radiator. That, and S281 Motorsports had them on sale for $375!!!

Running 93 Octane here... Will not go to race fuel unless the temp gauges suggests its needed. But my paltry 404whp is nothing compared to his 650+whp!

 

[Whiskey11]

Would the Saleen Supershaker mitigate any of the IAT heat soak issues? I would imagine that pulling all the air directly from outside would keep IAT down considerably in a racing environment, it may not do anything to keep the actual supercharger from getting to hot though...

 

[19COBRA93]

IAT's are more effected by the intercooler/heat exchanger efficiency. So the super shaker will not make much of a difference, especially when heat soaked from a road course.

 

[Thekid760]

I've been debating this for awhile now. I want more hp, but can't really gain much more without going full-tilt. So I'm debating my options and the 2 that are on the top of my list are:

1) N/A - 298 11:1 stroker, stage 3 heads, spr cams, JPC intake manifold. 1 3/4-1 7/8" headers. but 4.10 would prob be required and thus cause the need to go into 5th at some tracks, and still not be at 500whp.

2) Turbo - 9.0:1 298 stroker, stage 3 heads, custom turbo cams, JPC intake manifold, and lower boost. still need largest intercooler I can find, alum radiator, ps & oil cooler.

I can always turn the turbo up for the street, but not so much NA. Thoughts, ideas?

Either way and expensive build.

 

[Godzirra]

Instead of a expensive motor build, might as well get a boss and do full boltons and have over 450whp n/a. Strip your current car for all that is transferrable.

 

[Kobie]

I loved my Rotrex setup on the road course (and in general as well). It felt like a big cube n/a motor. In fact, I liked it so much, I recently sold my Procharger and went back the Rotrex. However, just like most of the others, heat soak was an issue. A big Shelby heat exhanger/fan setup would take care of that though.

A twin Rotrex setup would be sick.

Glad to see your back with the Rotrex! I still love mine!
Is this the heat exchanger you are talking about? Kinda pricey at $799. Do you think this is the best model on the market?

 

[Marc s]

I prefer Centris for road racing due to the predictable power delivery. I make 735whp and find it very manageable. My IAT's are between 106-112 degrees. The weight bias on my car is 52% on the front and 48% on the rear. If I am coming out of a slow 2nd gear corner, I can exit at full throttle by short shifting into 3rd. A twin screw or turbo at my power level would be a handfull.

 

[knownukes]

I prefer Centris for road racing due to the predictable power delivery. I make 735whp and find it very manageable. My IAT's are between 106-112 degrees. The weight bias on my car is 52% on the front and 48% on the rear. If I am coming out of a slow 2nd gear corner, I can exit at full throttle by short shifting into 3rd. A twin screw or turbo at my power level would be a handfull.

What suspension are you using? My dyno # is 700.4rwhp with the Kenne Bell 3.6 LC S/C. My weight distribution is not that good. I'm not home to check my file. But managing the torque(651ft-lbs) comming out of slow corners is not that hard. My IAT's run about 108-120 when it's hot outside. I use water temp to know when to backoff a little. What fuel do you run?

 

[Dreadknought]

This thread makes me wet...

 

[Marc s]

What suspension are you using? My dyno # is 700.4rwhp with the Kenne Bell 3.6 LC S/C. My weight distribution is not that good. I'm not home to check my file. But managing the torque(651ft-lbs) comming out of slow corners is not that hard. My IAT's run about 108-120 when it's hot outside. I use water temp to know when to backoff a little. What fuel do you run?

K springs, D Specs, control arms with rod ends, and I have a GT500 rear bar. Having a fuel cell in the back helps with weight distribution. My 735whp tune is my pump gas tune. However, when I'm on a road course, I mix pump with 101 octane.

 

[KillrStang]

I love this forum you get alot of insight

 

[kevinatfms]

im sticking with a n/a setup but it seems i make enough power to keep up with most of the FI cars in the low 400whp range due to weight.

im running heads/127200 cams/c&l intake and so far with it untuned ran 352whp running very rich at the top end...going in for a dyno session with HP tuners and hope to pull off 370+whp and clock the car in around 3250lbs or less with me strapped in.