Road Racing w/Forced Induction

[DrumrBoy]

Mine is basically a street car but goes to the track 5-6 times a year. I'm NA at the moment and wonder what the experience is out there among the road racers regarding the appropriateness/tradeoffs in going to forced induction.

Run sessions are often 20-30 minutes and the temps in the Southeast are generally around 100 in the summer, so stuff gets hot. Will a blower increase the onset of heat soak (yes, but by how much perhaps) and are there any problems with running a blower other than it getting hot and not increasing the psi charge optimally?

Also is there a difference between a Paxton or a Roe at reasonably low boost? Anybody run a Paxton or Roe on a road race car? Thoughts welcome.

 

[1BADGTS]

I just went thru the identical situation in wanting to build a Gen 3 Blower car.Though i dont roadrace alot of times my Vipers are used as test cars for Muscle Mustang and Fast Ford Mag.Their head test driver (Evan Smith) is known to be EXTREMELY ******* cars often hotlapping many times ect on very hot days.The more people i spoke with the consensis was that a supercharger in my application was not the best fit.The main issues were lack of space to put a large enough intercooler (heat soak and the issues it can cause)

 

[1BADGTS]

PS Drummer feel free to give me a call at 732-977-7244 i have the pros and cons list

 

[GTS Bruce]

In a car with a PUSH using stock setings and a lot of lean.Do you realy want to drop more weight on the nose? Why not Jm heads and cam? Looks like he is making 6 something na. GTS Bruce

 

[mjorgensen Woodhouse]

For the record the Viper can handle VERY well even with a Paxton on the front end, we have proved this many many times. If you are going to get serious about the performance of a S/C at a road course then the only option is a LARGE air/air intercooler system. This will prevent heat soak and retain power levels. I know Dan Craigin has built a couple of these and though the tubing and cooler fabrication is time consuming and costly it is VERY effective on the road course.

 

[RedEnuf93]

I'm not a "full time racer", but have been at Pocono's several times. I run the car HARD with Roe blower. Those who have seen this car at the track can verify that...
No heat problems with Ron Davis radiator, Autoform Le Mans front and Diamondback hood. NONE.

The reason I like Roe, is that the boost comes on VERY low RPM and makes even the old GEN 1 "enjoyable " to drive. There is no transition or lag, just smooth increase of power. I have the 8lbs pulley. The old Gen1 makes 541HP/620TQ with it. Stock motor, including stock heads with 52.000 miles on it.
Last time that power was enough to keep the Gallardo's, 430's, 360's, Ford GT's behind me. Before the flames start, yes, it was NOT a race, so I cannot verify how seriously they drived. Who knows, however I did about 150+ on straights so if they had more, they they held back.
Anyway, the car can be run hard at the 20 minute sessions with Roe. I do not see an increase of temp after 10 minutes, things stay pretty much the sam...I have never cooked or puked the system at the track. At the track I stay (remember its a GEN 1) around 200-220. I take the last lap on 5th or 6th to provide cooling with low RPM and good speed. At the time I pull to the pits, things are reasonably normal.

 

[TexasPettey]

It's all about what you want to do: Go Fast or Have Fun. I had a ROE on my Gen1, with GG heads, 708CAM, etc. making 600RWHP. I found that except on the very long straights, the power was largely wasted. Road racing is all about speed through the corners. Every MPH of speed you add in the straight has to come off with brakes. If you can brake later and hold speed in the turns, you'll be turning lower times. So $ is better spent on suspension and braking. Even with R compound tires, putting 600RWHP to the ground will seldom happen outside of a straight line. I went back to NA because the $ I had in the blower wasn't worth it for the track events that I was doing. Although, I'm still at 500RWHP.

If you don't care as much about time, putting 600RWHP down on the straight at 100MPH+ is very fun! Just don't let that Miata catch up to you on the tight turns.

Overheating can be helped with a better cooling system and ducting. Detonation is the big fear, so give yourself headroom on the tune for a bad batch of gas and extra heat. You'll lose some HP on the dyno, but you'll have margin for error. You can also buy some 100+ octane gas at the track to add to your margin.

 

[RTTTTed]

I went to HP driving school so I'm not an expert, however at half throttle I had no problemkeeping up to stock Viper, and every other car that was there.

I need much more practise at applying controls gently. I found it difficult to apply power slowly and 'easing into the power was also difficult. As posted above the Roe power is available at low rpm and small throttle openings. I also appreciated the 14" lightweight Roe brakes on the front of my car. I would slow down on the straights and allow some room to the next cars. At the end of the corners I was slowing again because I had caught up to the cars in front of me. PS2 tires are amazing.

No temp/heat soak issues noticed.

Ted

 

[DrumrBoy]

Thanks folks. I think I'll stay NA for the time being.

I was looking for a bit more for the street and straight line mojo but didn't want to sacrifice on the track. I'm not driver enough to use all the 560 RWHP on a road course as it is so the blower may not help me there.... just didn't want to run into issues on the track where currently I have non with the heads/cam set up.

 

[RTTTTed]

Less hp, less 'issues'. If there's only 400rwhp then you probably wouldn't lose much to heat soak. More hp = more heat.

 

[DrumrBoy]

Good point. Starting at 560, with an 8 lb pulley I might end up closer to 700 - which is what intrigued me for the street but maybe not for the track.

 

[RedEnuf93]

True, if you want to circle around cones, your better off with Miata.
In corners the SC will not help you, you need only 200 HP to do tight cornering (if that?), handling, brakes and HP control will give you the desired results.

Where I like the SC is at faster tracks, such as Pocono. Or at spirited canyon carving, it is PURE JOY.

I dont see the issue (at least for me) as NEEDING the power when cornering, tracking is only 0.1% (if even that) of my overall mileage. SC fits well at the track, but for the remaining 99,9% I can enjoy it at the streets, highways and long sweeping curves.

 

[Steve 00RT/10]

I agree completely with the 1% of total mileage statement. We do 10,000+ miles per yr. with 100 track miles and a couple autocrosses usually thrown in. The car will never be perfect for every situation, but I would much rather focus on the 99% of driving we do than the 1%.

Most Vipers and their drivers will be embarrassed by the likes of a Miata, EVO, Subaru, or S2000 on an autocross course. I've autocrossed with and without the Roe blower. It's a whole new game with the SC. Although every course is a little different. I think my times actually went up a little. Throw in a more negative PAX number due to the mods and unless you're an expert driver, you will be wiped up by much lesser cars...........But then, you don't have to beat these smaller cars to have fun. Our Belangered Viper is always the crowd favorite.

As for track use, I also completely agree with Texas Petteys take on speed into corners, braking etc. That being said, I've had absolutely zero issues with the SC on a shorter 1.88 mile / 11 turn track (Gingerman). With the blower, 3.45s, and light flywheel, I run the track in 4th all the way around now. There is no corner on the track I can't break the back end loose in 4th on track out and my 4th will pull a 3rd gear stock Viper (not 2008s). For the limited track use I get, it allows me to be much smoother, focus on the line more, and is much easier on the engine (1800-5000 RPM) Zero heat soak issues. One cool down lap and the gauge is between the 2nd/3rd bar. It has never gotten hotter than a couple needle widths over the 3rd bar.

As for how much speed one needs to scrub off, that's a function of your right foot. Tom's rear calipers, no prop valve, and light flywheel help manage that a little better.

Steve

True, if you want to circle around cones, your better off with Miata.
In corners the SC will not help you, you need only 200 HP to do tight cornering (if that?), handling, brakes and HP control will give you the desired results.

Where I like the SC is at faster tracks, such as Pocono. Or at spirited canyon carving, it is PURE JOY.

I dont see the issue (at least for me) as NEEDING the power when cornering, tracking is only 0.1% (if even that) of my overall mileage. SC fits well at the track, but for the remaining 99,9% I can enjoy it at the streets, highways and long sweeping curves.

 

[PhilC]

Some great posts here, I'm appreciating everybodys viewpoint. If I'm not mistaken the temperatures that of more concern regarding detonation would be the air temps post SC compression (not the engine cooling system temps). I have a Roe and I track the car a few times a year but I have been very concerned with how hot it is. I haven't experienced anything catostrophic yet thank goodness. Last time we tried to dyno tune the car, the nose cone seal blew and it was a mess but prior to that the intake temps were 150-160 which I thought was dangerously high. What air temp is everybody else experiencing and can anyone give me their opinion as to where the safe threshold is. Thanks in advancePhil

 

[99 R/T 10]

Hey Phil, after the seal blew, how hard was it to repair? Was it something you could do or did you have to send off the blower to get repaired?

 

[PhilC]

Well the funny part (not really so funny) is that I had sent it off to PSE in Oklahoma to rebulid the whole thing. The problem we were having was actually a nose cone problem. I did not specify that I wanted the nose cone assemby looked at as well so they rebuilt the entire upercharger except the nose cone. So we put it on the dyno and the seal blew. At this point we took the cone off and we think that perhaps the cone bore is not quite right. We staked (sp?) the seal in place and all seems to be ok, no more leaking for the time being we'll see when I try to dyno it again if it will stand up to the abuse.

 

[Steve 00RT/10]

I'm not sure how to measure post SC temps with a Roe. It would definitely be better for the post SC temp to integrate seamlessly with the PCM/VEC. Although the differences between IAT and post SC temps are not linear, they are somewhat relative as regards the AFR when using the WB set up to tune the car. My IAT has never gone above 125 or so. IAT monitoring on a dyno is not real life. I think log tunes are a better way to go. I always run a slightly richer tune on the track (11.2 to 11.5). I also stop removing fuel at 126 IAT. Our non Vipair car IAT is consistently 15-20 degrees higher. I have seen 142 degrees after a log run on a 100 degree day with the Vipairless car. The Roe blower was designed for 5 pound boost, which probably also makes it the most trouble free, easy to tune, and less worry about detonation.

I don't know what the safe threshold is, but I do know that stock Viper PCMs start to add a little fuel in for cooling when the temp gets high. I don't know that barrier either.

Steve

Some great posts here, I'm appreciating everybodys viewpoint. If I'm not mistaken the temperatures that of more concern regarding detonation would be the air temps post SC compression (not the engine cooling system temps). I have a Roe and I track the car a few times a year but I have been very concerned with how hot it is. I haven't experienced anything catostrophic yet thank goodness. Last time we tried to dyno tune the car, the nose cone seal blew and it was a mess but prior to that the intake temps were 150-160 which I thought was dangerously high. What air temp is everybody else experiencing and can anyone give me their opinion as to where the safe threshold is. Thanks in advancePhil

 

[PhilC]

Thanks Steve. Agreed that dyno tuning is not ideal. I really have to learn how to do the logging part. I keep thinking it would be great to add a couple more nozzles to the water **** system and shoot into the plenum as well as into the throttle bodies (cover both sides so to speak) Has anyone tried this and if so what kind of results did they have with it?

Phil

 

[Chuck 98 RT/10]

Thanks folks. I think I'll stay NA for the time being.

Good idea. Like RTTTed said, "less hp, less issues." And if there are any chances of issues they will arise road racing.

Dunno what your setup currently is, but I'd take a brake and wheel upgrade on a stock GenII over 100hp any day. And I'd get the Cone Brake Duct kit from JonB too.

JMO

 

[1BADGTS]

Phil your too nice a guy -letem have it BIG TIME!!!!!

 

[1BADGTS]

Phil (call me at 732-977-7244)I talked to Evan about this (thinks you got off easy with just the seal going )says it DEFINATELY needs what Nick is doing (inlet air temps way too high for your intended usage sooner or later will lead to bigger proplems )

 

[RTTTTed]

Road racing means you don't have a lot of room for passing. That sc sure makes the whole difference when you're pullin down on someone.


Ted

 

[1BADGTS]

Phil approx how many miles were on the blower when this seal went.Doesnt Roes warranty cover at least the part rebuild ect

 

[1BADGTS]

What is the exact reason every Roots blower Ford puts on one of their engines in cars or trucks like the GT,Lightening,Mustang has an intercooler.What is the exact reason The New Chevy Zr-1 Vette roots blower has an intercooler.

 

[1BADGTS]

PS i guarantee its not because these auto manufact have anything better to do with their money than spend it on useless parts like intercoolers.

 

[PhilC]

Hi Joe :

I'm out of town, actually just had a disaster with f350. Blew a head gasket and I'm 3 hours from home with a trailer.

Of course you are right on target with the intercooler and I just bought a hood that will allow us to do one which will make the system one that I can be confident in.

I'll give you a ring when I get home, if I can figure out how the hell to get home.

Phil

 

[1BADGTS]

Call me anytime(ill tell you what Evan said ) just be careful running in the hot weather untill Nick can figure a way to get some type of intercooler on that blower.