CJarrett

Over the years there has obviously been a lot of turbo charged cars raced. On the road, the difference between a high hp turbo car, and a high hp NA car has a much bigger difference in speed and driveability simply because of the type of driving done, but how does it differ on a track in your opinion?

Is turbo lag ever much of a problem on the track? Normally you would be able to keep your turbo on boost on a track, but does the spool up ever become an issue?

I think longevity can be a problem with turbos, definitely more to go wrong there, and when something is wrong, it seems like it could lead to a larger problem compared to if you were running NA.

Love to hear what you racers think.
Carl

gracer7-rx7

iTrader: (16)

Lag isn't the problem with running a turbo motor for a road race car. Heat, development time and money toward managing heat and fuel management, usage, costs are the factors. If you have heat and fuel solutions properly engineered and managed, longevity is less of an issue as even NA motors used in racing will fail quicker.

wrankin

Heat, heat and heat. Those are your three big problems with turbos on the track

That and the fact that with a more complex system, there is simply more to go wrong. In this past season of the Speed Channels reality series, "Setup", the biggest single reliability problem the teams seemed to face were boost leaks, either from hoses blowing off or (as Mike Skeen got bitten by in the final race) intercoolers getting cracked.

-bill

Turbo23

iTrader: (4)

I think, with all the time and money used to build a "reliable" turbo track car, you would be able to build a decent 20b NA car, and have alittle less heat, and no boost issues.

CJarrett

Yes, thats what it seems. With a turbo car, the power comes easily(cheaply), and then spend the money on reliability and heat, whereas the NA power is more expensive, but more reliable and requires less effort to keep it that way.

What about driveability. Would it make sense to have a twin turbo race car, or a single turbo, if you were using a 2 rotor that is.. I mean, the lag with the single turbo shouldn't make much difference in driveability on the track would it?

j9fd3s

iTrader: (3)

if you're under 4000rpms roadracing, theres something wrong. lag is not really an issue, in fact you may want a little.

a twin turbo is just an extra turbo to keep cool, unless you're after something like howard coleman.

TrentO

I run a heavily modified 1988 Turbo II as a road race car. Yes, heat would be an issue if you try to run stock components. My biggest development hurdles to date were around getting an efficient turbo setup and controlling the oil overflow. My car has run hour long events, driven hard, without issue. If you want a turbo car you can run hard you need a big radiator, well ducted and a good low restriction turbo system. I'd also push hard on the fuel system side, with parallel rails and a good stand-alone system.

My setup:
Afco 26"x21" circle track radiator
Microtech LT-8 EMS
A-Spec GT-35R turbo kit
1600 cc secondary injectors and 550 primary injectors in a parallel fuel rail setup.
Walbro 255 fuel pump
Hardened stationary gears
Racing beat lightweight steel flywheel and dual disk 7.25" clutch
Low compression 1987 rotors
Rotary Aviation apex seals
Solid corner seals
No front cover gasket
Custom oil overfolw tank
Custom front mount intercooler, and hose, all secured with T-bolt clamps
Bilstein EP shocks w/ remote reservoir in rear
550 inch/lbs springs up front
375 inch/lbs springs out back
Suspension techniques sway bars F&R
Seam welded chassis with full roll cage
AWR rear camber adjusters
Full delrin suspension bushings, inculding toe steer eliminator
Cryo treated rotors
Carbotech Xp12 brake pads
3" brake ducting
1" widebody front fenders
17x8 and 17x9 lightweight aluminum rims
235/40/17 tires up front. 275/40/17 out back
Kaaz 1.5 Limited slip differential
Custom wiring harness, all breaker based (no fuses)
Fiberglass rear hatch (Jgrewe built, awesome job BTW)
Fiberglass hood (Jgrewe again)

Here's some photos of the build:
www.rxracing.com

In summary it can be done, but it takes a lot of time and effort to build it to last.

enjoy.
-Trent

Dan Unk

iTrader: (7)

I started tracking my Turbo FC back in 05, and every time I took it out on track a problem would crop up. Oil temps were the first, followed understeer and then on to brake pad selection and brake cooling issues. If you noticed these problems have nothing to do with the turbo system at all, as a matter of fact thats the only thing the first weekend that didn't give me a problem. I think these problems have to do with the rotary engine in general. Once you have a good cooling system such as a dual pass radiator, and dual oil cooler system that is properly ducted, cooling concerns are generly focused on the brakes. So in the past few years my car has become a nice track car by process of problem ellimination.
Now i'm moving up to a possible big brake kit due to the inability to run more than a few hard laps without the brakes getting a little spongy, and although the pads bite I Think i'm borderline boiling the fluid in the caliper.

TrentO

Hey Dan, try heat sheilding on the passenger brake line where it runs past the turbo and down pipe. We put an FC into the wall last year. After a decent session when he went out on track again , tried the brakes and had nothing. The passenger side line gets heat soaked by the turbo and boils the fluid. I have a stainless sheild around the turbo, a heat blanket on top of that and then some slide over heat sheild on the line itself. I'm also going to try a slightly thicker stainless backing plate between the brake pad and the pistons in the caliper, see if I can't keep the heat away better.

cheers,
-Trent

Dan Unk

iTrader: (7)

Hey trent, great advice, and I've got the gotham Racing turbo blanket and I also wraped the brake line in a double layer of thermotech tape I think the heat i'm dealing with is from the brakes themselves, the reason i think that is because i used a thick layer of that stop squeel red goo, and after one track weekend i inspected my brakes and that stop squeel goo looked as if had been removed with an open flame. I need a kickass brake duct system, what i have isn't cutting it, i've read a couple threads and i think i'll be going with the AWR rotor backing plates like Rocklobster has in one of his threads.

Let me know how the thicker backing plate works, i'm very interested.

Gene

iTrader: (1)

Dan, what brake fluid are you running?

Dan Unk

iTrader: (7)

Fresh ATE Super Blue. I change it every year. I really think it has to due with the brakes having no cooling ducts, i think the rotors are glazing over after a few hard laps. I'm going after a setof AWR brake back plates that have the opening for hoses.

Gene

iTrader: (1)

I was looking at those plates, but I figure I can make my own for a lot less money. A friend of mine was running ATE in his 911 and kept boiling it, he bumped up to Motul 600 and his problems went away until he started driving even faster thanks to his newfound confidence and had to install ducts. I've been running Motul in my FC for years and haven't boiled it yet. Motul's boiling point it 594 dry and 421 wet, versus 536 dry and 388 wet for the super blue, which is a pretty significant difference. How many events a year do you run? Changing once a year might not be enough.

If you're feeling spendy you can even use Castrol SRF with its 590 dry and 518 wet, but it costs $Texas...

bean13

iTrader: (1)

My personal experience is that the rules are set up in most organizations, SCCA, MC, IMSA, that turbo cars are behind the others. If it is hot out, and this is ussualy the case, the NA cars make more power. However, on cold or rainy days, you are the man.

I no longer race a turbo car for IT. Turned it to and EP car before I sold it.