kb58

The following is only my preception, I've never driven a turbo car on a road course.

If there are two identical cars, both with, oh, 220hp, and lets say identical weight. One makes it via NA, the other with a low pressure turbo. And before the arguing starts, lets say our two fictional cars are equally reliable. Oh and both have the same driver.

Okay, take both out on a road couse and run 50 laps... who has the faster lap time at the end of the day?

My gut says the NA will, due to (my perception) of better throttle control. When I'm mid-corner, in a slight four-wheel drift, throttle control is extremely important. Pushing on the gas pedal for >.< this much more power, will move the back end out >.< this much (in my RWD Mini.) But if two seconds later (as the turbo spins up) I get >...< this much more, the back end's going to come around on me. Having what amounts to a rubber band between the gas pedal and engine isn't a good thing on a road course, where fast lap times = riding the edge of adhesion.

Alright, that's my take on it, but I admit I just don't know. Who here has done trackdays in their turbo car? How did it handle mid-corner?

Todd Reid

hi kb!

you only forgot one thing; thats TORQUE. the low pressure turbo is gonna have a TON of torque at low rpms. gonna rip that car out of the corners and onto the straights.

turbo car will be quicker around the course, i think, given that it has sufficient traction, and good reliability as stated above.

later

PS i have a nice 2003 EVO that i street drive, and that thing has tons of tq that comes on between 3k and 3.5k. and its a mostly stock 2 liter engine!!!!

kb58

I understand, but my concern is mid-corner, where, when you push the gas pedal just a little, two seconds later this ton of torque turns the wheels to smoke and puts you off the road. It's that delay I'm concerned about.

I have a suspicion that turbo drivers actually go around corners slower than NA cars, to stay away from that "torque rush." They then make up what they lost in the straights... just my impression though.

Todd Reid

hi again.

i had the EVO out for "fun" for 4 track days in the last two years. i never dropped below about 4k rpm out there. didn't really experience any lag. very very easy to drive. very easy.

of course, that car is awd.

but, i believe, given a couple days to get used to it, that i could drive a fwd, properly set up turbo car really fast. just would take some good, smooth driving....

clemsonhatch

Twin-charge FTW! Lots of torque with no lag

Weston

The turbo will have more torque and a fatter powerband. It can also help make up some of the difference when additional load is placed on the engine (ie up hills, shifting short, etc). So, with the same peak HP and torque numbers, I would put my money on the turbo engine, assuming it's properly cooled (turbo heat soak sucks). As for throttle control, it's definately different from NA and is a skill that you'll have to learn, but it is quite controllable.

As I approach corner exit, I just give it a lot of gas to get the turbo going, and then immediately ease back on the throttle <u>before</u> the power hits. The key is anticipation, because if you just keep your foot in it and let it come, it's a pretty frustrating experience to try to modulate it, since it's very non-linear and on a slight delay too. It takes practice to get the timing and amount of throttle right, but it works really well and has become second nature for me. And this is with a small turbo that spools up really fast, which is harder to control, but awesome when you get it right. Some people left-foot brake to keep their turbo spooled up, but I find that I really don't need the extra heat in the brakes or the turbo.

rmcdaniels

Weston, can you post a pic of your torque curve? I pretty much had to do this
:

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by kb58 &raquo;</TD></TR><TR><TD CLASS="quote">I have a suspicion that turbo drivers actually go around corners slower than NA cars, to stay away from that "torque rush." They then make up what they lost in the straights... just my impression though.</TD></TR></TABLE>

But my setup had an insane torque ramp:




I've talked to Cody Loveland, and his turbo setup seemed very good for the track:



But his setup was just 7 PSI from a big turbo (GT35R), where mine was 20+ PSI from a GT28RS.

EMod Civic

When I was running a turbo on my Civic in Street Mod, I spent a lot of time working on the drivability, particularly the mid-corner part throttle aspects. With the turbo making 12psi, the car was very difficult to drive in corners - throttle response just wasn't linear. At 5-6psi it drove like an N/A motor. My solution was a simple two stage boost controller with a switch located below the throttle pedal. At part throttle, it opened the wastegate completely, resulting in around 5psi and good drivability. At full throttle with the switch engaged, it jumped up to 12psi and made crazy torque.

-Chris

STN_Pat

This must be sweet...

coneheadsracing

I realize rwd is different the fwd. First, a couple seconds of throttle, even full throttle which is more to make the turbo spool, wouldn't make much boost, unless your running a really small turbo. I have a single cam turbo in a hatch, 15 psi. I ran it at gratton three times this summer, and once at gingerman. I never had any problems with mid corner traction, that was on street tires. I have a .48 / .60 which is a fairly large turbo for that engine. You learn very quickly how to modulate your throttle and get out of a corner in a hurry. As for controling your drift, i don't see that being an issue, i just don't think your going to hit much boost, plus look at all the proffessional drifters, there all turbo'd. I say boost it, you will definelty be quicker out of the corner, then the NA car in your example, and in my opinion, you should have equal corner speeds.

WWDTrackRacer

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by kb58 &raquo;</TD></TR><TR><TD CLASS="quote">I understand, but my concern is mid-corner, where, when you push the gas pedal just a little, two seconds later this ton of torque turns the wheels to smoke and puts you off the road. It's that delay I'm concerned about.</TD></TR></TABLE>

Well turbo selection is going to determine its behavior. I think you can choose a broad range turbo and be very happy. If you pick a peaky turbo, you'll probably experience a lot of the issues you're worried about.

I never thought my MR2 Turbo was a handful because of the turbo mid corner. Of course, I never put on a peaky 400hp turbo.

Any car with big gobs of torque on tap will be a handful, turbo (lag) or not.

Def

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by WWDTrackRacer &raquo;</TD></TR><TR><TD CLASS="quote">

Any car with big gobs of torque on tap will be a handful, turbo (lag) or not.</TD></TR></TABLE>

Completely agree.

You guys are comparing low torque motors to high torque motors. If you aren't used to fine throttle control, then no matter how you get your power will be a problem. A very laggy turbo setup is another issue entirely, but looking at stuff like P2 prototypes in ALMS or late 80's F1 cars(that had pretty much no driver aids from our perspective), they obviously have a large amount of lag and seem to drive around just fine.

A moderately sized turbo making ~250-300whp on a ~1.8L engine is more than tractable enough from a lag standpoint, and only makes enough torque to a problem for those that just like to blindly stab the throttle.

turboteener

I was talking to a CART driver a couple of years ago about this. I ask him to compare driving a turbo car and an NA car. He said he could go just as fast with either car, he just had to "plan for the boost". His driving style was adjusted for the turbo.

Since most of my driving is oriented towards road racing having a laggy turbo setup is not my idea of a fast car. I am running a small T3 right now and find that it is just fast everywhere. It pulls like a freight train at any point. I can go hard into a corner and modulate the throttle to drive through it. I can feel the boost fall off when I easy out of the gas mid turn, but it seems to come back on when I need it. When I roll back into the throttle on corner exit, I am usually at enough RPM boost comes back on in a pretty linear fashion.

I wouldn't have a 220hp turbo motor, if you have the turbo use it to generate an even 300. That is a reliable drivable setup that spools quickly.

slammed_93_hatch

honestly are you ever going to be below 4 thousand rpms ???


Thats one thing to think about on a road course you are always in the high rpms, i relize you do have a h22 so it doesn't rev that much, but it still revs.

Outrun

I remember something about Champ Car drivers having to adjust their style to anticipate the turbo "coming on".

Parker Johnstone (former Honda Champ Car driver and Champ Car commentator) explained that even though Champ Cars have sequential shifters, the drivers would still blip the throttle during downshifts. Racers don't do this in normally aspirated race cars with sequential trannies. But in a Champ Car, the blip of the throttle is used to keep the turbo's RPM from dropping too low.

I've always wondered how a D16Z6 Civic with a Jackson Racing Super Charger would compare to another Civic with a GReddy turbocharger in terms of laptime and ontrack behaviour (all else being equal).

Bakeoff

I do auto-x, some events sponsored by an Austin-Healey group that sets up the course extremely tight. I also do some road course events. I'm running 14psi out of a t3/t04e on a d16z6. Mid corner is no problem. All you have to watch is throttle. Obviously it takes a few seconds to spool up 14psi. With small amounts of throttle you will only build 1-2 psi. Heck, you can get that with ITBs and a scoop at the right speed.
Now, adding in an LSD and traction bars tamed my car down a lot and made it gobs more predictable. But I have no problem in my del sol mid corner. It's smooth and predictable as long as you're not driving like a throttle happy 16 year old.
Again, properly sorted suspension will make or break any car mid corner. An LSD can certainly tame it as well. But really, that will affect any car.
I guess my point is that once you are truly driving the car, it doesn't matter if it's turbo or NA. It will respond to your inputs and you will have to adjust to the cars output. I know that I need to tip in on the throttle a hair earlier if I was off the gas and need to get back into it exiting a corner. Adjust and there will be no problems.

nonsense

What about option #3, Jackson Racing Supercharger? No turbo lag, always has boost. Less under-hood (uh rear engine compartment) temps.

SIred91

The SC'd car would crush the Turbo'd car, all other things equal......

RacerXI

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SIred91 &raquo;</TD></TR><TR><TD CLASS="quote">The SC'd car would crush the Turbo'd car, all other things equal......</TD></TR></TABLE>
That is absolutely incorrect.

rmcdaniels

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nonsense &raquo;</TD></TR><TR><TD CLASS="quote">What about option #3, Jackson Racing Supercharger? No turbo lag, always has boost. Less under-hood (uh rear engine compartment) temps.

</TD></TR></TABLE>


I'll post how my SC setup turns out, the pistons just came in last week and it should all be going together in the next month or so. 300+ WHP in an EG hatch with a flat torque curve should be interesting at the track.

Weston

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SIred91 &raquo;</TD></TR><TR><TD CLASS="quote">The SC'd car would crush the Turbo'd car, all other things equal......</TD></TR></TABLE>

Nope... not even close, especially when it's a JRSC.

Weston

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by rmcdaniels &raquo;</TD></TR><TR><TD CLASS="quote">Weston, can you post a pic of your torque curve?</TD></TR></TABLE>

Here is a somewhat old dyno, with the VAFC setup on 9 psi... it's a little fatter with slightly higher numbers now, but the shape is mostly the same.

turboteener

I'll be happy to put my turbocharged street car against a similar supercharged street car on the track. I will drive both cars to rule out driver differences or we can find someone that will do it for us.

I thoroughly believe I will walk all of any supercharged car.

rmcdaniels

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by turboteener &raquo;</TD></TR><TR><TD CLASS="quote">I'll be happy to put my turbocharged street car against a similar supercharged street car on the track. I will drive both cars to rule out driver differences or we can find someone that will do it for us.

I thoroughly believe I will walk all of any supercharged car.</TD></TR></TABLE>

Come to Road Atlanta for the BMW CCA event next year, I'll bring my JRSC'd Civic and we can compare lap times.

kb58

That would be a good comparision, but only if they have the same boost, tires, shocks, springs.... etc.