boostedzxtt

I know that it kinda too big for the track, but it's tempting because of an awesome deal I can get on one. Does anyone use a T78 that road races here? Did you have any success, or would you just go a little smaller?

JHew84

iTrader: (9)

i'm sure there is a couple and you could get away with it, but like you've already addressed it's not ideal. If you are serious about racing and want to set the car up for a road course i'd hold out, there are usually affordably priced turbos that are much better suited for road racing.

Damien is actually selling is rb85 kit right now, if I didn't already have most of my single kit sitting in my office i'd probably buy it from him.

boostedzxtt

well, I'm not really that serious about road racing, I just know it would be really fun. I think I decided "Go big or Go home" I'm just gonna do it and have fun on the highways haha. But I'll still take it to the track and see if I can get some good lap times still. I'll post when I'm closer to the setup.

iceman4357

iTrader: (2)

im going to be going to the track. Just have to keep the revs high

j9fd3s

iTrader: (3)

if you're under 4000rpms anyways, something is wrong

boostedzxtt

So, why do people believe larger turbos aren't optimal for the track? I have always thought this too but never really questioned it untill now. It shouldn't be a problem for a larger turbo if you staying in high revs. On a side note does anyone know what kind of specs (engine) RX7s run in JGTC GT500 class? I'd really like to know that.

dradon03

iTrader: (2)

No Rx-7's run in the JGTC Gt500 class. Only Amemiya's Rx-7 in the GT300 class and he runs a 3-Rotor N/A.

Wargasm

I don't road race much, but here's my 2 cents.

Big turbos are going to run cooler at the same power level which is good for the "go big or go home" people.

Big turbos on a long track will be able to stay in the power range (5000+ rpm) which will lessen the 'lag factor'. If you were on an autocross, you'd be screwed with a big turbo.

Small turbos (in my opinion) are easier to modulate around a turn. Picture that you enter a turn at 60 mph, and you want to roll on the throttle so that you exit at 75 mph.... if your turbo lags a lot, you end up having to factor this in very carefully. You may find that you must go WOT "early" so that it spools and gives you the right amount of power as you approach exit. If this power hits hard and fast after a 2 second lag, this might catch you off guard and make the car harder to drive. A small turbo (or even a very small one) will not have a long lag time and so may be easier to modulate through corners.

Just my 2 cents.

boostedzxtt

Well, that explains why I couldn't find any in the past two hours of searching the web. LOL. I wonder why no RX7s are used in the GT500? If they were, in your opinion what would be a good setup to race the NSXs, Supras, Skylines? I know I am not building a full blow JGTC racecar, but I'm just curious what they run. What size turbos are on most of these JGTC Racecars in the GT500? I can't find specific specs on ANY OF THE RACECARS. I guess it is kind of a secret that they don't want competitors to know.

Nuvolari

iTrader: (4)

I think Fritz Flynn drives a t78 FD road car. No WOT when the wheels arent straight

I havent had my FD on a road corse but on the streets with the t78, it reminds me of a old 930 turbo. Brake early and dont panic when the *** kicks out.

boostedzxtt

I don't follow??? I'm not familiar with Porches I guess.

j9fd3s

iTrader: (3)

turbo response is like a light switch, under 3999 rpms, theres no power at all, 4001rpms its got like 300hp...

JHew84

iTrader: (9)

Was going to be my next point. A larger turbo with more lag will be a lot harder to control in certain situations. When road racing you want a nice smooth power curve, not nothing then a big burst of power. A bigger turbo will hit harder when it spools which can easily cause instability in many situations, and overall just be more of a handful around the track.

And also comparing the turbo's other JGTC cars are using isn't really useful when applying that knowledge to an FD, those are different cars, with different needs.

It sounds like your just looking for a cheap single setup, my advice would be get what you want since there really isn't any "specific" use you are looking to get out of it. Me, I intend to spend the majority of my time behind the wheel on a road course/auto-x track, so I went with a GT35R setup. It is in my mind one of the better matched turbos for that use, and will be plenty fun on the street.

ptrhahn

iTrader: (9)

Some of the better track RX7's out there have had T-78's, like Brad Barber's (Fritz's) Killer Bee, and Paul Winters car.. but that's perhaps because they were built when the T-78 was the best thing going.

GoodfellaFD3S

iTrader: (213)

I've seen Steve Kan storm around VIR with his drag car when it had a T-78 sized turbo, and he seemed to be doing just fine

boostedzxtt

I'm sorry, but what/where is VIR? And he was using his drag car on a road track?

JHew84

iTrader: (9)

I never said a large turbo like the T-78 couldn't be used successfully on a race car, just that it could easily prove to be more difficult. In road racing/autox the more ideal setup is a nice smooth powerband and the T-78 is usually described as a kick in the pants .

Also just because a few people were successful still is not enough evidence in my opinion. There are many factors that go into a successful car one of which being driver, another being conditions, another being the track. Someone who can adapt to the power curve of a bigger turbo and somehow figure out how to use it to their advantage could be very potent behind the wheel.

JHew84

iTrader: (9)

VIR = Virginia International Raceway (i'm assuming, correct me if i'm wrong rich). That track (depending on the layout that day) has a good deal of straight aways and long sweepers, VERY ideal for a high revving high powered vehicle.

rx7tt95

Paul's the cocky old guy right? He does pretty well with a completely track-biased car setup and a T78. I'm not convinced it's the ideal setup but he seems to like it well enough. The CHRA is oil-only which can be seen as both a benefit and a liability when road racing.

GoodfellaFD3S

iTrader: (213)

Nice descriptor

iceman4357

iTrader: (2)

I like my kick in the pants plus i think that your going to spend the most time above 4k rpm, unless you are going around a sharp turn, in which case you downshift. I cant wait to track my car this season.

JHew84

iTrader: (9)

Why is there so much obsession with spending so much time in the upper rpm's? As soon as you lift throttle you dump all your upper rpm boost and have to build it back up. Smaller turbos are more ideal, that doesn't mean you can't use a bigger turbo it just means that in most cases a smaller quicker spooling turbo will be better matched for that application.

I guess I don't have anything else to say, my opinions come from plenty of seat time at auto-x's and road courses, not to mention countless amounts of research on the topic before selecting my own single setup. Also from driving a few cars with improperly matched turbos and being disgusted with the lag, I would hate having to deal with that out on the track personally.

Jurgen

i drive a t88-33d for the road 500bhp its great you just got to learn how to drive it to achieve its power....


no such thing as lag if you can shift down once your in the power band and racing lag is outthe window lol

iceman4357

iTrader: (2)

I do not disagree with you, but we create the most HP at higher RPMs, and if you are racing, you would want the best part of your powerband to come out of a turn, so for a larger turbo 7 downshifting is ideal. Plus even with your smaller turbo your not going to generate your max HP at 2k rpm.

JHew84

iTrader: (9)

It still takes longer, downshifting or not, to spool a bigger turbo. That in itself is something you need to get used to and in certain situations can shave precious time off your laps. You can adapt to it and use it to your advantage in some cases, but as i've maintained they will work, it is just not the most ideal setup overall. With a smaller turbo the power is just there right away for you to do what you want with it, just because you have a smaller turbo certainly does not mean you wouldn't downshift coming out of a corner, you would and your turbo would respond quicker once your into that lower gear.

ask anyone who has had someone riding their *** through some esses, if you downshift to pull out of a corner and the power isn't RIGHT there that second the person on your *** will easily pull up next to you and probably pass. This is something that is more prominent on tighter road courses and auto-xing but you don't always need a ****-ton of power all the time, I was plenty competitive with my far underpowered protege' against WRX's and SRT-4's, without even really pushing it.