Thread: BIG TURBO/Hardcore turbo guys. I want your opinion

Okay so like most people here ive moved up through the turbo ranks. I started with a T25 and loved it but got tired of it. Then moved up to a Greddy 18g and I absolutely love this turbo also. I actually havent gotten tired of it at all lol. But I want balls to the wall roll on power and a car that can crush at the track also. So Im moving to a bigger T3 Turbo. From what Ive read its at full spool at 4500rpms where as the greddy is making full spool at about 3600rpms. The greddy makes a great 1/4 mile turbo. But for high speed run ins with the big dogs im gonna need more then 400whp. Now onto the important stuff...the questions:

All you guys with big turbo setups, do you regret not going with something more responsive? I mean turbo lag sucks and all. But as long as the turbo spools before 5k then you still have boost through out all your revs as you go through the gears. So it cant really suck that bad. Daily driving I never get into boost anyway so that wouldnt really be a problem would it? Next question...

With these big turbos do you find that you actually have better traction? I mean the lag should be good enough to get traction well before boost. Put that with a long winded P11T tranny and I should have a car that has a nice long usable power band in each gear. At first I was thinking that I wouldnt want the G20 tranny because of the long gears. With a quick spooling turbo I guess it could hurt acceleration. But with a bigger turbo longer gears would be better.

Anybody have any comments here? To me turbo lag isnt a big deal when you get such a hard rush when the turbo does kick in. But its not for some people. Do you love or hate your bigger turbo?

wang wang my friend your on teh right track, dont worry at all about the lag, you will just spin less and you will have a monster 3rd and 4th gear i prefer holsets because i find they are more efficient compared to journal bearing garretts but if you have the money to get a ball bearing garrett turbo then do so you wont regret it at all

ps ve head brian crower valve springs and 9k rpm rev limit

T-

I don't regret it AT ALL. I love the sound and spool of the 30r. Tire spin like MAD though. Better get some really good street tires, or cheater slicks.

trade me your 18g & mani for a t28/gtir mani plus cash... do it!

Sometimes a better larger turbo can make more power and spool faster than a cheesy cheap smaller turbo. I.E. The GT28RS makes more power and spools faster than a lot of the T3/T4's out there.

If you go too big with a turbo then when you shift at say 8k rpm you will have a bit of lag before you get back into boost. A turbo that makes more power than a GT3076R but spools about the same is a GT3082R. Its a GT35R but with a 60mm turbine instead of the 68mm turbine.

You should also consider your cams, turbo manifold being important in spooling the turbo as well. a smaller diameter shorter runner turbo manifold with a larger turbo can make more power and spool faster than a turbo manifold that has the runners too large and too long with a smaller turbo.

So you're saying that with a larger turbo you should reduce the length of the exhaust mani runners(i.e. log manifold)?

not always the case. every setup needs to be tailored to the specific needs of what it is being built for. If i'm building a setup for all top end power, I may not worry too much about lag, but i do take transient responce time into account. All this does depend on the transmission gear ratios as well. If you are trying to get every last HP possible, I may try to go for a larger turbo and or turbine housing. If its for a drag setup or trying to just get from point a to b the fastest, I will try to make as much HP as possible everywhere for the top 40-45% of the power band with as little lag as possible. In this case, Having a motor that makes 400whp at 5000 rpm and 450whp at 7500rpm can be a lot faster than a motor with 300whp at 5500rpm but 500whp at 7500rpm.

when going for top speed where you will be WOT for more than 10-15 seconds at a time, the turbine housing size has a lot to do with even making this possible. You will be making a lot of heat with the motor and if you have a turbine housing thats too small, you will have too much backpressure and can have detonation problems and or melt a piston. Just a thought.

Some of these big turbos are not as laggy as most people think.I'd never go back to a much smaller turbo.
t25,t28,3071r,gt42.... im done.That will be enough power for me.

^^so your running a GT42??

Tokes, The turbo actually went up for sale a few days ago and is sale pending at this point along with my external wastegate stock manifold setup. Ill let you know if it falls through though. I honestly dont want to sell the turbo. But I have to to ge this new setup off the ground and running for the convention!

Ive had many different set up's. Go with a larger T2 turbo. Call it a day, you will make the same power as some larger turbos, you will make more TQ also and stay in boost way better.