Supra Question.

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I was wondering...how high can i boost my turbo on the stock twin turbos on my supra? right now i boost at 9-10 PSi..

94' Supra Twin Turbo

posted by  soljahx

dude if it stock turbos that means they're seqentional if so ditch that set up and go for 2 turbos the same size or one huge turbo and then up the boost the 2jz can handle it.

posted by  GreekWarrior

buying 2 turbos of the same size is nuthin cheap, so just ignore that WONDERFULL idea the other guy just gave.....

anyhow, its true, a single turbo set up is much better and far more efficient (my mechanic has one on his 2jz corolla).

but as for the stock boost the 2jz can handle efficiently with the stockers, from 12-15psi.

posted by  Inygknok

Hey don't underestimate the power the 2jz can handle.

posted by  GreekWarrior

dont speak supra with inygknok.... you'll lose.

posted by  jzxTT

lol yea.

i would be the last person in history to ever understimate the power of a supra, im obsessed with them and i own an older model (look at sig). i sometimes even get in over my head with them :laughing:

posted by  Inygknok

Could you explain why a single turbo is better and more efficient? I thought twin turbo reduces turbo lag so therefor better than a single turbo. ?

posted by  zipper

actually, twins dont reduce turbo lag. also there are 2 types of twin turbos, REAL twin turbos, and SEQUENTIAL twin turbos.

the "real" twin turbos, aka full-time twin turbos, is that both turbos are spooled up at the same time. the advantage of this is that both turbos will be giving u power all the time. the disadvantage is that if u know that turbos work on exhaust gases, well, instead of having the pressure of all the exhaust gases powering just one turbo, u have to use half and half, so spool time aint that great.

sequential twin turbos work differently. mostly, its one small turbo and one bigger turbo working. the key difference is that the smaller turbo will be the one doing all the work at a certain RPM level, and then the bigger one kicks in. ill sure the MK4 Supra as an example. all the way up until 3,000RPM, the small turbo will be the only one giving the car power, and then once 3,000rpms has been reached, the big turbo will kick in cuz the exhaust gas pressure is strong enough to spool it up fast, so in other words, the small turbo spools up the bigger turbo. the disadvantage is that, well, u dont have both turbos working full time, so one of them is just dead weight when they are not operational.


this is where single turbo set ups come in. while a single turbo will have the initial turbo lag of a full-time twin turbo (though the smaller the turbo is, the less lag it will have, get a really small one and u will barely notice the lag). turbos are efficient as long as they can work correctly with the torque band of the car. this means, that it can keep giving nice boost all the way up to the peak torque of the car. remember, torque is turning force (by definition). a single turbo will always be operational, and if u have the money, u can even get a lightweight one to save even more on weight. one bigger decent turbo can outlast 2 smaller ones due to the rotational speeds of the turbine blades (the bigger they are, the less rpms they have to go about in order to create the same amount of power).

full-time twin turbo cars are just the answer to big single turbos, but they are of no advantage just cuz they pretty much require the same force to spool up as just one big turbo, but they have more weight on them so no big deal (double the equipment is needed to run double the crap). then as for sequentials, well, just read the dead weight part above. single turbos dont have any dead weight since they are always in use.

posted by  Inygknok

Well, twin turbocharging is usually used to reduce lag. Just as you described as sequential twin-turbos, some engines use two turbochargers of different sizes. The smaller one spins up to speed very quickly, reducing lag, while the bigger one takes over at higher engine speeds to provide more boost.

posted by  What

imagine this.... imagine that u have just one small turbo.... its still gonna lag, but since the entire engine powers it, its ok. now just imagine u have 2 of those small turbos.... they dont have the entire engine powering them, no sir. u only have half and half (if the set up is that of a full-time twin turbo).

full-time twin turbos are not used to reduce lag, but just to produce some extra "easy" power by just using double the equipment.

posted by  Inygknok

Super chargers are the way for me.Superchargers afford the engine immediate response since the supercharger is always compressing intake air,
Where as the turbocharger spool up because its not immidately compressing the air, getting an what we call turbo lag at low engine speeds.

There are 3 types of super charger (i think :ohcrap: )
Root Blowers - (not recommended unless ya wanna cook chicken in there) It gets HOT
Twin-Screw Superchargers
Centrifugal Superchargers

Superchargers have a lot less Boost level than a turbo charger.
Reliablity wise Twin screw superchargers are the tops!

posted by  Lukaz

yeah but am i right in thinking s/chargers dont give anywhere near the same psi as turbos because they come in so early? instant power but drops off way to soon! I know the levin bzg i had was great for pick up, but levelled off real early. I'm a fan of the old 2-stroke engines in my bikes and love the powerband effect. i'm sure thats part of the reason i'm so into the turbos!

but plz anyone educate me on the supercharger and why I should be more open to its advantages over the turbo!

as for sequential, the vr-4 galant (not 3000gt) I'm getting is! and it feels great to me!!! the subaru legacy my wife has (twin turbo) is crapolla!! 2 stage which dont work well at all! even subaru have gone back to single turbos in the legacy now. it was the twin that runs both at once, one spools up first for a little bit of boost, then the second one kicks in at 5000rpm and gives it a bit more! and that lags BIG TIME!!! you cant fit an atmosphere blow off valve either (to minimise the blow back) as the engine dont have no mapping behind the air flow meter, so ping goes the engine if you do!

and there ends the rant of unlicensed! :clap:

posted by  Unlicensed

www.howstuffworks.com >>>>>auto stuff>>>>>>Car engines>>>>>how superchargers work. :thumbs:

posted by  jzxTT

only roots type SC's give u instant boost. centrifugals are just like a turbo run by a belt, and its exactly that. centrifugals will give u more power at the start, but it is proven that a turbo can actually give u more power starting from the mid-range and all the way to the top, and its only in the lower gears. once u reach the last half of second gear, n sometimes the beginning of 3rd gear, u wont see anymore lag, depending on teh size of the turbo ofc. some barely even see any lag starting in second.

posted by  Inygknok

I have a question dealing with the whole TT deal. My roommate just bought a TT stealth. We've been noticing that when he gets into the boost heavily, around 4,000 rpm we feel a slight hesitation in the acceleration. it's quite prominent in first and second gear but not so much in the upper gears. initially, we thought it might be the tires slipping, but after listening closely, we could hear that they weren't slipping. my thoughts were that the car has a sequential setup and we were feeling the bigger turbo kick in and start to provide boost.

does this sound like a plausible explanation?

ps, sorry if i'm reviving an old thread here, i just did a google search on sequential turbos and came to this thread.

Thanks for your help.

posted by  s_racer2003

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