FEOA Forums banner

1 - 12 of 12 Posts

·
Registered
Joined
·
2,188 Posts
with enough $$ anything is possible... but there's no good reason to go to all the trouble with a 4 cylinder.

I know, I know.. Subaru uses a bi-turbo setup (two differently sized turbos, one for low rev and quick spool, and one for high rev high boost power) on their EJ20 in the Legacy B4, but if you read any of the road tests of that car you'll see that the powerband is disapointing. Powerful.. sure, but there's a flat spot in the powerband where one turbo is running out of boost while the other is still spooling.

As for a twin turbo.. (two turbos, of the same size), there's really no reason when there are plenty of modern turbos that spool fast and make boost all the way to the top.
 

·
Registered
Joined
·
8,915 Posts
if you can find a way to stuff two turbos between the radiator and engine block itself I say go for it. The emphasis on a TT setup is low torque and high end hp. the Legacy B4 (which I believe uses the EJ25, not the EJ20...only used in the WRX I thought?) is a heavy car, it needs the low end grunt to get off the line. WRX STi. 300 hp off the EJ25. not sure the boost level on the STi but the WRX already pushes 14 psi to get 227 hp. but neither car have horrible turbo lag. (so I've heard)
 

·
Registered
Joined
·
2,188 Posts
Nahh.. B4 uses an EJ20, only a 2.0L, which is part of the reason for the bi-turbo setup.

It wouldn't be hard to fit twin turbos.. there's plenty of room left to right.. and the turbos would be smaller in diameter than a single turbo, so block to radiator fitment shouldn't be a problem. The thing is, a twin turbo system isn't going to net you much of an improvement... Sure, the turbos are smaller and should therefore spool faster, but you're only using half of the exhaust energy to spool each of them.
 

·
Registered
Joined
·
1,204 Posts
yeah this has been brought up before. You really hurt yourself going twin. If you set it up to use two exhuast ports per turbo you cut your power to the turbo in half. so that right there limits your turbo size to something smaller. Now if you could set it up for the smaller turbo to use all four ports... boost and spool the bigger turbo you are onto something. however then you have to figure out how to have the exhaust/incoming air bypass the smaller turbo because once the bigger one kicks in the small one is just going to be blocking it. Its not an easy setup and there is no real reason for it anyway. The standerd escort turbo setup will get you spinning tires in damn near any gear. Going bigger will increase HP for crazy speed but that won't be real usable on the street.
 

·
Registered
Joined
·
710 Posts
I was at the shop having my resonator installed when I overheard the mechanics and shop owner going at it over a 3rd gen TT RX7. They said they'd never gotten one fixed right. The vacuum lines keep blowing off, the computer doesn't output the right trouble codes, hard to work on due to not having any room. The RX7 has a sequential system, small turbo spools first for low rpm and then switches over to the larger unit for high end. But it's a mess to look at and even worse to fix.
 

·
Registered
Joined
·
911 Posts
subaru legacy
s didnt come w/ a 2 turbo system. My friend andy has 2 turbo legacy's and a non turbo. The legacy has 2 heads, but not 2 turbos.
 

·
Registered
Joined
·
750 Posts
ok, now this has absolutely nothing to do with escorts, my uncle has a Turbo Trans Am, the V6 pace car edition, sweet ass car, hes upgraded the turbo, and now he has HORRIBLE turbo lag, his last 1/4 mile run was 17.927 @ 117.90, that some horrible lag, his turbo is hooking up top end, not bottom, so were working on a way to hook up TT, leave his big one, and then put his stock one on. The stock one would spool up faster, and by time the stock buries itself and becomed useless, the big one will finish it off, if not blowing the engine first,
 

·
Registered
Joined
·
8,915 Posts
Well, there's a difference between the large displacement V6 V8 models and I4 cars. V6s and V8s usually tend to have the torque to get them off the line at the low rpms, I4s don't, which is why supercharging is better for the larger engines. instant boost.

Since small displacement cars usually have to wind out to insane rpms to make any sort of horsepower, the emphasis is natually on the high end, making turbocharging basically the best option.
Turboing a high displacement car is, as your uncle found out, counterproductive. (for the most part) Especially if you take the stock turbo out and put in a turbo that emphasises on high end hp rather than low end torque.
It's funny though. He's got a Turbo V6 Trans Am pace car that my naturally aspirated 1.8 can beat out. :lol: 8O
 

·
Registered
Joined
·
2,188 Posts
92gt5spd said:
subaru legacy
s didnt come w/ a 2 turbo system. My friend andy has 2 turbo legacy's and a non turbo. The legacy has 2 heads, but not 2 turbos.
Correction.. Subaru Legacys didn't come w/ a 2 turbo system in North America. That's why I specified the B4 Legacy.. I don't suppose your friend has one of those :wink:



Supercharging is great for making a 4 cylinder more driveable.. ups the power all the way across, making for a torquey 6 cylinder feel.

I'm suprised that the Trans Am would only have one turbo, considering most multiple banked engines (V6, V8, V10, V12.. etc) have turbos on each side.

Your uncle may want to look into nitrous to get him off the line.. the turbos will spool in no time once the nitrous hits... Otherwise, he may want to work on his launch technique.. big turbos work great at the drag strip.. they just take a lot of practice.
 
1 - 12 of 12 Posts
Top