turbo choice

[MrChallenger360]

alright so i have a stock GS-T that I've been working on for a while. been driving it with the stock T25 and it pulls nicely. Then i got a good deal on a bullseye t04b v-trim with a nice header and decided to buy it. So i put it on there expecting the car to pull even harder and i am less than impressed. i know that the powerband is higher than the T25 but even when im in that band the spool is really slow.
Can anyone explain this to me? are there some other mods i have to do with this bigger turbo to get it to act more like the T25? if i can't figure something out it's coming back off.

Thanks
Brian

 

[tbonitz301]

I guess your just running wastegate pressure. You need to push more boost to wake it up. I thought the same thing about my 16g until i turned it up to 20psi.What a difference. Get a walbro 190,logger,afc,mbc,and some650's.Then you will probably be wanting a front mount

 

[delta448]

You need supporting mods for that. Simply adding a bigger turbo doesn't do anything except increase lag. If you want quicker spool, free up the exhaust path after the turbine. If you want more power, you'll need more fuel and a way to manage it safely while increasing boost pressure.

 

[turboboy4]

You should get a good 3" exhaust setup, 650's, either a 255 w/ rewire kit or 190 fuel pump, and your choice air/fuel control. SAFC and a pocketlogger should do fine. Then start turning up the boost

 

[MrChallenger360]

well i have a 3" catback system on it now. should i get a 3" downpipe and test pipe? will a 190 pump bolt up easily? i'm totally new at turbos so tuning could be an issue.

 

[romeen]

As the others said you need more fuel flow (pump, injectors, way to control) so that you can turn up the boost and start taking advantage of that turbo.

It is also a good idea to do a boost leak test after any sort of work like this as that can dramatically affect performance. Did you use new/good condition gaskets when you swapped turbos? Make sure you don't have any pre-turbo exhaust leaks.

One other thing to keep in mind. Perceived rate of acceleration can be deceptive. Quick spooling turbos can "feel" faster due to less lag and how rapidly the boost increases once the turbo has spooled. Midrange torque makes for a fun streetcar even though all that upper end air flow will make your car quicker in a 1/4 mile race.

 

[erald01]

Do some more searching on supporting mods for T04b turbo, there is plenty of info.

 

[red97tib]

http://www.vfaq.com/index-main.html Go here for a few good write-ups on installs and such. There is one for a Walbro fuel pump for your car. It explains in detail how to do the install with pictures included.

 

[cjridert1]

dont waste $$ on a testpipe - are you getting boost creep? What for psi are you running anyhow?

 

[tbonitz301]

Just so you know when you purchase a fuel pump go with a 190 walbro unless you want to spend the extra 150 on an afpr so you dont overun your stock regulator with the 255.

 

[92awddsm]

You are comparing apples and oranges. If you want spool like the t25 but more power, get a t28. Once you get into larger turbos, you sacrifice spool time for top end power. The v-trim has also been known to be a slow spooler. I had a v-trim at one time and I didnt keep it long just because of the disappointment factor.

 

[MrChallenger360]

dont waste $$ on a testpipe - are you getting boost creep? What for psi are you running anyhow?

boost creep? well generally unless i really lay into it im not getting any boost @ all. my gauge sits @ 0. it's internally gated and i'm not quite sure what actuator it has. if i really lay into it i can get 15lbs but it takes a long time to get there.
if i get a 3" downpipe it prob wont fit to my stock cat so i gotta figure out something for that.

 

[MrChallenger360]

You are comparing apples and oranges. If you want spool like the t25 but more power, get a t28. Once you get into larger turbos, you sacrifice spool time for top end power. The v-trim has also been known to be a slow spooler. I had a v-trim at one time and I didnt keep it long just because of the disappointment factor.

yeah, i really wanted to get a T28 but this v-trim was as much as i could afford. plus i've discovered they're harder to find than i thought. if anyone has one they wanna trade i'd do that.

 

[MrChallenger360]

does anyone think maybe i could add a SAFC that would take care of the upgrade for the fuel side? or would i still wanna go with injectors and fuel pump?

 

[red97tib]

You need the injectors and the fuel pump. The stock pump and injectors can't keep up with the demands of a bigger turbo.

 

[MrChallenger360]

well i found a set of 720cc and a SAFC would that be a good fit?
still looking for a downpipe and fuel pump. since i have 2.5" exhaust should i get a 2.5" downpipe or a 3"?

 

[romeen]

720's are a bit too big if using a SAFC. It may be possible but from what I understand it will make tuning very difficult.

 

[delta448]

If I were you I'd be looking at a keydiver chip, a 190lph pump, a cat-delete downpipe and some 650-750cc injectors. You can also make a rear O2 simulator for under $20 with parts from radio shack or any electronics store.

If you want to get more into tuning I'd recommend a WB O2, datalogger, a max size of 650cc injectors and the SAFC instead of the chip.