i was wondering if its typical for a b16 with a t3/t4 turbo to not reach full boost until 6500 rpm? im tuned and everything but just find it weird that it takes so long to hit full boost since my friends gsr is at full boost by 4000 rpm with a t3/t4 .60 trim turbo. i realize the gsr has more displacement but the fact that he can go full throttle and at least build some boost regardless of gear and i dont build any boost until about 4000 rpm just kinda makes me wonder if something is wrong or what. any input would be appreciated i have searched but havent found any definite answers

 

intercooler piping leak maybe..

 

well i can check again but wouldnt that cause me not to hold boost steadily?

 

No. but the tune could be also be fat (too rich) too low in the powerband. The T3/T4 you have could be too big for the b16 (Just having .60A/R doesn't mean anything. SC61s can fit in that housing). There could also be leak issues like mentioned before.

There's a lot for you to have to tackle here.

 

When my b16 was boosted, I was at full boost around 4300rpms, that's with a t3/t4 50trim.

 

well thats true im not exactly sure exact size the turbo is since i bought it used and it doesnt have any numbers on the housing. well the turbo never really spooled well from when it was first installed to when it was tuned and looking at the dyno sheet it shows my afr is actually kind of lean at idle (around 13) then goes down to 12 further into the rpm's. i guess i will check for any leaks in the piping, any ideas on any leak tests?

 

Just pressurize the inlet on the turbo and check the whole system at once. It would have to be a pretty giant turbo to spool that late, even on a b16.

 

ok i'll try that tomorrow, the turbo is a pretty decent size, well at least the housing is anyways i was just looking at my friends ebay t3/t4 .50 trim and it looks decently larger but i know the housings dont matter in regards to the compressor wheel sizes.

 

Ignition timing will play a big part in spooling a turbo up also. If there is little to no timing before boost it will take a while to spool. BTW I wouldn't say 13's at idle is running lean at all. Most cars should be able to idle and drive around at part throttle in the 14's. It shouldn't dip into the 12's until you get a load on the motor.

 

I would check for the leak first and then check timing next . . . just trying to give some options that i would try ... does definitly sound werd

 

need more info...what manifold, wastegate, ( internal or external ), pipe size, intercooler size... maybe a bad match up of parts.... just my 2 cents...

 

 

How old is the turbo? I myself would remove the inlet side of the turbo and spin the compressor wheel and check for binding and excessive axial play. Hope this helps.

Bret

 

oh really? because i was at stan from fasturbo's shop a few weeks ago talking to him and we were talking about afr's and he said it should never go above 12, but then again i guess he meant at WOT. but i dont know im not a tuner or anything i can upload my dyno sheet if need be so you can see the afr's throughout the rpm range.

 

its a meutek manifold, tial 38mm external wastegate, piping is between 2" and 2.5", and the intercooler isn't a ridiculous size either i dont remember exactly 24" wide and not very tall, i didnt have to do any cutting of the bumper or anything.

 

i had the turbo rebuilt at majestic turbo before i installed it and i checked it recently and doesnt have any shaft play still.

 

and i guess that would explain my terrible gas mileage too, when my car was boosted before tuning it got 29mpg and got 32 or more n/a. now i get 24 if im lucky which really sucks since its a daily driver. im thinking i may need to get a retune done somewhere else amongst other things.

 

Your manifold choice can also play a significant role in increasing lag. For example, i ran a setup with a topmount and subsequently switched to an SLS shorty. In doing so, i picked up ~50whp/50wtq and about 1100 rpm in spool. I would post the picture, but Photobucket is giving me errors atm...i'll try get it on here later

 

ah i see, i have a meutek log manifold and i've looked at the reviews on it and havent seen anyone complain about lag issues. i'll check later to see if you got the picture uploaded

 

Could also be your wastegate bleeding pressure prematurely... is there a boost controller involved or is it spring pressure only?

 

its on spring only, i havent had any luck with manual boost controllers holding boost they always tend to overboost for me. before it was only boosting to 4lbs with a 6 lb spring but we got that fixed.