Slow '90 supra turbo :( Bad turbo?

[DialTone]

Hi,

Have recently acquired a Mk3 Supra Turbo (7MGTE w/ CT26 turbo, no mods). Engine seems to run OK, no smoke, no overheat, 40psi oil pressure, but turbo boost only running 0.5-1 psi. Pickup is terrible (0-60 maybe 15ish seconds), and top-end of around 90mph [would this be normal if the turbo shaft was broken?]. Auto box seems to be kicking up/down OK though.

Firstly, anyone have any suggestions as to what I might want to look at first? Secondly, if the turbo itself is faulty, how easy are they to swap over? I've already checked the diagnostics - no errors, and removed the inlet hose and checked that the inlet rotor spins freely, no noticeable splits in hoses, but sounds like maybe it is venting pressure somewhere :S

TIA
Tony

[DialTone]

OK, I think the problem is solved now - apparently this was a problem with the front cat being totally damaged, and some leak at the exhaust manifold. Now boosts at around 4-6 on the stock gauge, and performance problem solved by removing the cat and reseating manifold.


Tony

[suprra_girl]

Hey Tony & welcome to the forum

glad you got your problem sorted.. happy boosting
what gauge have you got? are you talking bout the factory boost gauge?

i would think the first & best mod would be a boost gauge with vacuum... it will tell you straight away if you ever have any problems related to air
usually the reason exhaust manifolds leak is because of the manifold bolts, sometimes you may find that the threads in the head are stripped and the bolts refuse to tighten and just strip it out worse
but if yours tightened up sweet... then minta

have a supra day

[DialTone]

Hehe Thanks for that! Yeah, car is totally standard atm, so it is the stock gauge - will def look at getting an aftermarket one. Not sure if the manifold bolts were snapped etc, but if so, the place I took it to (Owen Developments) said they would have re-tapped and rebolted everything.

Anyway, drives sweet now, so just need to start saving for the fuel bill

Cheers
Tony

[suprra_girl]

well reason i get confused on stock gauges is i just found out that different countries have different measurements for their factory boost gauges

ohhhhh the confusion :blink: :lol:

nz ones read mmhg so i assumed all countries did... toyota.. of course haha

auto's generally boost lower than manuals so don't be worried if someone you know that has a 7mgte boosts more stock.. it's probly coz they're manual
i would get rid of that stock exhaust too.. major restriction, but check out your local emmisions rules first

first things first

boost ==== get more lol
exhaust
intake

then later on... get an upgraded ct26 done
if you've got the $$ when you get the exhaust done get rid of that elbow while you're at it and get a proper 3" elbow made and the 02 flange welded to the new elbow.. you'll sacrifice a little torque but at the end of the day there's more power

after that i would got for intercooler hardpipes & intercooler
if you're not 300whp or close enuf to then ya missed somethin hehe....

also before!!!!!! you do any of this make sure your head gasket is secured by a metal head gasket & arp head studs

happy supra boosting

how much boost does the c-t26 turbo produce?

how much does stock 1jz produce?

[suprra_girl]

try to keep new questions in new threads etc, it keeps the previous threads tidy and on topic for the original question

stock ct26 from the factory on a stock engine will produce anywhere between 4.5-7psi depending on if it's auto or manual

1jzgte boosts in stock form i believe 10psi from two turbos