North American Turbocoupe Organization



can the IHI do better than this or do i just need a T3?
kunar Offline
Member
#1
quite simply, im not too impressed with my stock turbo. i feel like something else is still wrong, but maybe im just expecting too much from it. let me know what you think.

the car is a mostly stock 87 t/c. im still running the stock top mount and stock ihi. intake is a stock upper. exhaust manifold is a ported e6. im running stinger's 3" down pipe and a home made 3" midpipe running back to the stock (ish?) 2" dual. cheap ebay boost control valve in place of the stock solenoid. in first gear, it will only boost to about 15 psi, 16 in 2nd or 3rd, 17 in 4th and 18 in 5th if im lucky. sometimes it will trigger the overboost buzzer in 5th, but just barely. its gotta be at 2600-2800 rpm before it will get to 15-17 lbs of boost in any gear. i unplugged my boost controller today just to be sure and it does the same exact thing. im under the impression that i should be able to build boost quicker and top out just a little higher (18 in all gears would be nice) so am i expecting too much or is something else going wrong?
1987 Turbo Coupe
1987 Ranger 4.0, 4x4
1991 Escort GT
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natmac3 Offline
Administrator
#2
Full boost (~15psi factory) at under 3k rpm is normal.

If you can't go past that, even with the wastegate reference line disconnected, then something's wrong.
1987tc
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Pete D Offline
Administrator
#3
The 2" stock exhaust isn't helping any. The more you open it up the quicker the boost and full boost.

It's normal to make a little more boost in the higher gears because the engine is loaded more than in 1st or 2nd.

With an IHI going beyond 18-19 isn't productive and is beyond the design limits of the turbo.

What is your ignition timing set at?
Pete Dunham


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kunar Offline
Member
#4
i was shooting for 18psi in all gears. timing is set at stock, 10* base iirc. i know the stock 2" dual isnt ideal but it was a lot cheaper than doing a full exhaust. i figure it will hold me over till i can save up a little more. it is 3" all the way to the split though. im contemplating on the t3, im afraid it will lag too much, i just hope it makes up for it on the top end.
1987 Turbo Coupe
1987 Ranger 4.0, 4x4
1991 Escort GT
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Pete D Offline
Administrator
#5
Try 12-13* timing for a small uptick in performance.
A T3 will definitely make more top end. Using one with a .48 A/R hot side will help minimize lag.
Pete Dunham


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