hey guys...i was just wondering what the stock psi is set at for a ct26...ive heard its at 7, but then ive also read somewhere that its in the 5psi range. does anyone know for sure?

the stock wastegate is set at 7

This post has been edited by shin: Apr 4, 2007 - 10:18 AM

thanks alot

On the Celica/MR2 it's ~ 8PSI [sometimes a bit more]. 7 Is actually a bit low.

For the Supra it's ~ 5-6 PSI.

Also depends on your sea level. Mine was 8-8.5.

so, does this mean that if you put a CT-26 on a 5sfte set-up (the turbo will be coming from a mr2 or alltrac) and don't use any kind of boost controller that you'll boost 7-8 PSI?

No. Other variables control boost also, like exhaust for instance.

This post has been edited by Supersprynt: Apr 4, 2007 - 9:26 PM

Depends... my stock 93 mr2 ran 12psi stock....put a full exhaust on it and it will get up to 16psi in 4th-5th gear

This post has been edited by bufferdan: Apr 5, 2007 - 12:07 PM

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ct26 waste gate spring is set to 7psi.
on the 3sgte normal boost is around 10psi, because of the factory boost control (tvsv).

but if you get a bigger exhaust, youll have a harder time keep the boost that low.

so, if I use a boost controller will I be able to keep my boost lower than just depending on the stock wastegate?

honestly, I wouldn't mind boost 10-11 PSI, I just don't know how much my motor will be able to take and I want to take it as easy as possible on it for the first few weeks.

>

u cannot lower stock wastegate psi with a mbc. u can only raise it. to lower stock psi you would have to run an external wastegate and that can get pricey.

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If you got a mbc that works well, You could keep it at 5 psi. Thats very safe for that engine. 5 psi is how high it will boost when cold or when it sences a problem

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this is NOT true.
guys, this is simple.
the wastegate on the ct-26 opens @ ~7-8psi.
with a free fowing exhaust, it will creep.
a boost controller will only allow you to RAISE, not lower boost.

Exactly

And the TVSV can only raise boost from what the WG is set at.
It can't lower it.

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sorry,
I havent experimented with my mbc since it doesnt currently work. Ok, so if you use the tvsv and either turn it on or off, manually, then you would stay at 5 psi.

ok. I think I understand now. and I think I can scratch the MBC off the list of things I need for my 5sfte. at least for the time being.

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If your WG actuator is set for 8 PSI, you can't go below that, period.

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You CAN boost below 8 psi. when the tvis is activated it wont allow the car to boost past 5 psi. This is called SAFE mode. As ive heard it called. When the engine detects knock or cold temperature of the coolant temp.

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Your a little confused. its ok though. OK whatever the WG is set to is the lowest possible boost you can run.
when "safe mode" activates it turns off the stock boost controller TVSV and you run W/e the WG spring is.
when "safe mode" isn't on, normal driving conditions it bleeds off air so the actuator opens later, thus upping boost.
i suck at explaining things.

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trust me, jermey will know how the ct-26 actuator works better than you, hes a toyota tech. lol
besides the fact that he has one TATTOOED onto his arm!!
you have the right idea, just the wrong numbers.
on a 3sgte, in "safe mode" IS 7-8psi. when the TVSV energizes, it goes up to ~10-11.8psi.

sorry posted to wrong topic

This post has been edited by toyotacrazy: Apr 6, 2007 - 6:29 PM

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And has put so many CT26s on his alltrac than any one I've known.
Joking aside, the T-VSV is actually a bleed valve.
It bleeds pressure out of the actuator and let the wastegate open at higher psi.
It CANNOT make the car boost lower than the wastegate spring setting.

For a while I was swapping the damn things in my sleep.....

>
Actually you explained it perfectly.

Look, here's the deal.
I don't know EXACTLY what the WG actuator is set to.
It will differer between cars regardless.
Elevation, barometric pressure, humidity, age, wear and tear, heat, air temp, and production differences ALL will effect exactly when it opens. And how fast it opens.

The BGB states stock pressure is from 8 - 11.8 PSI. Most completely stock ones I've see are right around 8.
My 93 Alltrac NEVER ran 5. It was 100% stock [except for a boost gauge], and always topped out at 8 [give or take. Maybe it was 7.5 in actuality, or 8.5].
When I ran the WG vacuum line to the intake manifold it bumped to 10. And stayed there.
All the way to 173xxx miles.

Adding a larger exhaust, a DP, or an intake will raise the actual boost pressure without you using a BC.
So will a better ic. Cold air does this as well.
A buddy of mine has a 90 Alltrac. He put a full Aussie 3" exhaust, a ARC TMIC, and an intake.
He was hitting fuel cut without a BC.
He was rather unhappy with that.

Don't worry exactly what it's supposed to be.
As long as you are 8 - 12 stock you are fine.
12 won't blow your engine either. Assuming everything is good of course.
I had my 92 @ 14 for a long time [some 92/93 ECUs are set to ~14PSI fuel cut]. Part of it on a Supra CT26.
Never had problems. Stock ATA TMIC.

My wastegate must not be operating correctly. B/C during safe mode Im only hitting 5 psi. After it warms up Im only hitting 8-9. I see what you guys are telling me about the W/G being set at a specific boost and you cant go lower than that.

are you swapped with a stock exhaust?
if not, you have a problem somewhere, or your boost gauge is off.

>


X2
stock exhaust did that to me right after swap, I was not able to boost past 8.5psi. Once replaced, I have been able to boost up to 11psi all stock.

Don't forget, massively retarded timing, such as with a bad knock sensor, will lower boost as well.

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I thought the exhaust was slowing me down. I have a turbo xs dump pipe. Then I have about a 2.25" flex pipe. The rest is stock GT. I unbolted everything except the flex pipe. I still only boost between 8-9 max. If I put washers in between my wastegate actuator and the turbo, I can boost all the way to fuel cut (14 PSI). I wonder if my wastegate actuator is worn out. ????? Also, Ive noticed on the few nice 70* F days we had, my tvis monitor leds detected a problem. Then I could only boost to 5 psi. When I cycled the key, it went back to normal.

hmmmm, so much inconsistency, I just got a MBC because i got tired of 6psi(thats with 3in intake, Full exaust). Just yesterday i finally raised it to 9-10, pulls amazing, but i want to extract the most power possible.

My motor can more than handle it, it was rebuilt, with headwork and an 88MM bore(old was 87MM), the question is how much can I add with the stock engine management(ecu-fuel), and if I want more power what is something good to add?

*I'd like to add that the rotating assembly is fully balanced

This post has been edited by 95celgt: Apr 20, 2007 - 1:38 PM

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Manny, Jeremy and I probably have more than 20 years combined experience with CT26 and 3sgte.
Stock CT26 wastegate setting is 7 psi and with right condition and T-VSV fully functional, it will reach 10-11 psi without a boost controller.
If you don't believe that, here is what Toyota manual says


and my stock boost gauge reads 10 psi on a 92*F day
http://www.youtube.com/watch?v=REoG0k_LVjs

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You won't go very far with stock turbo and ECU.
Boosting more than 15 psi on a stock CT26 is pushing the limit.
You should consider a bigger/better turbo and other support mods (fuel, intercooling, exhaust, etc..)
Depending on your goal, there are different routes to do this.
300 whp or less, CT27/CT20B, reflashed ECU, 550cc inj, etc...
300-400 whp, TD06, T3/T4, SB kit, stand alone EMS, etc..

This post has been edited by Gary: Apr 20, 2007 - 2:01 PM