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1jz >
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Discussion Starter #1
what is the max boost the mkiii can attain w/o having to upgrade fuel pump, injectors, and MAF?

~Adrian
 

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1jz >
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Discussion Starter #2
also forgot to ask how much boost standard ct26, and ct26 upgraded to ct60 can handle with out over working the turbo.
 

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desufnoC
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Oni mkiv said:
also forgot to ask how much boost standard ct26, and ct26 upgraded to ct60 can handle with out over working the turbo.
Stock CT, consensus is about 14psi. Id say 17-18 with a CT upgrade.
what is the max boost the mkiii can attain w/o having to upgrade fuel pump, injectors, and MAF?
This question is a bit more tricky, it kinda depends on how much you want to push the stock fuel system. I think the question should be how much RWHP, not boost, because that’s relative to the size of the turbo.

Id say 380RWHP? Like I said, its a tougher question, hopefully someone else will elaborate.
 

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not to hijack but instead of starting another thread.
how much CFM does the stock ct26 flow?
 

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25psi Bliss
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~12psi more or less on the stock turbo depending on ambient conditions. Anything beyond this and you'll need some type of MAF / AFM, etc...

Stock injectors are 440cc, so approx. (aggressive) 375 whp before inj upgrade is required.
 

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desufnoC
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BlackDevilSupra said:
~12psi more or less on the stock turbo depending on ambient conditions. Anything beyond this and you'll need some type of MAF / AFM, etc...
Ah, that’s right, 12psi. 14psi is what the turbo itself is good for if fuel cut is not an issue.
Stock injectors are 440cc, so approx. (aggressive) 375 whp before inj upgrade is required.
Well, I was close. If 375 is aggressive, than I wouldn’t shoot for any more than 350RWHP.
 

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Here are some calculations I did in an earlier thread and they seem to do some good here too.

Here is the thread for refrence: http://www.supraforums.com/forum/showthread.php?s=&threadid=269294



Dirgle said:
It's a general rule of thumb the 1 HP pr cc so all thing being equal 440 cc injector should be able to produce 440 hp. Remember that this is crank hp not rwhp. And that would be at max flow rate aka 100% duty cycle and at 43.5 psi, not what our stock fuel systems produce, it is close though. Now if go buy the theoretical safe limit of 85% duty cycle(the point where you are guaranteed accurate spray patterns and long life of the injector) your looking at 374 bhp this is at 43.5 psi which again our stock systems do not flow at. The stock system fuel system at WOT is 33-40 PSI on a good pump. On a 14 year old pump…. If your lucky. So at 33-40 PSI (max stock pressure) our 440’s could produce between 284-343 bhp safely. Now remember this is on new injectors with accurate flow rates and a good fuel system. On a 14 year old car the flow rates have surly changed and the injectors aren’t as reliable. The engine came stock at 230 bhp, now well assume that was at 6 psi of boost(I think that is what it was, but I’m not sure, at the moment I can’t find the related material). Now lets take the theory that the ct-26 creates 11 rwhp or 13 bhp for every pound of boost. So using this theory, at 10 psi the engine produces 282 bhp and at 14 psi the engine produce 343 bhp. So……

On good 440cc fuel injectors
(minimum stock fuel pressure at WOT as per TSRM)
33psi fuel pressure can safely accommodate 10 psi of boost
(maximum stock fuel pressure at WOT as per TSRM)
40 psi fuel pressure can safely accommodate 14 psi of boost

Now you can see why Toyota put fuel cut where it is. Is there head room? Yes, a good amount of it too. The limits are there for safety, exceed them at you own risk. It may work for some and not for others. But now you know where your safe limits are.
Now these numbers of course are theoretical and will vary from person to person. But at least it gives you an idea.
 

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1jz >
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Discussion Starter #8
thank you everyone, that helps. so turbo is a good turbo then right? i can boost 12psi and not risk over working the stock turbo itself?
 

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desufnoC
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Oni mkiv said:
thank you everyone, that helps. so turbo is a good turbo then right? i can boost 12psi and not risk over working the stock turbo itself?
The stock turbo can run 12psi all day every day. It makes honest power to 14psi, some say more, but I dont know about for how long.
 

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hooligan
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I'm currently running 14psi on stock fuel system and stock turbo. Fuel cut is slipped the extra couple psi by means of a SAFCII. I still don't know what my car will do, when I dyno'd it the clutch started slipping at ~3800rpm, but was putting out 235hp and 305ft/lbs at that point.

lunsford managed 420hp on stock injectors if I'm not mistaken, though I think that's definately pushing the limits, and if I recall that was with a new pump and afpr.

The turbo starts to exceed efficiency around 1 bar, though there are a few people here who have run it above that. I hear they don't last long at 18psi.
 

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I run anywhere from 15 to 18 psi on the stock turbo right now because im not worrying bout fuckin it up cause the sp61 will be here soon. Just thought i would comment.
 

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1jz >
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Discussion Starter #12
hahah ok good deal. i think im gonnashoot for 12psi real soon then. if 12psi is safe for daily use. thanks guys

~Adrian
 
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