what is the max boost the mkiii can attain w/o having to upgrade fuel pump, injectors, and MAF?
Stock CT, consensus is about 14psi. Id say 17-18 with a CT upgrade.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.
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.what is the max boost the mkiii can attain w/o having to upgrade fuel pump, injectors, and MAF?
Ah, that’s right, 12psi. 14psi is what the turbo itself is good for if fuel cut is not an issue.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...
Well, I was close. If 375 is aggressive, than I wouldn’t shoot for any more than 350RWHP.Stock injectors are 440cc, so approx. (aggressive) 375 whp before inj upgrade is required.
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.
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.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?