6G Celicas Forums

how many lbs of boost can a stock 5s head handle....im not worried abt. the internals just the actual head.

c. this question is impossible to answer

200 psi
Seriously, You might outflow the F head but it is not gonna blow because of boost.
Head gasket is another story.

i thought u could crack the head w/ too much boost so i wasnt sure if ne1 has ever done it b4...do yall know how much stock pistons can handle...

to many unkown factors to answer that question accurately.
psi is a very vague measurement of how much pressure the engine isn't ingesting. and not to much is known about the limits of the 5fste except it can handle a good beating.

why do you ask ?

how much power do you want to make ?

the more the boost the more the bottom end will hate you ... the head will be fine ... the "head" is more affected by raising rpm limits than it is by having boost in it...

the thing is say you want to make 300hp out of a 5sfe... it will take ALOT of boost on the stock head.... if you cam it , or oversize the valves, or port it properly it will take less psi to make the same hp figure... that's really how the head comes into the equation...

o...well do u think stock pistons can handle 15psi? not daily but i dont want to build a motor w/ stock pistons thinkin it can hanle the power and not...thats all i was wonderin....basically wat do i need for 15 safely? maybe thats a better way of putting it.

on what turbo? 15psi on a ct26 like i have, and 15psi on the holset that itchy has are two very different things.

the problem with running high boost on a 5sfe is not with the strength of the pistons or the head. its with the fact that its a high compression motor. the higher the compression, the more chance you have to run into detonation when trying to turn up the boost on pump gas. detonation is what ends up killing pistons, rods, headgasket, etc...

Would water/alcohol injection resolve this? I've been reading up on the devil's own kit and am seriously considering it being that I already run 15 degrees timing and I'd like to run more but I get pinging from 91 octane, but If I went with DO's W/A I. the effective octane would be 110+....

so low compression pistons wouldnt b a bad way to start? Im trying to find a ct26 now...is there a diff. between the mr2 one and the supra one? cuz i think i might b able to buy the supra one for like 50 bucks practically new.?

Low compression would be a good start if you wanted to build the engine.
since your talking about dropping some money into the 5sfe id recommend just swapping in a 3sgte and put the money into that.
the potential of the 5sfe isnt as great as the 3sgte, depending on how far you want to take it.

The supra ct26 has a different downpipe flange to it, you would have to custom make a downpipe to use it. also it flows a hair more on the exhaust side than the mr2 ct26, its also single entry where the mr2 ct26 is twin entry. The easiest route is to use the celica/mr2 ct26.

it wouldnt totally resolve it, but it sure would help a lot. for you, since your NA, using WI is going to be tricky, because its a system that is normally triggered by boost.

if your going to drop the compression on the 5sfe, you might as well just go with a 3sgte swap. youll get a low compression motor, with a turbo, injectors, and ecu that can handle 15psi on a ct26, just fine. it would probably cost you the same as your motor build up, and the sky is the limit if you want to make more power down the road.

for WI on an NA im pretty sure they use an rpm & wot trigger just like nitrous.

91 octane? y don't you run 93?

cali only gets 91. still, if your pinging on 91, then its probably a good idea to back off the timing.

for the 3sgte swap its like 4000 and thats if u do the wrk urself....im not plannin on spendin that much...in the end ill prolly have put at the most 1/2 that. and have the same or more power....but it would only b 2 wheel drive.

its going to cost you more then 2grand to rebuild the motor, lower the compression, turbo it, and tune it.

idk...im gettin a lot of parts REALLY Cheap....yea...itll prolly cost a lil more but still not 4g's and by the time im done itll put down more power than the 3s...at a lower price...the only thing im "iffy" abt. is i kinda want the all wheel drive but....i still want the 5s motor tho....sooooo

you do realize that most 3s swaps are not awd, right?
what turbo are you planning to use?