which spring for safe boost on ka?

[pacefarm]

what up everyone.

i'm working on the following set-up on my ka:

t3/t04e
255 walbro
555cc injectors
fmic
38mm tial wastegate (currently 5psi spring, gotta find out what spring to get)
blitz bov
apex'i safc
3" downpipe/3" one piece catback
z32 mafs

i know i'll get a million "you should" suggestions. what i'm looking for, is a safe boost level with the setup i have. i'm planning on tuning the car at a shop that's got a wideband and dyno, etc. what i gotta find out is whats a safe boost level i can run on the above set-up. which spring should i get for my wastegate? and with what hp would i be pushing then, approx?

thanks in advance!

[orion::S14]

Since you have no way to control timing, you need to keep it at less than ~250rwhp...or roughly 8psi.

You have plenty of fuel, a big enough MAF, etc...and you can knock the base timing back to ~16-17 BTDC to give enough retard to keep it safe-ish...but any more than 8-9psi WILL require more advanced timing control.

...

SO...stick with your 5psi spring, use an MBC to pump it up to 7-8psi...and leave it there until you get a tuned ECU.

- Brian

[pacefarm]

so its possible to raise boost via a boost controller, manual or electronic, even though i have a 5psi spring? sorry, dont know much yet about mbc/ebc's.. its a learning experience :)

thanks for the reply btw

[TheWolf]

Yes it's possible. infact that's what they do. Say you had a 10psi spring in there. No matter the boost controller that you use. You can not control boost under 10psi. What a boost controller does is limit when the wastegate see's >10psi of boost. Say you were using a greddy profec bspc2 that's setup for 15psi with the same wastegate spring. Without it the wastegate would open at 10psi but with it. The computer see's 14-15psi and tells the electronic solenoid to pulse alowing 15psi to reach the wastegate and open. It pulses because if the wastegate were to see 15psi for a while it would limit your boost back down to 10psi. A MBC does the same thing with a ball and spring valve setup. Say by turning it clock wise and rightening up the spring. You make it to where it takes 15psi to push the ball off the spring seat. So then the wastegate opens when 15psi is achieved instead of 10psi because it takes 15psi for the signal to reach the wastegate. Thus the problem with MBC's is that once the ball is off the seat it make take some time for it to reseat and thus your boost might fall off at high rpm or prolonged runs.

[pacefarm]

thats awesome, thanks for the very informative reply! [thumbsup]

so i can leave the spring all alone, since the boost controller is gonna take care of all that. sweet. thanks again!

[NemeGuero]

Get an MSD BTM if you don't want to spend the money on a tuned ECU. Then you can bump up the boost to easily 15-18psi.

[pacefarm]

what are some other alternatives to the msd btm, aside from tuned ecu's?

[orion::S14]

A blown motor.

It's either:

1) Retard base timing (safe until ~230-240rwhp)

2) Tuned ECU (good for whatever amount of power you want)

3) BTM...which is still a piggy-back, good until ~300rwhp I'll bet, but kinda crude.

That's it.

- Brian

[pacefarm]

isnt emanage capable of adjusting timing to a certain extent?

[NemeGuero]

E-manage should be able to.