Boost problems whilst mapping
 

I have a UK Hawk STi running a stock intake system but with a good panel filter, a 3" exhaust and the standard turbo modded with a billet turbine wheel. The previous owner had the car mapped in 2014 at 348 bhp, at around 1.3 bar boost.


I'd previously been advised there should be plenty of room for upping the boost a bit and getting more out of the engine, so the car went in for a remap at Engine Tuner down in Plymouth (very impressed with them by the way).


Martyn found that the car wasn't able to hold more boost. He did get a fat increase in mid range torque for me (peaking at 360lbft), but nothing more at the top end and no more power. His comment was the boost system wasn't performing well, possibly because of the spring in the actuator not being strong enough, or due to the restrictor pill or boost solenoid. His recommendation to get more power was to go for an SC42 turbo (good choice) and fit it with aftermarket headers and up-pipe. All sensible stuff, but.....


Having thought about it, my question is, shouldn't I be switching to a 3 port boost solenoid and remapping? That would mean a new solenoid and ditching the restrictor pill. Also, if I change the turbo, does that mean I don't need to improve the boost control because I wont need to run more boost to make a lot more power?:Suspiciou


Cheers :)


David

how much money do you wan to spend? new turbo & stuff = approx 1500

new actuator = £100

if its a std 2.5 bottom end i wouldnt be pushing it anymore than what its already at tbh

boost solenoids are usually happy enough at that level anyhow - and if it was a duff solenoid surely he'd have had a spare he could swap out on the day to have checked for you

could have probably also tested the actuator also come to think of it

It's a forged engine so well able to handle 400 bhp+ (limiting factor being the standard rods).

test the actuator crack pressure with a mityvac, to see if that's the issue...

Might be worth testing the actuator by using a piece of hose to connect the boost outlet nipple directly to the actuator (taking out the boost solenoid, restrictor and t piece) and using a cheapo Bluetooth obd adaptor and phone logger to see what the boost is doing.

Connecting the actuator like this should give around 10 psi ish.