S3TH

iTrader: (2)

Have already spoken to a few of you about this and been doing some research to get my my98 jap STi 4 to 350/60bhp.

Here is the list so far:

Walbro fuel pump & FSE
550cc Injectors
FMIC or STi 7 top mount
TD05 20G Turbo
Knock link
ECU (unichip?)
Forged pistons (sti 4 renowned for piston slap?)

Already have induction kit, GD Cat back exhaust, Blitz SBC Boost controller.

Bit confused about up pipes and down pipes? Any reccomendations on wether i need to change these and if so what for?

Regarding the ECU, tempted with a unichip as there is a unichip dealer about 2 miles from my home. He mapped my vectra GSi and did a damn good job off it. I dont know if unichip is the best way to go though. Any other reccomendations for ECU and need a mapper in east of england tbh.

Will i need anything else?

Thanks.

S3TH

iTrader: (2)

35 views and no replies?

Boyakasha

iTrader: (2)

unichip is ok for a 'standard' remap but with the power you are looking at you should be using an APEXi Power FC or something similar. This will allow the mapper to tune the car exactly.

Marc

colin c

TD05 / 20g would be over kill for for 350 bhp IMHO, standard TD05 / 16g is just capable of 350 bhp, better mod might be a TD05 / 18g as it wouldn't be running as close to it's limits as the standard TD05 to produce 350 - 360 bhp.

There are far better ECU's available than the Unichip, Power FC is a very good ECU for the money, speak to Andy F as he can supply these and the turbo for sensible money. Motec, GEMS, Autronic and Link are also very good but nearly twice as expensive as the FC.

You will also need ported headers. A better option would be an unequal lengh manifold like the Groupe-s or GT headers, these will allow you to achieve 350 bhp useing far less boost pressure and you will also get good gains in the midrange torque helping with a smoother power delivery.

A good down pipe is also going to help no end even if it has got a sports cat for the MOT.

Don't expect to throw all the parts on your Scooby and instantly get 350bhp, it's not that easy

S3TH

iTrader: (2)

Thanks colin, the plan is starting to fall into place a bit better now.

wont changing the headers loose the flat four growl though?

colin c

I was in the same situation as you, I wanted between 350 and 400 bhp but I didn't want to loose the burble, yes you can get 300 - 400 bhp useing ported headers but you have got to run higher boost which results in greater temps etc. The easier and cheapest route in the long run IMHO is unequal length headers to keep the boost levels sensible, they can be worth 20 - 25 bhp with the correct mapping.

I have got the Gruppe-s unequal headers and they retain a lot of the burble at lower revs and just sound mental a higher revs. Headers can also reduce exhaust loudness aswell.

TopBanana

I wouldn't change the pistons personally unless slap is really bad

XRS

I thought the STi 4 had forged pistons already.