megrac

well i got this thing tuned today. i am happy with it but something is limiting it up the top as running more than 14psi just results in a bit more torque and shifts the peck power down the rpm range.
It was tuned on crapy bp96 as thats all i can get were i live.

List of mods
car is a ver3 sti.
ej257 block with ver3 heads bolted to it.
3in exhaust
40mm external wastgate
A steve murch td05/06/to4b witch surges like a big pig in 5th gear.
6kg flywheel
my99 sti clutch
brofec B boost controller
hybrid FMIC
possumlink ecu
550cc rx7 injectors
r33gtr fuel pump
gtb fuel pressure reg witch seems to run the perfect pressure of 52psi with the vac line off.

The injectors dutycycles are in the mid 90% at full nuts.(tuner was talking crap as i found it was no more than 75%)
I think 212kw atw on this dyno works out to be just over 360hp at the engine.
It makes 174kw atw at only 10psi.

Things im going to check are, pressure drop across the intercooler as this could have an effect on the surge as well as the power. Also maby puting my td06 exhaust wheel in and getting the compressor wheel changed to something else.
all this complaning but the car does fell bloody fast.

anyway here's the dyno plot.
http://img118.exs.cx/img118/2241/dscf21017qi.jpg

megrac

Man this must be some privite U.K only club, 200+ views and no bites.

I need some idears as to what would cause the power to just stop at the level it has.
i'm thinking its the td05 exhaust wheel but cant prove it as there seems to be people how have made much more with them, on better fuel though.

if you compare 10psi with 15-16psi you can se what starts to happen. i didn't print it out but if i run 14psi then 16psi the plots are on top of each other after 5500rpm and you have to start dumping fuel in to stop it knocking witch seems to me to mean some kind of exhaust restriction?

15-16psi v 10psi
http://img223.exs.cx/img223/4664/10psiv16psi6eb.jpg

this is my 2.5 v the old 2l runing 18-19psi witch is the blue line.
http://img196.exs.cx/img196/6483/25v2l3yp.jpg

911

Megrac

No exclusive club here!

I am no expert, but would comment that the mods made to the car are not the 'normal' run of parts in the UK, and that may be the issue to lack of response.

I should think the Possum ECU is very rare here so an unknown area.

Having just had my Sti v3 mapped with some 'normal' mods on it,I don't see why your car isn't a screamer.

Can't help but thing the root of the issue is the mapping to 'tune' all the components together.

Have you contacted MRT in Australia for help on the ECU?

If you are UK based, get a £700 Apexi FC in the car and get AndyF to map it.
The chances are all will come true after that.

not much help, but I would hate to think there was any exclusive club in Projects!

Graham.

AndrewC

Graham, the Link ECU is very well understood over here it's been around for a while and lots of people have used them very successfully although now admitedly they are getting a little long in the tooth, I doubt that is the issue in this case.

Megrac, have you measured your EGTs? or EGBP? I though you were using a TD06 turbine? What type of headers do you have on the car? Does increasing boost result in having to pull timing? My first thought would be that it is exhaust backpressure related.

Andrew...

megrac

thanks 911.
I live i New Zealand.
The car does feel fast as it has 344hp at peak torque (4700rpm) so there must be some torque there. I think that works out to be 384lb/ft and i do fell sory for my gearbox.
The ecu was maped by one of the best in the country so i don't think there's a problem there.
I would of used a 20g compressor wheel but there were none in the country at the time.
i did think about a power fc but got feed up with the maf signal going crazy with my short intake and bigger compressor wheel.
i did a pressure drop test on the intercooler and found less than .5psi so thats not bad.

megrac

Andrew, exhaust backpressure related. Thats what im thinking as well. No i still have the td05 one in there. The td06 wheel will be going in in about a week or 2.
I'm still using the factory headers.

yes using more boost than 14lb means having to pull timing.

AndrewC

Unported factory headers?

I think your figures are pretty much what would be expected with cast headers and a TD05 exhaust side, you could get more with tubular headers but will soon be EGBP limited again by the TD05 turbine. Pavlo on here and 22B used the 06 wheel in a 7cm" 05 housing with tubular headers on his 2.5 to great effect last year.

How much power are you looking for?

megrac

Yes unported.
I'm after about 400hp and no more as my gearbox will not like me.

Would you recomend me porting them? and also what are the key places to port them as there seems to be so much crap on forums about porting headers.

AndrewC

I would say you already have enough torque to break the gearbox

I'm no expert, but you want to remove any step reductions in diameter which may restrict the flow, you are aiming to reduce turbulance and increase gas speed. With a 2.5 and a nice big turbo, tubular headers would be the immediate choice. Having said that, if you are about to change the turbine wheel it will be interesting to see what effect that has.

Another option would be ported headers with a tubular uppipe, this seems to be a good combination on 2L cars aiming for max driveability in the 320-340bhp range (Disclaimer: IMHO and depending on rollers other mods blah blah)

Andrew...

Peanuts

iTrader: (15)

could you brew your own fuel?
small percentages of alcohol and octane booster would raise the octane level to assist you

megrac

I pulled the headers and turbo off last night.
I had a good look at how the ports, uppipe and crosspipe all line up and they all seem very good. I did port them a little and also peened the pipe inside the up and crosspipe to sit at the edge instead of there being that gap there.
I also found a crack in the uppipe.
I'm getting the 06 wheel put in the turbo later this week. looking at the size differance i think the 06 should flow alot beter.

Andy.F

I would say your 05 wheel has been clipped to far

Andy

megrac

thats 12deg. well thets what it said on the invoice. it will be nice having no clip on the 06 wheel.

megrac

I've put the turbo back on with the bigger exhaust.
The spool seems the same or maybe a tad better. it only feels ever so slightly softer of boost but feels much less strained on boost. i've only run it at 10psi as i need to see and more than likely change my air fuel ratios befor giving it heaps.

i'm going to order a techedge wideband this week so i can do my own tuning.

dowser

As per above - more than 7 degrees on an 05 exhaust wheel is a waste, IMO.

Am interested to hear how the 06 wheel goes, and what was required to fit it?

Richard

megrac

my exhaust wheel is a tc06 wheel from a mid 80's mitsubishi starion. the wheel is the same as a td06(55mm) not the td06h(58mm). the sharft needed to be machined to make it fit. i sold my td05 wheel for the same price it cost me to get the new one machined and fitted.

megrac

I got my wideband today so it was tuning time.

I went through all the lower load zone to get them all sorted first and it needed so much more fuel for the same afr every were. I've started out safe and tuned full load at 1.1-1.2bar at between 10.8-10.9 to 1 and the injectors are now at 95% at 6.9k. over the next few days i'll look at leaning it out a bit and slowly put a tad more timing back in as i had taken some out when it was runing the smaller turbine.
I'm just loging with the WBlin going stright into the link ad reading the voltage of the logs. i got techedge 2eo so it also has the display on one end.

so the change in turbine has made my injector duty cycle go from 75% to 90%+ to hold about the same afr.

AndrewC

It's worth wiring the 2E0 with RPM and MAP inputs and doing some logging from the Techedge as well to check things, it has a much faster logging rate that the Link and of course you get the AFR directly rather than having being through a DAC->ADC.

Sounds good though, you should pickup some good torque by leaning it out a bit in the midrange although this can get expensive

Andrew....