BoxerFlat4

OK, after the rolling road day at Well Lane, I'm both happy, and puzzled. Got a good result :-

STi1 Wagon (full decat Mongoose system,) 282bhp @ 6416, 266lbsft @ 4800, 19psi

:- but the PSI to power ratio seems odd. Holding plenty of boost, but the power figure seems quite low. Other engines on the day where pulling as much boost, but ended up with higher BHP figures. Although torque is my interest, I was curious if anybody had any ideas ?

My theory is that with the decat exhaust, my mixture is becoming lean, and holding back the engine. There was no detting, so I don't think it's fatal, simply reaching the limits of the current injector/fuel pump combination. Was planning to install the Apexi Power FC, but would I be better off spending my £650 on the fuelling system first, and throw some gauges at the car as well ?

Answers on a postcard....

[Edited by BoxerFlat4 - 10/28/2002 4:12:09 PM]

David_Wallis

i got plenty of torque

with 22psi boost.

David

BoxerFlat4

Yes David, but your's ain't standard ! And I saw you running around under the car at Well Lane, as well !


Any (useful) comments, anyone ?

David_Wallis

yeah... blew an exhaust gasket on the way.. that will teach me to use the orgininal's

Besides mines pretty std

David

David_Wallis

btw..

I run phase 2 rails with 550's, parallel feed to the rails, Escort Cosworth Fuel Pressure Reg, and a Walboro uprated pump.

Surge tank next.

David

BoxerFlat4

That was my thinking, upgrade the fuel pump and injectors first, so I can get a decent amount of fuel into the pistons, before worrying about the ECU side of it.

Still haven't looked at my ECU yet either, it's clearly some kind of STI unit, hopefully will find the time this week to crack it open !

annointed

You will need some form of engine management if you're going to upgrade injectors, as the stock ecu cannot handle bigger injectors alone. I'm running a Power FC on my '94 WRX, and it is a fantastic unit, although if you want datalogging on a laptop, look elsewhere, as the Apex'i laptop software is only available in Japan. You could also hook up an Apex'i S-AFC, which is a fraction of the cost of the PFC, which would leave spare cash for injectors/pump.

Mark

BoxerFlat4

Thanks Mark -

Can anyone else comment on the high boost/low power scenario I seem to find myself in at the moment ?

Chris.Palmer

I'm guessing from the - relatively low torque (in comparison to BHP) & the fact that this is at 4800 RPM that your car has a small Turbo.

Not sure of the spec of the STI 1 - but I know early Wrxs originally had TD04s then later went to TD05 - as on UK Models Pre 97. If this is the case then maybe its running out of puff at higher RPM.

Chris

What PSI does it peak at & what does it hold & at what RPMs?

[Edited by Chris.Palmer - 10/30/2002 11:51:15 AM]

BoxerFlat4

Chris - thanks for the reply.

I haven't got a mapping for PSI to revs, just a final boost reading from the rolling road. Looking at the graphs, I can see :-

1. Torque - is reached fairly quickly, 250lb@4000RPM, it then drifted up to 266lb@4800RPM, then started drifting down again. There are no "bumps" or "spikes", a relatively smooth progression up and then down.

2. BHP - again, relatively smooth graph, a small plateau between 5200-5700RPM, where it stayed at 270BHP, then started climbing again up to 282BHP@6400.

Is the torque figure low, given the BHP ? I felt that it was reasonable, certainley to drive it feel very torquey. Regarding the turbo, I haven't had a chance to inspect the make yet, I do know that the estate STI's have a higher compression ratio - on my car it's actually supposed to be rated for 250BHP. Until the decat ent on recently, the turbo wasn't really spooling up until 3000RPM, now you can hear/feel it from 2000RPM.

Many thanks, BTW... more feedback please !

Edited to add, I believe it reached and held 19PSI - 3PSI more than with the old exhaust on !

[Edited by BoxerFlat4 - 10/30/2002 12:08:13 PM]

Chris.Palmer

Have a look at my home page for some comparison. Only 269 bhp & 248 lbs/ft torque though.

Whats your Torque / BHP at about 3000 RPM - TD05 will only just be spooling whereas TD04 should be pulling.

Look at the PE overlay graphs of my car running 16psi & 13.5psi on sussessive runs with PPP (with/without Dawes) - above 6500 - the turbo is just supperheating the air & the BHP is almost identical - but at lower revs the torque & BHP is significantly different.

BoxerFlat4

Chris -

Here's my printout from the rolling road session (excuse the marks on it, it was fu**ing freezing in Batley, and wet ! )



Let me know what you reckon - I'm looking at yours now ( oo eer ! )

Chris.Palmer

Oooh - may have to eat my words a bit now - it all looks fine - I'd be happy with that

So we're back to the original question

Fuelling's been discussed...

How about cooling? I'd be interested to see how much your graph changes if you were to lose a couple of PSI?

You may be pleasantly surprised.

BoxerFlat4

Not sure - I've got an Apexi Power FC on order from Japan, which was supposed to go to a customer, but if they don't want it, I may plug it in and play with it a bit.

I was going to up the fuelling and boost, and see what happened. Problem is, I need to get back on a rolling road with several different maps to see what works/doesn't. Looking at those maps, what turbo would you say I've got? If it's the smaller, its probably a waste of time trying to push it any harder.

Pavlo

FMIC?

Decent map?

Decat will often result in running richer. The ECU runs with a Mass Air Flow sensor, so it knows about all the air going into the engine. The standard maps richen massively at high load/rpm, and a decat, boost and induction kit will serve to push you further into the rich zones on the map.

I suspect that a certain amount of this is to overcome the poor performance of the fuel pump.

STI wouldn't have had a TD04, the only cars that appear to have had them were some jap wagons, and I wonder how many of those came like it from the factory.

Bigger injectors is a must on the early engines with only 380cc injectors.

Things like ignition advance also play a big part, Davids car runs with about 2 degrees more advance than a 96 prodrive map, and that's at 22psi compared to 13psi. But it uses water injection and a big FMIC to make this possible. Trout reakoned on 1 degree being worth about 7ft-lbs of torque on his engine, so not to be under estimated.

paul

BoxerFlat4

Cheers Pavlo -

Decent map - I know my car has an STI ECU in it, which itself raises some questions. Need to open it up and copy out the data to see whats inside.

FMIC - If only I could afford that ! My insurance broker would love it, though....

Water injection - Something I have considered, may need to re-investigate.

Turbo/Injectors - Problem I've got is, although I know what the car SHOULD have, what it ACTUALLY has is another thing. These STI 1 engine spec seem to vary from car to car, even models close together on the assembly line. Remember, the STI 1 engine was hand-built, and STI seem to throw whatever was handy that day in ! I'd love to be able to upgrade the turbo, but costs will probably prevent it - injectors are something I need to look into. Need to find a supplier first !

BTW Paul, my car is a Jap wagon....
[Edited by BoxerFlat4 - 10/30/2002 11:28:14 PM]

[Edited by BoxerFlat4 - 10/30/2002 11:29:51 PM]

annointed

I imported a '94 jspec WRX wagon front clip, and it came with the dreaded tiny TD04. But the cool funnel heat shield (with a screen mesh at the top, linked to the bonnet scoop backing plate) that came with it is pretty neat...Subaru should have stayed with that idea.

But the TD04 is tiny. It says TD04 right on it, and will have a Mitsubishi logo on it. I imported a TD05 from Possum Bourne, and it bolted right up, so if you happen to have the tiny TD04 blues, you can easily bolt up a TD05 for next to nothing, and make much more power than the TD04...but like some others have suggested, it's more than likely that your car did not come equipped with a TD04.

I have a question...those dyno graphs, are they referring to power at the wheels? Because BHP (brake horsepower) = crank hp, as far as I understand. 260+ whp is highly unlikely with a TD04. In fact, even the TD05 probably can't make 260+ whp without upgrading the stock 380 cc injectors, pump, and intercooler.

annointed

I just peeked at your dyno graphs again, and you definitely have a TD05. My '94 WRX wagon driveline (swapped into a '94 Impreza sedan), makes 235.7 hp @ 6100 RPM, and 226.6 ft-lbs @ 5100 with the TD05 that I swapped on in place of its TD04. I would post my dyno charts if I knew how to, but suffice it to say that our peak numbers occur at nearly the same RPM, and spool up characteristics are very similar, although my torque curve rams up like a rocket, and yours comes on smoother. The TD04 can't hold full boost to redline, and the graph after 6000 RPM would drop like a rock if you had a TD04.

If you'd like my charts to see what I'm referring to, I can email them to you.

Mark

Edit: BTW, my dyno figures were at 15.5 psi.

[Edited by annointed - 10/31/2002 4:04:30 AM]

alanjack

My insurance only went up £20 for FMIC.
By the way I have the Power FC and I got 289BHP and 286lb/ft.
If you have the Power fc you won't need the S-AFC, so that saves money in it's self

annointed

alanjack, nice figures at the wheels! Did you run your beast in the 1/4 mile? Sounds like a mid 12 second car, easily. What other mods do you have besides PFC and FMIC?

Are you using the PFC to control boost (with the optional boost control module), or are you using a separate boost controller?

alanjack

Apexi AVCR is control the boost.