john banks

Sorry Tony. P1 has a boost target of 15.7 PSI midrange and a lot actually make over 16 PSI. To take a midrange boost figure and extrapolate it to create an imaginary peak power figure is just that... imaginary. It ignores compressor inefficiency at high boost with resulting increased charge temperature, increased exhaust back pressure, and the resulting requirement to retard the ignition, which then further raises EGT, resulting in a vicious circle of detonation. You would be a brave man to run a VF28 at 22 PSI especially with a top mounted intercooler. 22 PSI gives a PR of over 2.5... go and have a look at even a VF23 compressor map and think again.

I would not run a VF28 at peak power at much more than 3 PSI above P1 factory - ie 14.6 to about 17.6 PSI. Try and do that with the factory ignition map and it will det unless you have a FMIC.

Steve do you count as a Southerner or a Northerner Mr F likes to knock a bit off for temperature correction to make up for his midget gearing

[Edited by john banks - 10/2/2002 11:11:34 PM]

davy b

i have a full decat p1 with k+n induction kit and hks dump valve.
i would love to get up to 320-330 reliable hp, what are the best mods to go for? i am thinking about a tek 3 custom map but need other ideas from people that have got bigger hp. also will i need a knocklink and a lambdalink to keep a safe gaurd over the enigne.
p.s. i would like to keep on standard turbo and intercooler.
forgive me for asking so many questions but i want to spend the money on the proper mods to have.

thanks
davy b.

P20SPD

iTrader: (1)

i would be very surprised if you can do it on standard turbo and standard intercooler. You may touch 300 to 310 with the right mods, although not nessecarily safe ones, if you retain standard turbo and intercooler.IMHO

john banks

310 BHP and 290 lbft might be reasonable with your mods if you ran about 19 PSI dropping to about 16-17 PSI at the top. To get more you need a bigger turbo, or get the VF28 hybridized, or an optimistic dyno, or excessive temperature correction on a pessimistic one

Have a look for Mike G's thread - this was hotly debated recently...

Razor2001

I thought that a standard STi-7 (JDM) with full turbo back decat would achieve 300 bhp and 290 ft. lbs. ? Is this unrealistic ?

Cheers,
Ray

Razor2001

tell it like it is, I am not afraid

john banks

Depends on what dyno? People said similar about the P1 but on a lot of dynos this would be optimistic.

Razor2001

Really,

So one can't get a measly 24 bhp (276 - 300 bhp) from fully decatting an exhuast turbo back ? What would you say is realistic, 10 bhp and 10 ft. lbs. ?

Cheers,
Ray

Razor2001

Ok, trying to justify why I spent so much money on a full deact from turbo back if only good for a few bhp and ft. lbs. So help me out....I guess it has at least made it safer to turn the boost up 1 or 2 psi's as the EGT' should be less with no cats or restrictions from turbo back ? (I read many, many EGT and MBC threads and never really got a definite answer, so hoping someone can clear it up for me here

Cheers,
Ray

john banks

The gains are not as big as we would like them to be?

Razor2001

Well I was hoping of gaining 25 bhp and 20 ft. lbs., but I guess 10 and 10 is more realistic, so yes ! I was expecting more

Ray

davy b

310hp and 290lbft would be great at the moment but if i was to go the uprated turbo road later on to get the 330hp what is the best turbo to go for with not to much lag, also would i need an uprated fuel pump and other mods to get to the 330 mark?.

davy b.

TonyBurns

iTrader: (3)

Davy dont listen to them
Right to start with a standard P1 runs around 14psi, they also have uprated parts so are good for more boost than a uk car, now if you work on the principle that running say 22psi safely on the STi engine or even 20psi and the average increase in bhp to psi is approx 7bhp that gives you 7x6 which equates to 42bhp, now adding 42bhp to 276bhp rates at about 318bhp so not far short of your required 320bhp
To get this safely though i would purchase a FMIC and something like a GEMS or Link ECU that can hold more than one map (just to show off )

Tony

steve McCulloch

John

What a sly comment about the temperature correction - I laughed loads - Mr F wont be happy

I think we should all award ourselves with temp corrections when we want that little... extra

Andy.F

Grrrrr Mr F was robbed of bhp on his last RR run due to -ve temp correction but then when you don't need it Who cares

SCOOBY NET

RICH WILD

No one seems to want to answer your EGT question Razor, so I'll have a go.

If I'm wrong, I'm sure John will correct me as he certainly knows his onions more than I do.

Decatting will make the car breathe better which will have a tendency to make it run leaner, which should raise EGT rather than lowering it as you thought.


Cheers

Rich

TonyBurns

iTrader: (3)

John,
i think it depends on the car really for what boost its pushing, there are some P1's that can run a steady 14psi and have the factory 276bhp then there are others that run less than 270bhp with over 16psi, then again there are P1's running 16psi with over 300bhp
But like i put on the bottom of that post, to do it safely id run a FMIC and something like a Link or GEMS ecu (and maybe an APS turbo )

Tony

john banks

More likely BS dynos Tony

Razor2001

Thanks Rich

Can any of the pros confirm this ?

Cheers,
Ray

Andy.F

Don't know the 'pro's' view but here's mine.....

I can only speak from experience on my own car, here's what I found.

Initial Decat with no other mods = reduced EGT's 2 perceived reasons for this, 1 - reduced exhaust backpressure (pressure ~= heat) 2 - The resulting small increase in airflow moves the fuel map to a richer zone.

Slight increase in boost pressure (0.8 > 1.0) after decat = increase in EGT, presumed due to fuel pumps limited output causing pressure to drop off at higher RPM and possibly increased ignition retard at new load.

Free flow exhaust system = EGT dropped again

Free flow induction system = EGT dropped again

Fitted new fuel pump = EGT dropped again

Hiked up boost pressure 1.0 > 1.3 = EGT just back up to pre decat level (700C) but power up by 50bhp on standard.

If there is anything to be taken from this it's get the air flowing freely before trying to pump it in harder. When I tried even 1.2 bar without the exhaust and induction it would det like hell when it got hot.

Razor2001

Excellent info Andy, thanks !!

Finally, what car are you running ? Year, UK or JDM etc ? and also a list of mods would be super (ie: what induction kit)

Cheers,
Ray

babber

What EGT temperature is normal for MY99 ? I understand that it rises once thrashed, so a normal and a driven hard figure would be good

Cheers Phill C

Razor2001

bttt

Andy.F

It will depend on where you have the probe and what, if any, mods.

Std my car was 600-620C at 70-80 mph cruise. Rising to 700C during severe road thrash (at 0.7 - 0.8 bar).

Now it runs 580-600C cruise and 750C road thrash (at 1.7 bar) , up to 840C after 5 laps on a track day.

My probe measures EGT at the uppipe inlet to the turbo.

babber

My EGT probe in fitted before the turbo where to two manifolds join. I'm seeing higher temperatures than you are

Cheers Phill C

john banks

The nearer you are to the headers the higher it will be. With a TD04L at fairly high boost I used to get 760 C max just before the bottom of the uppipe.

Trout...

Interestingly my EGTs are much higher than Andys - to run at 600-700 I would have to pussyfoot around, even off boost, and even then piling more fuel in only cuts it a little.

On track I need to add about 1.5% more fuel to keep it below 900degC.

Trout

TonyBurns

iTrader: (3)

Re EGT,
Where does everyone take their readings from?
I know that my downpipe has a position at the top for a sensor (and i would have thought that this is the best place to take the temp readings from) but where is the most accurate place?

Tony

Andy F.

I measure my EGT by a 'K' type thermocouple. It is a very fast responding 1.5mm diameter probe. I have a hole drilled into my turbo, just above the uppipe flange. The probe only protrudes approx 5 mm into the flow, I believe ideally it should be 1/3rd of the way in ?
Perhaps that's enough to cause it to read a bit lower than Trouts ?
Or maybe it's because I'm making so much less bhp

Andy