WRX Wannabe

Am i safe to run 1.4Bar on standard internals?

Car is 260Bhp at the moment but am looking to upgrade to 290 running 1.4bar!

I am just a bit worried about the pistons

I may also need a large FMIC to help me

Uk classic turbo 2000

john banks

What turbo? Remember that a decatted P1 or STi running 1 bar at the top can do about 290 BHP and they run small turbos. Why do you need 1.4 bar? (don't even think about trying to run a TD04 at 1.4 bar at 6000 RPM it will either not do it, kill itself trying or kill your engine trying).

WRX Wannabe

That's what i have been told the re-mapped chip will run at?

The turbo is standard for a uk 2000

john banks

Boost levels you are being quoted are undoubtedly midrange boost levels which will affect the torque. It will not be running 1.4 bar at peak power so "290 BHP @ 1.4" is meaningless. 290 lbft at 1.4 bar might be more realistic.

IMHO you are better doing a bigger turbo before doing a FMIC.

A FMIC will not protect you from the adverse effects on exhaust back pressure, pumping losses, end gas pollution of fresh charge from a turbo which simply has too small an exhaust turbine and housing to make good power easily.

WRX Wannabe

Thanks

Fredysan

Hi John:

You said

"don't even think about trying to run a TD04 at 1.4 bar at 6000 RPM it will either not do it, kill itself trying or kill your engine trying"

Why, in this conditions, the turbo could kill the engine?

Regards

Tim W

iTrader: (1)

Freddy, the turbo going pop could result in all sorts of problems like oil starvation, oil contamination or even bits of the mangled impellor some how getting through the intercooler to the engine. Whatever killing a turbo big style (which 1.4 bar on a TD04 could happen) isn't good for engine life!

Either way 1.4 bar on the diddy little TD04 is pushing it and asking for trouble!

nom

...and killing the engine comes from the fact that any given turbo has a 'flow' that it works best at. Push it past that flow, i.e. run it at higher boost than it was designed for & all it ends up doing is heating the air more & more rather than compressing it. The intercooler is able to drop the temperature of these gases a certain amount, but whatever, the hotter the charge into the engine (the air that has been pumped out of the turbo), the more it will heat the cyliders, etc. & the more likely it's going to something nasty to the engine. Hot charge promotes det amongst other things, det increases cylinder temps, & round & round you go in the viscous circle until the oil film breaks down (the piston stops moving & bye-bye lots of bits of engine), the plugs or other object in there gets hot enough for pre-ignition (then hello hole in piston) just to name a couple of fun things that can happen.
Also, running out of the efficient area of the map (too high boost), the 'thinner' (as it's hotter) the charge will be as well, meaning that it's quite possible to get less power at higher boost - remember that the power comes from mixing the correct mass of fuel with the correct mass of oxygen - not what pressure the air in general is at. Hence running a larger turbo - which heats the air less as it'll be likely to be more efficient at higher flows - can easily produce more power at the same boost because the charge is cooler. Because the charge is cooler it may not be necessary to have an FMIC (less heat to dump).

Hope something in there makes sense

john banks

It is at 6000 RPM that 1.4 bar would worry me, in the midrange it would probably hold together fine since at PR 2.4 it could still be 74-76% efficient. Agree with Tim and nom.

359 to 377 CFM for PR 2.0 to 2.1 at 85% VE at 6000 RPM on an EJ20. This is about the compressor's limit suggesting a manifold relative pressure of 1.0 bar at 6000 RPM should be considered a sensible maximum IMHO (you are only just over 60% compressor efficiency). This ignores the turbine side which is also getting choked. It ignores the adverse effects on ignition timing from charge temperature and exhaust back pressure.

1.4 bar is just about OK at 4000 RPM from the point of view of the compressor (74% efficient), by 5000 RPM it should be brought down to about 1.2 bar (65% efficient), then 1 bar at 6000 RPM.

In reality you will struggle to run a lot more at 5000+ RPM anyway unless you go silly with actuators.

Tim W

iTrader: (1)

In other words buy a bigger turbo

MrContro

How much bigger is a TD05 in comparison to a TD04, with regards flow, and efficient boost running potential.

Thanks

john banks

You can run enough midrange to kill a gearbox, taper to about 1.5 bar at 6000 RPM.

MrContro

Thanks John

WRX Wannabe

Well i am not gonna do the chip upgrade now then

Looks like i need to think about a bigger Turbo

Chungster

Go on mate, you know you want to!

hehe

WRX Wannabe

Ha HA or i could just buy an STI

Tim W

iTrader: (1)

Wanabe, don't bother with an Sti, we managed to squeeze my UK car into the 350 brake 300lb/ft area of operation as have many others for the same moeny as it would have cost (ie the same mods) to get an Sti up there

You need both mods anyway to fully appreciate it...oh and bigger injectors too if you plan to run more boost....

911

There is obviously a lot of learned gentlemen here who seem to know what they are talking about.Presumably the theory has been tried and it works, SO......

Why can't you all get together a set of specifications for the not-so-sure idiots like me to look at?

Bit like:

Stage 1 V3 STi, stock turbo/decat/stock ecu = xxx BHP/Lbf
Stage 2 ditto xyx tubo /decat/GEMS = yyy BHP

There must be set spec of components that work together well without making for a grenade engine.

I am sure there are a lot of us who would want to see such a listing on the Scoobynet?

Graham. (a hillclimber looking for a better engine)

john banks

Opinions will vary though. Figures for various products will be debated.

If you were to post "How do I get a reliable 350 BHP hill climb STi 3 for £xxxx/xxxxx" you would get very many opinions

911

I am sure you are right John, but the Impreza has been around several years now, and I'm sure there is a common denominator'appearing' from the experience of the many who experiment?
My V3 STi is stock bar the Blitz boost controller set at 1.25 bar and the magnex turbo back exhaust, it has been RR'ed at 314 bhp.
It is a great engine as it is, so where do I go next?

An ECU? but with bigger pump/injectors? Or does the bigger turbo come before them?

Let me ask you, just how do you stretch the V3 I have to 360 bhp? If I believe Town End Garage a GEMS will do it. Is that all there is to it? £1300 and Steve Simpson = 360 bhp?

I would be interested to hear from you and the others who seem to understand the Impreza engine so well. If it were a 911 I could take you through the route to 280 bhp easy, there is a very proven 'formula' to follow.

Hope you will open up the debate John, Regards, Graham.

john banks

I would say, ECU, fuel pump/regulator, injectors, FMIC, turbo, induction, turbo inlet pipe, +-headers/uppipe.

nom

And the type of ECU has bugger-all to do with how much power can be produced - at least, until you start getting in to the realms of 8 injectors & so on - all it does is enable the mapper to get the best from the kit on the car. Possibly a clearer way to phrase that is that the kit on the car can't do anything until it's made use of, and the way to make use of it is with a knowledgable mapper. And the tool the mapper uses is the ECU.
In case you haven't spotted, I'm not too keen on the companies out there that claim they can increase your bhp by x amount by simply changing to their ECU - what they usually mean is by reducing your engine's life by 50%, they can increase power by 20%. Well, that's nice
So... kit that enables the power, followed by finding a good mapper that can make the best of it. You could get 360bhp, albeit very briefly, with a Gems, but you could probably get there as well for the same length of time with a Dawes for 50 quid...

There endeth the sermon
Except for the agreeing with John bit - change loads & you can get 360 no problem

911

Gulp! Didn't say that in CCC about GEMS!!

Realy appreciate your help, very tricky to cut through the BS out there.
Graham.