paul & bad jac

I read in banzai that aps intercoolers from g-force seem to loog the biz, anyone have figures or experience wirh replacement top mounted intercooler for MY98?

john banks

IMHO, better to change the turbo first, and then when you want a bigger intercooler go straight for a FMIC. Don't get distracted by watersprays and uprated TMICs if you want big power.

paul & bad jac

thanks john, but budget and wife has its limits. i can hide the intercooler easily. DOH!

john banks

You can hide a turbo better

what would scooby do

I have order an APS topmount just because my existing sti one is bent.. The MRT one is supposed to be the best but is mucho expensivo..

Edcase

You'll have trouble hiding that:



Only a couple cubic inches smaller than their FMIC plus you get the pressure drop etc. Just make sure you get your downpipe lagged and the heatshield refitted if you have your up / downpipe done!!!

And get a bigger scoop and the matching APS air splitter and seal so the air goes into the full area of the I/C.

sparkster

Is it true that if you get a FMIC and your only running a TD04 that you will loose performance? The reason i ask this is if you upgrade your turbo and are still running a very inadequate intercooler, wont you have major problems with detting?

Could you not get the FMIC first, then wack on a Dawes Device and take the TD04 up to stupid levels of boost until it goes, then upgrade your turbo?

john banks

There are two sides to a turbo.

Consider EGBP and compressor efficiency.

You can get a happy 330 BHP with the standard intercooler, but you won't get 300 BHP on the standard turbo.

It is not a case of either turbo or FMIC, really need both to do it well.

[Edited by john banks - 5/27/2003 9:21:04 PM]

sparkster

John, what does EGPB stand for?

sparkster

sorry EGBP

sparkster

just read another thread. Back Pressure

john banks

Exhaust gas back pressure. Small turbines give lots of this when pressed hard. This results in pollution of the fresh air/fuel charge from reversion during cam overlap since manifold pressure in this situation is lower than EGBP. This is a big cause of detonation, and requires quenching with excessively rich air fuel mixtures and retarded ignition timing. It is a situation where increases in boost lead to smaller gains and eventually losses. This point on the MY99/00 TD04L-13G appears to be at about 1.1 bar at 6000 RPM, better keeping it under 1 bar up there, although the turbo on the WRX is a slightly bigger version it seems. The 1 bar at 6000 RPM on a small TD04 is inefficient compared with 1 bar on a larger turbo which gives a happier engine.

On the compressor side of the turbo, a small compressor pressed hard will give a hot compressor discharge, which will work the intercooler harder.

If you use larger hot and cold sides to your turbo you have more lag and a higher boost threshold, but far greater airflow, far more resistance to detonation and the ability to run an engine to very high power outputs with relative safety.

Engines prefer a bigger turbo unstressed than a smaller turbo working hard.

sparkster

great email John, thanks. In an ideal world, i think we would all like to fit a new turbo and FMIC at the same time. I was going to take the next six months to save for a decent intercooler but thats made me think about buying the turbo first.

Very interesting about the detting situation. A bigger more efficient turbo and less detting. I like the sound of that. I can run my engine under safer conditions until i can afford the FMIC.

paul & bad jac

cheers for all the info John, all sounds like you said bigger turbo first. Im not particular about going above 300 bhp as the car is 270 ish and similar torque figure. i thought stupidly a cooler charge woulg help performnce as felt on a cool damp day.

Edcase

Not stupidly at all. At those kind of power figures you will see a benefit as you will be able to run slightly more boost without det. Its not only the cooler charge, but also the pressure drop.

As I said just make sure you lag your d/pipe, and get the bigger scoop and the seal around the I/C face.

john banks

Agree not stupid, I just think that it is not the best order in which to do things for most gains. Rather than improve the intercooling better to sort the source of the problem which is the turbo. The factory intercooler will be fine for considerably more power if you don't heat the air as much in the first place.

IMHO, changing the turbo gives you a big leap compared with changing to an upgraded TMIC or FMIC. A FMIC thereafter gives a nice further gain if you want to run high boost.

I think you would be back where you started with charge temperatures with most uprated TMIC by adding only 1 or 2 PSI boost.

I have seen a VF23 at Knockhill at 1.3 bar on the standard TMIC run 10C cooler charge temperatures than a TD04 hybrid on the same day on uprated TMIC also at 1.3 bar.

Despite the 04 having a bigger compressor and the better intercooler it was running far hotter. I reckon the 04 hybrid I had was similar size to the 04 on the WRX from the way it boosted. Beyond 1.3 bar on a cool trackday it was really struggling with intakes in the 50s pretty quick.

A good FMIC and turbo at far higher boost will keep things maybe 25 C lower. Worlds apart.

[Edited by john banks - 5/28/2003 6:53:02 PM]

Edcase

John, whereabouts in scotland are you when i get round to my remap?

john banks

Bit far from you - in Fife. You're better seeing Bob I would have thought?

sparkster

Edcase,

any chance of explaining the benefit of wrapping the down-pipe and the up-pipe if thats the case. Yes ive just had up-pipe and down-pipe fitted and i'm now thinking i should have got it wrapped. Has it got something to do with unwanted heat transfer into the area of the intercooler? Is it also the case that wrapping the down-pipe will mean less dense air through the exhaust hence less back pressure??

If its beneficial, i might make this down-pipe wrapping a weekend job

Edcase

JB - Yeah but could always turn it into a bit of a holiday Always wanted to do Scotland.

Sparkster - basically yes. Especially with the sti and aps intercoolers as they hang straight over the top of the downpipe, and so as heat rises, you don't need to be sat still for long before you end up with a big heatsink on top of your engine!!

Most aftermarket downpipes wont fit with the standard heat deflector without cutting / modifying it to shape, but it is well worth replacing it and wrapping the downpipe with lag (someone mentioned a company called proven products. About £22 IIRC.

Also quietens down the engine bay.

crusher

So John,
If you had a my99 with a open neck downpipe, scooby backbox,ecutek 2,standard (or MRT/APS intercooler)standard injectors(walbro pump) what would you say was the turbo to go for as a next mod?

nom

I reckon the TD05 may get a mention here...

sparkster

ide really like to hear what the best turbo upgrade for a WRX would be (money no object)

nom

Totally depends on what you want - there's no 'best'. Speak to someone who knows turbos & is impartial - Mark (Lateral Performance) would be my choice!

MurrayZA

I have a MRT TMIC on my 01 WRX that I havent pushed too far yet.
It only deals with 0.95 bar of boost from the TD04. So, maybe I could throw in a TMIC related question too - if I have a MYXX car with a standard TMIC that runs no ignition retard (i.e. performs optimally to the point that an extra psi boost would cause retard), if I add a MRT / APS TMIC, how much more boost should I be able to run safely (with no retard) ? Toughie.

crusher

John,what do you think...

john banks

yes crusher.