hi

just wondering whats the max Bhp can a TD04 take? with a STI v4 interloor??
what mods will take it to its best?? its a MY98 UK car, as i dont want to go to the TD05 rote....

current spec:

full decat
sti v4 intercooler
fse reg
walbro pump
mapped ECU to 1bar

thanks guys

 

Most power seen from a TD04 to my knowledge is 312bhp at PE (which are generally fairly optimistic rollers) on a modded bugeye, exhaust, inlet, APS top mount, aggressive map (something like 1.25-1.3 bar, IIRC). Not aware of any others topping 300, although I know a few other bugeyes made the 290s on the same rollers. MY98 version of TD04 is allegedly slightly less good at top end power than bugeye, with the right supporting mods, probably 280 ish is realistic limit.

 

Hades, why do you think this is? Is it because the headers are different, inlet, topmout or a combination? I thought the new age WRX had 380 injectors as well?

F

 

It does seem that a decat/TEK'd bugeye will make ~280bhp at PE, whereas equivalent mods on a classic yield on average 5-10bhp less, I'd guess. The standard TMIC on the bugeyes is a bit bigger, which should help, there may be other things that do help too. However, I have heard from a few separate sources that the turbo itself is actually (very subtly) different, and is a touch better at higher flow/boost. I don't have data to actually confirm that, but think it is probably true.

 

I wonder why they went back to 380's though?

F

 

possibly for better fuel atomisation, probably because they could be supplied at a better price!

 

Classic is td04l, new age td04h, I think. Bigger exhaust wheel +/- housing is the difference?

 

on my00 uk im getting around the 270 mark now
and will be chopping in me td04 for a vf34
considered vf24 or 28
but on recommendation(andy.f ;-))
im gonna go for the vf34
not as dear as you may think and you can always sell the tdo4

 

TD04 is good for 280 BHP on a MY98.

Thats why my uk MY98 went for a VF24 off a STi4 (£150), with 440cc injectors (swap for standard spoiler)
full decat, (£300)
fuel pump,
fuel regulator,
KNi filter with cold air feed and scoop (£40)
Tilted and split standard intercooler with water spray (free)
Lightened flywheel and AP clutch (£700 for both)
PE remap (only people to do a Tec style remap on a MY97/98 on original ECU £580)

I am now seeing 311 BHP and 290 LBF

Neal

 

Si - thanks, that kinda backs up my vague recollections with a little more fact!

Floyd - Maybe it's because 380s are still good enough for a bit over 300bhp if you uprate the pressure, which will take you very close to the limits of the new age WRX gearbox?

Also worth noting that the WRX and STi injectors are apparently the same, with just a different end-cap microwelded on; IIRC the injector is capable of something like 650 or maybe even more if you cut the end cap off. There's some company over in the states that does this.

That implies to me that the choice of end-cap would be fairly arbitrary, therefore I can only imagine 380s are used for fuel atomisation/spread etc, particular at tick-over etc where you have very low Injector Duty Cycles.

Only thing that may undermine this is that IIRC some of the people in the states using the "de-capped" injectors, which then don't have the nice spray pattern still claim to get decent fuel economy, idle behaviour etc once the map is set up right.

 

P.S. As Neal says, no doubt you'll get more from a VF series, 34 or 35 seem to be a favourite (more recent design than the VF24), as they can get ~340 or so, with better spool than a TD05 (which could produce more power still), but obviously worse than a TD04. The twin scroll VFs are capable of a bit more power AND better spool, therefore an ideal compromise, but need new headers, up and downpipe etc so are not the cheapest option.

However, talk of other turbos has been done elsewhere; Neal's first line is probably the answer to the original question - about 280bhp on a MY98.

 

Just to back up the rest here. I had 274bhp on a MY97 UK (TD04) only mods were a full de-cat, HKS ind kit and a Dawes set at about 1.1Bar