just spent the last week fitting a few upgrades to my uk 97 impreza,
its in for mapping this week and wondering what power i should excpect to see,
spec is
apexi power fc
walbro pump
440cc injectors@ 3.5bar
front entry TD05
3" turbo back exhaust
hybrid FMIC
parralel fuel rail mod

 

About 350bhp with similar torque. The turbo is the limiting factor in this set-up i.e. at 350bhp it's pretty much maxed out.

But even if you wanted more, it's not advisable on the std internals/gearbox.

 

nice to know that its maybe capable of 350ish, i am however only wanting around 320-330 at them min, i thought i was maybe being a bit optimistic looking for that power level.

 

my guess would be 320-330

 

^+1

 

Assuming the motor is running spot-on, he should see between 340-350bhp if those supp. mods are mapped to full potential (but all engines vary, of course).

From a purely 'numbers' point of view, I'd be slightly 'disappointed' if it didn't make 330+...

 

what sort of boost should i be running to see 330bhp?

 

around 1.4 bar

 

I'd have thought that the injectors would be struggling to provide 350bhp, even at 3.5 bar. The theoretical maximum power of 440cc injectors @ 3.5 bar is 346bhp, but personally I wouldn't want to run any part at the very edge of its performance range. 330 sounds more realistic even if the mapper could squeeze more out of it.
Info on injector power ratings here:
Scoobypedia | Trusted knowledge for everything Subaru | Knowledge / Estimated Horse Power from Injectors

 

I think you only need 2% of headroom on modern-day injectors i.e. IDC at 98%, as the variance of flow is across all 4 injectors is appreciably less than 2%

So with that in mind, then theoretically:-

440 x 3.5/3 x 98/100 = 503cc.

So lets say they'll be running at 500cc at that 98% IDC.

Which is pretty much bang in the middle of 440s and 550s so, according to that guide, they should be good for 360+ bhp (if you take the average of their respective lowest figures i.e. 320+400 / 2).

 

I'm not sure what you are trying to do with your maths there, but lets not confuse the guy, fuel flow is NOT proportional to fuel pressure so you cannot expect 3.5/3 times the fuel delivery.

Roughly speaking you need 4 times the fuel pressure for twice the fuel delivery.

 

Ah, fair enough. I didn't realise that.

Okay, so as said, 440s probably are marginal for 350 then.

(My maths would've been sound... if my theory wasn't bollocks )

 

Yep its a funny one. Raising the fuel pressure doesn't really give you much headroom as a result but it should allow for 330hp with a small margin rather than running them flat out.

 

Sure, sure.

 

right, mapping was today, results not what i was expecting but it drives very nice on the road,
power was:
310.2bhp@6115rpm
234.7bhp at the wheels

torque was 380nm@4750rpm

boost was peaking at 20psi dropping of to and holding 16-17psi,

during the mapping we had a quick feel of the boost pipes and these were so hot you could barely touch them, so im guessing a little work is needed to keep things cooler and in turn maybe a few more bhp,also maybe a boost controller to try to hold the 20psi,
any opinions on these results?

 

If you're not used to Nm, then that equates to bang on 280lb ft which is what you'd expect when producing 310-odd on the TD05.

I would have thought you'd have got nearer 330-340 as I mentioned earlier, but hey ho, engines vary and all that. Was it the injectors that were the limiting factor, or the concern of the temp of the charged air?

Still, as you hit upon, numbers are one thing, but more importantly, it's how it drives that matters. I assume you're very happy with the latter aspect?

 

the early car is so fickle.. the exact same spec and it will vary by a reasonable amount yet sometimes unbelieveable figures.. the top entry TD05 16g is unlikely to make 350 like it will when converted to front entry.. 310bhp and 280lb is bang on..

Assumnig the car was mapped on the dyno then the heat in the intercooler pipes will be higher due to heat soak.. tyake it for a spin and check the intercooler pipes.. you might find they are fine.

Simon

 

So that top entry bend - plus the other 90deg bend of the turbo intake hose - really are restrictive then. Mind you, you can see why...

So Simon, if people want to fit a front entry turbo replacement to their MY93-96 car, then it REALLY is advisable to keep it front entry by going to the hassle of going under the IM? Do you need the Carl Davey/RCM IM spacers, plus relocate the power steerring header tank, to do this?

 

for the sake of 10~15bhp it is possibly not worth the hassle for most.

Simon

 

injectors where not a factor, managed to get a set of 550s in there before mapping, i did as jolly green monster said and took it for a spin, turbo to fmic pipe was same as on the rollers, fmic to tb slightly cooler, i have no heatsheild on the turbo nor is the downpipe wrapped so i was expecting a bit of heat but not quite as much as its producing, also before the mapping session i noticed a slight rattle sound, i thought at the time maybe it was just my manifold heat sheild, but after the mapping on the way home it got slightly louder, got it home and turns out the joint between turbo/uppipe is blowing, would this have a big effect on the figures?i did notice that the turbo is spooling quite late, full boost by around 4600-4700rpm?
over the next few weeks il be wrapping all intercooler pipes and downpipe and sort out the blow and get it booked in for a check over on the rollers.

 

had another look over the impreza today to try and cure the blow, as i mentioned in the previous post i said i could hear a rattle, and it was just that, found out that the wastegate did not have enough pre-load on it and the penny valve was rattling around, wound it in a turn and sorted,builds boost a bit quicker, then the cel light flashed! appears my maf is nearly maxed out, my mapper did mention that it was quite close to its limit but said there was proberbly another 30-40bhp to go before it was going to be an issue, ive had a search and it looks as tho my maf should be good for around the 350bhp mark? if so why am i seeing the cel light for it at only 310bhp?