Anders_WR1

iTrader: (8)

Mike,

Having owned my WR1 for over a year, I'm looking for a bit more power.

I read a post on here where you said the VF35 turbo is already being pushed hard and that any further increase in power would push it out of its 'efficiency envelope'. I think I understand what you were saying - the turbo is capable of producing more boost, but the charge air temperature would rise with more chance of Det and reduced reliability as a result.

Having trawled through many web sites, I found a company that offers an upgrade to 350bhp while still using the OEM turbo. They do a special reduced cost package for STI owners that already have a PPP fitted. Their kit comprises:

High Flow Cold Air Induction Kit
Larger TMIC
Re-map

It seems they get around the increased charge air temps by fitting a larger TMIC. Can't Prodrive investigate a similar upgrade? I don't want to void my warranty, but at the same time, it's frustrating when many Third Party company's offer solutions for more power.

On a related note, now that Tesco are gradually releasing 99RON at their garages, could Prodrive program the re-map have a dual-map for 97 and 99 RON? The WR1 seems to pull smoother on this stuff with the standard map, so I'm sure bigger improvements could be had in conjunction with the above upgrades.

One last note. I asked my dealer if I could fit Samco hoses to dress up my engine bay. They said Subaru wouldn't be happy with this, as they claimed the hoses may note be made to the same specification as the OEM ones. You and I both know the Samco's are a higher spec - so why don't Prodrive test them, authorise them and sell them as an upgrade?

Thanks in advance.

Anders

PS I haven't mentioned the company's name, as I don't want this to seem like an advert for them. If you don't know who it is, PM for the details.

jasonius

iTrader: (1)

Intersting.. I thought that the latest STI TMIC was very efficient, just how much better would an aftermarket unit be..? This is why the usual route after the STI TMIC is a front mount.

Just a thought..

Anders_WR1

iTrader: (8)

They use an APS TMIC which has a volume 2.6 times larger than the STI unit. Not sure what its flow characteristics are like, but it must do the job.

They do another upgrade to 360bhp which uses the APS DR 725 FMIC, upgraded Walbro fuel pump and 3.5" exhaust system, but it costs another £2,400 over the 350 package. It seems mad that you need all the extra kit to extract an extra 10hp!

GrollySTI

I believe you are talking about WRC Technologies.

I've been looking at the 350 upgrade also, but I'm not convinced of the benefts.There does seem to be a discrepancy between the claimed output of 350 and the dyno graph which shows 337 (I think).My car is an STI with PPP but I have had a TEK3 remap which gave me a dyno'd 311bhp (as against 280 with the PPP only)

I had this done at powerstation which I understand as being one of the more conservative rolling roads.I suspect therefore that the addition of a cold air intake and new top mount may not be good value for money in the bhp/£ stakes for me.

It also seems odd that the next package up only gives a reported 10bhp gain but includes some meaty performance parts.

All IMHO of course

MikeWood

Anders

In our experience there's no benefit in replacing the intercooler as the STi is as efficient as you'll get in the space available. Increasing volume will also slightly increase lag which is not a desirable thing.

As you state, the turbo is pretty close to the limit as it is on the WR1 but there may be ways of opening up the envelope slightly and we are investigating doing just that at the moment. Moving the airfilter to a 'wet' area will not be one of the things we do though!

Ref the Samco hoses, as there will be no performance increase by changing them and lots of other people are already selling them, we won't be producing a 'me too' product. The only way we would do it is if we could provide a quantifiable benefit and brand it solely with Prodrive logos, neither of which are going to happen with a generic Samco product. I think you can also understand why we wouldn't be testing and approving a product to then not make any money by selling it.....

Regards

Mike

Anders_WR1

iTrader: (8)

Mike, cheers for the reply.

Now you have us all thinking...Hybrid turbo, Water Injection, revised turbo inlet pipework, fuel pump, injectors, re-map for 99RON...

If there's a spare output on the ECU, it would be great to auto-spray the Intercooler when your pushing hard as part of this upgrade. At the moment, any benifit you get from the spray being activated is wiped out by the sloppy gear changes and one-handed driving while you press and hold the button in! I think it was auto-sprayed on some of the older STI's, not sure why this changed.

I know your dreading this question, but when can we expect the upgrade to be released < 6 months or > 6 months?

Regards

Anders

john banks

Hybrid turbo - ball bearing unit will make little difference, the VF35 can surge already if pulled in too hard, twin scroll is not going to be cheap, so basically you are looking at moving your power band up the revs and making the car less driveable. Some more normal people and even enthusiasts prefer TD04s on their 2.0 litre cars for this reason. No free lunch. Prodrive do well considered warranty friendly upgrades that enhance driveability.

Water Injection - tricky since the gains are small and there would need to be all sorts of contingencies to actually run with the gains since system failure will otherwise result in engine failure if you are tuned for gains.

Revised turbo inlet pipework - the stock inlet pipe is not really the restriction at this level. Even on more restrictive standard inlet pipes on the GC8 you can pull 400 BHP of air through them.

Fuel pump - no need on the stock turbo.

Injectors - ditto

Re-map for 99RON - I doubt there is much point since the existing map is likely to be able to run a bit more ignition especially in heatsoaked unfavourable circumstances even if it runs IAM 16 in less stressed use.

Prodrive as usual manage to fit sensible mods that add resale value, are well engineered, fit properly, don't break, don't sound like a WW2 bomber, don't need gauges, don't cause lag and keep the warranty.

Looney modifiers such as myself more than double the power output of their cars and have to remember things like response, refinement and overall ownership ease only as distant memories Less is often more etc...

john banks

Unless I buy another marque (which new are usually overpriced in comparison to Subaru offerings or are in poor condition and overpriced used), I'll most likely end up with a Euro/UK 2.5 STI. I'm seriously considering just Prodrive style exhaust mods (ie quiet and emissions friendly) and a remap. Whether I buy this from Prodrive or do my own will remain to be seen, if the Prodrive kit is up to the usual standards there is no point wasting my time mapping it. Although it is ironic that I only got into tuning because my original PPP overboosted and the dealer couldn't sort it

mgcvk

Wouldn't just a decat and remap get you around 20hp even on a WR1. Combined with a TD0518g/20g a lot more.

john banks

The Prodrive sports cat is apparently no more restrictive than a decat. 18 and 20G have more lag than a VF35.

Anders_WR1

iTrader: (8)

John, granted the fuel system may not need upgrading further if using the standard turbo, but it sounds like Mike thinks a bit more can be tweaked out of the standard turbo.

When I mentioned the revised turbo intake pipework, I wasn't suggesting the current set up is restrictive; rather that the new pipework could feed the turbo less turbulant air or something. If a 747 plane has problems with turbulent air when landing, surely turbo blades spinning at 100,000 rpm would benefit from a streamlined flow of air?

Anders_WR1

iTrader: (8)

Mike, forgot to add uprated oil cooler to the wish list. My oil temps regulary reach mid 120's when I take my car back to the Isle of Man. Perhaps this is low relative to track use? - I don't track my car, so don't know what oil temps are reached in that environment.

john banks

Surely if it was turbulent it would also be restrictive? You have lots of preparation of the airflow before the MAF sensor.

gussy

iTrader: (2)

Just my 10 pence worth mike I have heard on the grape-vine that prodrive are looking at a more aggressive/track related map above their ppp is that correct?

Anders_WR1

iTrader: (8)

There my be lots of preparation of air flow before the MAF sensor, but the hose that leads from the MAF to the turbo inlet look as aerodynamic as a Lada Riva Estate! The hose almost goes through a 90 degree bend. Surely replacing this with a silicon hose and flow forming the pipe will yield some sort of increased efficiency on the turbo compressor wheel? So I agree the air would be turbulant and more restrictive on the standard STI turbo pipe.

Would be interesting to see how a turbo sucks the air in through a silicon hose. ie does the air start to create a tornado effect in the pipe before it enters the turbo. Would there be any advantages in shaping the silicon hose to start the air rotating before it hits the compressor wheel?

john banks

If it is restrictive, then changing this section would yield more power, and you would have an excessive drop in pressure along the restrictive section when you measure with a manometer. Whilst it looks horrible, the standard item does fit well and the cross sectional area through its bends is far better than the old GC8 one that as I say does seem to manage 400 BHP. In fact changing it on the GC8 can make one of the more popular 400 BHP turbos have nasty compressor surge, it would seem that the intake air velocity might be too low? Or perhaps the better flowing inlet pipe gives a higher absolute pressure at the compressor inlet which in turn produces more exhaust gas and you cross the surge line more easily?

When you consider what a turbo inlet restrictor can flow it puts things into perspective about inlet restrictions? I've done the whole lot through to a 100mm inlet pipe straight onto the turbo with no bends and no pipes entering or leaving. Changes on the inlet have been disappointing compared with the hype.

The big restriction to the exhaust is the turbine wheel, and the compressor wheel's flow is the big limitation on inducted mass air. Changing these will make more lag generally, which no 2.0 Scooby needs any more of as they are quite bad already.

Anders_WR1

iTrader: (8)

I understand what your saying - the current setup should flow well enough to get 400 bhp, but is that with a VF35 turbo? All I was suggesting is that given the VF35 is being pushed hard already in the WR1, any slight improvement on the turbo induction side may help with the turbo's 'efficiency evelope' as Mike puts it.

If you were working for Prodrive, how would you try and expand the VF35's efficiency evelope?

Can you also explain what a turbo's surge line is. I'm interested in knowing what happens in these engines, as well as thrashing them out on the road.

Do you think the STI air oil cooler would be a good idea for my car, given the oil temps that are being reached? I think the Oz STI's have this air to oil cooler fitted as standard.

JIM THEO

I have a WRX MY03 with AVO turbo inlet hose (from MAF directly to turbo), STI I/C and hoses, Scoobysport up-down pipes, factory center section/back box and US STI fuel pump, no turbo mods at all.
What I have found is that turbo inlet hose gives more lag at this level of performance while adds some more HP's at middle-high rpms.
Although in a friend's STI with TSL 333 the same hose gave 150-200 rpms lower spool up witch means the standard air hose is perfect for about 300-320ps and the small TD04.
The STI I/C adds slightly in performance and gives BETTER spool up at least in my car contrary to what other people believe, it "sent" me back to the same spool up point after the AVO inlet!
So bear in mind each part behaves differently in different cars/setups...
JIM

john banks

"I understand what your saying - the current setup should flow well enough to get 400 bhp, but is that with a VF35 turbo? All I was suggesting is that given the VF35 is being pushed hard already in the WR1, any slight improvement on the turbo induction side may help with the turbo's 'efficiency evelope' as Mike puts it."

Certainly not on the VF35. IMHO, the VF35 is the big bottleneck, not anything else. But changing it (unless you go twin scroll) will always move the power band upwards and reduce response.

"If you were working for Prodrive, how would you try and expand the VF35's efficiency evelope?"

I wouldn't as it is near enough already. Keep it reliable.

"Can you also explain what a turbo's surge line is. I'm interested in knowing what happens in these engines, as well as thrashing them out on the road."

The compressor wheel will surge when the point at which it is operating on its compressor map (which is flow vs pressure ratio) comes too far left over the surge line - ie too high pressure ratio without enough flow. There are lots of webpages on compressor maps and surge.

"Do you think the STI air oil cooler would be a good idea for my car, given the oil temps that are being reached? I think the Oz STI's have this air to oil cooler fitted as standard."

I've reduced my oil temperatures by improving water cooling, but my setup that reaches 110 after 5 laps of a track or reasonably hard road use is borderline IMHO. Whilst the oil may handle a lot higher without breaking down and whilst maintaining oil pressure, Subarus are not without their big end bearing problems.

supa

iTrader: (5)

nice read

Anders_WR1

iTrader: (8)

That was a blast from the past! Now running an MD321H turbo @ 402bhp

Anders