marklemac

Hi,

I currently run a STi7 with PPP. The PPP certainly transforms the current STi into a good car, but it does feel like it needs some more ooomph.

So, assuming I wanted to keep my current investment in the PPP, and assuming I didn't care about the warranty, what options do I have ?

Are there any more exhaust mods that can be done ?

Can the boost be increased ? (will the modified PPP-Ecutek'd ecu cope with extra boost)

Can a Dawes device be fitted ?

Air filter ?

Is there any way of getting the power/torque up from Prodrive's 300/299 to say 330/330 ?

THANKS.

Callum Ferguson

iTrader: (1)

Hi Mark,

How much more do you want? - a little or a lot

Has your fuel pump been upgraded as part of the PPP?

There may be a problem with the existing FPR when looking for more than PPP offers. I have it from a good source that the OEM FPR has an outlet size which will have difficulty flowing enough fuel for my current requirements and he was not trying to sell me a new FPR...

Roger Clark Motorsport offer a K&N induction kit for the STi 7 which gives nice sounds and hopefully more air - appropriate remapping may be required though.

My car definitely went much better after a Milltek, K&N & Ecutek were done.

Lots of good bits becoming available once you start looking but it is best to have a plan I didn't and it gets expensive.

regards,
Callum

Pete Croney

Mark

You can use the PPP backbox, centre section and fuel pump, but the rest of it has to be changed to get more.

Fitting a downpipe and getting an independant EcuTek installer to remap your ECU will give you 330bhp+.

MikeWood

In our testing we found that removing the catalyst in our downpipe actually reduced performance, not improved it!

Mike

marklemac

Mike,

Just the man to respond.

I am very pleased with the PPP, but the car does still seem underpowered and feels like there is more potential in there.

Will/Are Prodrive going to offer any other power enhancements. Isn't your prodrive live car running more power ?

Maybe Prodrive might offer a stage2, but this might not retain the full Subaru warranty, but customers would feel happy with your knowledge of the tuning world and still go for it...

What do you think Mike ?

Pete Croney

Care to show us the test regime and results Mike?

I would be VERY interested in this one

Floyd

iTrader: (9)

Mike, is this the std DP and cat or your own special DP with cat?

I did read a post from you before saying that you achieved the best results with a cat in place but IIRC it was your Prodrive version.

I would guess that if Prodrive could have given more power safely and within warranty cliams considerations, then they would have done.

F

MikeWood

There are no plans at the moment to either alter the specification of the STi performance package or introduce something that has more power. We feel that at the moment the engine is running safely at this output and to increase it further may lead to reliability compromises. We are fully aware that some tuners are claiming higher outputs but they don't have the same warranty implications, namely there isn't any

Pete
Early on in our testing we used a catless downpipe as we felt this would be the best/worse case scenario that the engine would see and mapping it to give safe boost levels would cover us for most circumstances. This was borne out by the fitment of our first catalyst spec which saw a slight reduction in boost levels. After testing several other catalysts and different ways of integrating them into the downpipe we found that we had actually picked up boost from the catless downpipe (note this wasn't as a result of any wastegate restriction). When you realise that the surface area of the cat is 4x the cross-sectional area of the pipes either side and our inlet and outlet cone designs are making sure the flow utilises all that surface area, then the fact that flow isn't restricted in anyway is not unexpected.

Mike

Pete Croney

Mike that is true, but all tuners are acutely aware of the implications of pushing customers cars to the point of them blowing up and all that I know of map cautiously, just not as cautiously as what Subaru UK restrict your company to.

With regard to the cat, this flies in the face of all logic and experience. Whilst the cat you are using may be quite free flowing, it will not be as free flowing as having no cat at all and it will not create more boost. Would 2 cats work even better? In the light of these results are you thinking of fitting a downpipe cat to the WRC car?

As ever...

MikeWood

Pete

It may not actually the cat itself that's affecting the efficiency. The cat we are using flows at least 3x as much as the pipes either side so it can't cause any restriction as the relative flow rate is lower.

What's more likely to be having a positive influence is the fact that there is a relatively large volume in the cat and the inlet and outlet cones that gives the effect of an open pipe.

Mike

Pete Croney

If the cones are a good size I can see the logic in that Mike

MikeWood

Can't be right. PC following my logic!!

Pete Croney

When you said it made it behave like an open pipe, it all became clear

MikeWood

Think we may just be starting a new area of exhaust development???

Mike

Floyd

iTrader: (9)

I know a car that has the std DP but with the cat removed, leaving just the cavity. It spools up very quickly and feels quite torquey but I always thought that the cavity would produce a restriction. Perhaps the extra space/volume just after the turbo is aiding gas flow somehow?

Mike, does your DP with cat have an open neck or closed neck design?

F

Jza

So Pete - how about developing a nice wide open cat'd D/P so that we can all pass our emissions AND get better performance....

Now that would surely sell????

Jza

PS LOL Mike and Pete agree on something (Just don't mention the air filters )

Pete Croney

Jza

We actually agree on quite a lot of things and have been friends for years. We only argue for your entertainment

Pete Croney

Oh... and that's why you keep your old centre section

MikeWood

Jza

That's what we've done.



Pete

That's what you think!!!
I couldn't possibly comment......


Mike

Jza

LOL guys

Jza

ARRON BIRD

Sounds like a load of tosh to me

Floyd

iTrader: (9)

So for even better performance, have the cavity but lose the cat as well?

F

marklemac

Thought I'd bring this topic back up.

Just had a flyer through the post from Mitsubishi (I used to own an Evo 6) with the specs of the FQ-330. (with 3 yr warranty)

Is there any likely chance that a revised PPP-330 may come out ? Or will Subaru/Prodrive just accept that the 300bhp PPP is enough ?

Moving on from this, Pete commented that I could keep my fuel pump, back box and decat centre section, and then go for a ecutek to get their 340bhp package.

Is this a realistic power upgrade ?

I see TSL are now advertising 333/333 conversions...

Bob Rawle

This made a good read, picking up on the discussion about boost levels and the effect a cat may or may not have, its not about boost but about air flow, pressure compresses air so increasing mass flow however its possible to have pressure and no flow in the extreme, so increased pressure could just mean more restriction not less.... so how would that fit into the arguement ?

As a stimulus to anyone ?

bob

Apple

Bob, this is taken from a Lotus site but may give an insight... (sorry if it's teaching your grandmother to suck eggs

"The first 50 SVA Elise Sports 160's had the motorsport catalyst fitted. The external appearance of this catalyst is very different. The standard catalyst housing is made from two clams welded together to form a flattened oval casing. The motorsport catalyst is in a short cylindrical casing. The difference between them is the density of catalytic materials and the surface area of catalyst exposed to gas flow. The motorsport catalyst has a lower density, less surface area, and is hence less restriction to air flow. The difference in power between a motorsport catalyst and a bypass pipe is only about 2-3 PS. The former costs about £900 and the latter about £50."

From this, the shape of the cat is important - expanding the gas across a section on entry to the cat and compressing it across another section on exit means that in the case of a "flattened" cat, some air velocities will be different to others next to the internal walls and hence there will be a greater chance of flow disruption due to turbulence.

If a cylindrical cat pipe is used, the gas expands and compresses at constant rates so there are less velocity differences and hopefully less turbulent flow.

Secondly, the way the catalytic elements are layed out will have an effect on the flow rates - high density will have a larger surface area for chemical interactions but will also create more flow restriction. Taken to it's extreme, a too tightly packed cat will choke the system. A more open structure will allow more flow through but will have a smaller surface area which in turn reduces the effectiveness of the catalyst if taken too far.

The openness of the structure will also dictate the amount of "straighening" to the air as it passes through - a compromise is needed (as ever) between flow rate, catalyst effectiveness, turbulence, cost, available space etc. A lower turbulence flow will travel faster than a swirling one down a pipe.

The Lotus website also mentions about a vibration / noise fix being available - I suppose this is what some manufacturers do by putting ribs across the cat body for strength / alter the natural frequency of the housing. These ribs, depending upon where they are in the gas flow, may affect flow performance as well...

As for boost, as you say, it's not related as we're dealing with the turbine side with the exception that the amount of backpressure on the turbine side will affect the spool-up rate of the compressor side (the turbocharger matching "may" be tweaked to take this into consideration.)

All IMO, and I'm prepared to be corrected

Apple

[Edited by Apple - 12/20/2003 10:14:07 PM]