Aiming for 300-330bhp

[Mr_White]

Hi there, sorry for all my threads lately, but I have a lot of new things to learn now that I've got my hands on one, opposed to just looking at them ;)

I'm planning on fitting a full de-cat exhaust system from Hayward & Scott, up pipe, down pipe, centre pipe, and back box.

It's a V2 STi, so it's supposed to be 280bhp.

What would be required to get it to 300-330bhp?

The exhaust system and a remap, maybe an induction kit or would an uprated panel filter still be better? (does the V2 have MA problems with an induction kit?) and new fuel pump should get it to 305-310bhp easily, shouldn't it?

What do you think would be needed to get it to 330bhp, if it's not capable with the above.

Thanks

[Kit]

You'll need a bigger turbo for a reliable 330bhp, something like a TD05 16G/20G or a VF34 I think. Your also starting to get near the max of stock injectors so an upgrade to 440/550cc is advisable, a front mount intercooler, fuel reg and a set of uprated spark plugs would also be a good idea if you dont already have them and then a remap once they've been fitted.

It's important not to run an engine once you've upgraded the injectors until it's been remapped, since your ecu might still be chucking in fuel thinking they are 330cc standard items which means you run the risk of bore wash.

Basically it's not cheap to go over 300 bhp properly, of course you could just turn up the boost and hope your turbo can take it.

[wrx]

The V2 Sti should have a TD05 as standard.

It should run upto about 320 at around 1.4 - 1.5 bar.

They run very hot over 1 bar so best not to push it.

[Mr_White]

I think I'll just aim for 300bhp for now then, and maybe make the jump to 330-350 later, since it sounds like I'm going to need new injectors and maybe an FMIC, that's not cheap, and there's no point fitting parts one at a time, might as well just buy them all at once, get them fitted and remapped.

What would I need for 300bhp then?

De-cat up pipe, de-cat down pipe, de-cat centre pipe, back box, an induction kit or uprated panel filter, an uprated fuel pump, uprated spark plugs, maybe a fuel pressure regulator, a remap.

That sound about right, or have I missed something?

[Kit]

you don't need a fuel reg until you upgrade the injectors really

[WhiteRAman]

I think I'll just aim for 300bhp for now then, and maybe make the jump to 330-350 later, since it sounds like I'm going to need new injectors and maybe an FMIC, that's not cheap, and there's no point fitting parts one at a time, might as well just buy them all at once, get them fitted and remapped.

What would I need for 300bhp then?

De-cat up pipe, de-cat down pipe, de-cat centre pipe, back box, an induction kit or uprated panel filter, an uprated fuel pump, uprated spark plugs, maybe a fuel pressure regulator, a remap.

That sound about right, or have I missed something?

You will pretty well need all of these things.

There is only one cat on a classic Impreza and that is in the d-pipe, all the other lookalikes are flame trap/resonator boxes.
Remove the OE manifolds and port/wrap them and at the same time fit your new up-pipe.
FMIC's are not expensive these days so go for one now.
An adjustable FPR is needed at this stage as the original 380 injectors will be running at max but with the uprated pump and FPR you can get them near to 440 capacity.
Some sort of electronic boost controller.
Make sure the exhaust is 3" all the way.

Needs to be tied together with a rolling road set up for the boost/FPR adjustments.

[Mr_White]

Walbro in-tank high pressure fuel pump kit: £94

Fuelab fuel pressure regulator: £205

NGK PFR7B Spark plugs (4): £51

Pipercross panel filter: £33

Apexi AVCR boost controller: £329

Remap: Need to find out what chip it has

H&S de-cat up pipe: £123

H&S de-cat down pipe: £193

H&S de-cat centre pipe: £94

H&S angled back box: £233

How much does porting and wrapping the stock manifolds usually cost?

And will the stock injectors be ok running at 300bhp with a fuel pressure regulator?

I didn't think an extra 20bhp would be this expensive :grin:

Although the improved response and the in-gear adjustments from the boost controller will be good.

What do you think the estimated hours of labour would be on that? I plan on getting it done at Zen Performance who charge £50 an hour.

[Kit]

How much does porting and wrapping the stock manifolds usually cost?

Free, you can do it yourself.

And will the stock injectors be ok running at 300bhp with a fuel pressure regulator?Yep

I didn't think an extra 20bhp would be this expensive :grin:Anything done properly usually costs and arm and a leg. You'll find your engine isn't producing 280bhp anymore, more like 250-260 but with a remap and those mods your impreza should sit comfortably at 300bhp.

Although the improved response and the in-gear adjustments from the boost controller will be good.

What do you think the estimated hours of labour would be on that? I plan on getting it done at Zen Performance who charge £50 an hour.Impossible to say, call Zen and ask them. At a guess i'd say your looking at... 250.

I would say getting a good aftermarket ecu would be a better idea than a Apexi AVCR boost controller, imho. Also think about doing the mods yourself if it isn't your daily drive, it isn't actually as hard as you may think.

[Mr_White]

Free, you can do it yourself.

Won't I need a access to a ramp or lift to get them out properly?

I think throwing money at it will be easier :mrgreen:


Anything done properly usually costs and arm and a leg

True ;)

Impossible to say, call Zen and ask them. At a guess i'd say your looking at... 250.Not too bad then, I'll be happy with 250-350.

I would say getting a good aftermarket ecu would be a better idea than a Apexi AVCR boost controller, imho.How much would that cost? I know that you need to take away boost control from the stock ECU, would the AVCR not be the cheapest way?

I don't think I'll need any of the features of an aftermarket ECU, will I?

It should already have a piggy back chip of some kind.

The car is a daily drive used for work, so it can't really be off the road apart from a weekend at a time.

Otherwise I'd do most of it if I had a ramp and the right tools.

[Kit]

An AVCR will be the cheapest, but for instance a SimTek ECU means you don't need a MAF sensor anymore plus you can store two maps for different driving or fuel octanes.

Well only you know what you need, besides you can always sell the boost controller at a later date if you decide you want an aftermarket ecu.

One of the last things I would like to do is upgrade from my Simtek to a Motec M800, but that's pie in the sky...

[WhiteRAman]

Walbro in-tank high pressure fuel pump kit: £94

Fuelab fuel pressure regulator: £205

NGK PFR7B Spark plugs (4): £51

Pipercross panel filter: £33

Apexi AVCR boost controller: £329

Remap: Need to find out what chip it has

H&S de-cat up pipe: £123

H&S de-cat down pipe: £193

H&S de-cat centre pipe: £94

H&S angled back box: £233

How much does porting and wrapping the stock manifolds usually cost?

And will the stock injectors be ok running at 300bhp with a fuel pressure regulator?

I didn't think an extra 20bhp would be this expensive :grin:

Although the improved response and the in-gear adjustments from the boost controller will be good.

What do you think the estimated hours of labour would be on that? I plan on getting it done at Zen Performance who charge £50 an hour.

I can supply most of the parts as listed above (either same brand, similar spec or BETTER spec) than you have been quoted.

Personally I would estimate a fair bit more than 250-350 for labour.

Plugs..................................1hour
FPR.........................at least 2 hours
Pump..................................1 hour
d-pipe and system.................2 hour plus extras like broken/siezed studs etc
up-pipe................................1.5 - 2hours
Boost controller fitting and set up approx 2-3 hours
Mapping time extra, normally remaps are around the £25- £350 mark on their own but this is all dependant on what ECU/chip/board you have fitted anyway.

This is a fairly accurate "guesstimate" as to the times involved but I will not be far out so at least you wont get a huge shock.


Give me a call on 020 8373 7336

Ralph
Milsport

[Mr_White]

Thanks for the info, the labour estimates are helpful.

I'll probably give you a call closer to buying it all ;)

[Mr_White]

Does anyone run this backbox, or know anyone that does?

http://www.haywardandscott.com/Details.asp?ProdID=153&category=13

I'm not a huge fan of cannon exhausts, and I'd much rather keep the standard look, but I'm not sure what the power restrictions would be since it's dual exit, or will it not make much difference?

Cheers

[WhiteRAman]

TBH and IMO that back box would do absolutely nothing for the car apart from looking nice and shiny and even then the welding looks to be pretty rough.
It looks to have a standard size pipe into the rear of the box and the twin "pea shooters" look to be fairly small as well.

The whole idea of exhaust tuning is to get the burnt gasses out of the engine and away from the car as quickly as possible. With the sharp bend into the silencer, the small diameter (therefore restrictive) main tubing and the small diameter exits this cannot happen.
When companies like HKS and Blitz originally designed the "cannon exhausts" back in the 90's it was for a reason, they are still the most popular style because they actually work.
To press home this point even more, remember the prodrive stainless steel back box on the P1 ? or even the single exit rear box as found on the STi's ? both of these were slightly less restrictive than the twin pea shooter design but were still 10-12 hp down on a good 3" inlet, 4.5" exit rear box.

If this is what you are considering then save youself the money, (£340 delivered:shock::shock:) and stick to the standard set up, the only people to benefit will be H&S.

[Kit]

Does anyone run this backbox, or know anyone that does?

http://www.haywardandscott.com/Details.asp?ProdID=153&category=13

I'm not a huge fan of cannon exhausts, and I'd much rather keep the standard look, but I'm not sure what the power restrictions would be since it's dual exit, or will it not make much difference?

Cheers

I wonder how many of those they have sold LOL!

There are loads of other tail pipe designs to look at besides the big exit exhausts, the oval designs look quite nice on classics imho.

Like Ralph says though, the most important factor to decide which route you go for, when trying to gain power, are the restrictions in the design.... and that twin exit has lots of them.

[Mr_White]

Fair enough, I'll stick with the jap angled exhaust ;)

Cheers.

I wasn't sure whether it'd just be a 2-3bhp difference for example, or a lot more, and from what you've said, it's the latter.

The twin exit would have been nice to keep the stock appearance, and maybe the stock sound, whilst taking the power up, the car has been stock for 13 years, with 27k miles on it, I felt it'd be a shame to stick another big generic exhaust on it, but like you say, Ralph, they're designed like that for a reason.

Thanks for the advice.

Just another quick question, a bit of a stupid one that I think I already know the answer to, but I might as well check if I'm going to do all of this properly ;)

As long as the rest of the system (up pipe, down pipe, centre pipe) gives the most straightforward route with the least restrictions for the gasses, does it matter what backbox is on the end of it, as long as it's a good one, of course.

Or are some backboxes designed to flow better whilst working with certain design quirks in the design (to maybe increase pressure etc) of the centre pipe or down pipe to go with it, etc.

Since I'm not sure if the sound from the H&S is really my favourite.

I'm guessing it doesn't matter, but I'd rather ask a stupid question than look clever and take a gamble ;)

[Kit]

Fair enough, I'll stick with the jap angled exhaust ;)

Cheers.

I wasn't sure whether it'd just be a 2-3bhp difference for example, or a lot more, and from what you've said, it's the latter.

The twin exit would have been nice to keep the stock appearance, and maybe the stock sound, whilst taking the power up, the car has been stock for 13 years, with 27k miles on it, I felt it'd be a shame to stick another big generic exhaust on it, but like you say, Ralph, they're designed like that for a reason.

Thanks for the advice.

Just another quick question, a bit of a stupid one that I think I already know the answer to, but I might as well check if I'm going to do all of this properly ;)

As long as the rest of the system (up pipe, down pipe, centre pipe) gives the most straightforward route with the least restrictions for the gasses, does it matter what backbox is on the end of it, as long as it's a good one, of course.

Or are some backboxes designed to flow better whilst working with certain design quirks in the design (to maybe increase pressure etc) of the centre pipe or down pipe to go with it, etc.

Since I'm not sure if the sound from the H&S is really my favourite.

I'm guessing it doesn't matter, but I'd rather ask a stupid question than look clever and take a gamble ;)

I'm not exactly sure what you're asking :confused:

Do you mean:
-Which is the most efficient tail pipe design? the least restrictive which would be a 4"+ from a good make
-Which is the most efficient exhaust? I suppose a short side exit is the best.
-Does it matter which back box I use? yes because if you have a twin exit design like previously mentioned it will cause extra back pressure, also if the back-box has angled small bore pipework before the tail pipe then it will cause further back pressure issues.

Creating pressure in a turbocharged cars exhaust system, has no positive side effects that I can think of.

It might sound silly, but go to a impreza club meet and just listen to peoples exhaust notes, also if you get different aftermarket headers it will change the way the exhaust sounds.

[Mr_White]

I mean does it matter what back box I use, as long as the rest of the system is as free flowing as possible, and as long as the back box isn't restrictive as well.

For example: H&S de-cat up pipe, down pipe, and centre pipe and a Blitz Nur spec backbox, or are back boxes generally designed (pipe work inside the back box etc) to work in-conjuction with design quirks in their associated centre pipe/down pipe.

I'm guessing there is no difference as long as the back box isn't inherently restrictive.

I said it was a stupid question :D

But it's always best to check first ;), since a lot of the big name back boxes usually offer at least a centre pipe and sometimes a down pipe to go with that particular model of back box, so it wouldn't be out of the realms of possibility that they might be designed to work at their best together, and might suffer if you mix and match.

I hope that makes it a bit clearer :mrgreen:

It's not important though, I'll probably just go with the H&S.

[WhiteRAman]

Basically you have answered the question yourself.
A system is designed from the beginning to the end with flow benches to get the best from each component and to make sure that it all works together as efficiently as it possibly can.
Mixing and matching will not make for the most efficient system.

Personally I cannot understand (although it is your car and you can therefore do what you like) why you are so struck with the H&S set up.
When compared to most of the other systems available it is certainly not the most powerful, is poorly finished, does not have the nicest (or quietest) sound and is generally bloody expensive for the quality you are getting.

If it helps you make your decision a bit easier:

When I 1st started buying and tuning Imprezas back in the 90's the choices we had were very limited, companies like Blitz and HKS exsisted in Japan but getting their parts to the UK was very expensive.
A bloke called Pete Croney who also wanted more from his Impreza went to H&S and got them to build a one off exhaust for his car, he got an awful lot of enquiries about where he got it so he went back to H&S and struck a deal with them that they would make the system and he would market and sell them with sole rights........................that was the beginning of Scoobysport who have since folded, H&S then took over the rights.
Since those early days (when 95% of tuned Imprezas had Scoobysport exhausts, because that was all you could get) almost every car I ever knew has since had that system removed and replaced, WHY?, because they are not the best.

I am sure you will make the correct decision (as far as you are concerned), just trying to steer you in the right direction and stop you making a costly mistake.

[Kit]

For example: H&S de-cat up pipe, down pipe, and centre pipe and a Blitz Nur spec backbox, or are back boxes generally designed (pipe work inside the back box etc) to work in-conjuction with design quirks in their associated centre pipe/down pipe.

I'm guessing there is no difference as long as the back box isn't inherently restrictive.

I said it was a stupid question :D

But it's always best to check first ;), since a lot of the big name back boxes usually offer at least a centre pipe and sometimes a down pipe to go with that particular model of back box, so it wouldn't be out of the realms of possibility that they might be designed to work at their best together, and might suffer if you mix and match.


Don't mix and match, buy an entire system from one brand/manufacturer to avoid compatibility issues and I don't know anyone or have read about anyone (in PJC, Banzai..etc) that runs a H&S exhaust, I don't really understand why you are so smitten with them?

TBH I didn't even know who H&S were until this thread came about, apart from a system which is for sale on scoobynet.

[WhiteRAman]

I don't know anyone or have read about anyone (in PJC, Banzai..etc) that runs a H&S exhaust, I don't really understand why you are so smitten with them?



My point exactly, they are old school technology that was surpassed years ago.
I am now bowing out of this thread.............................gracefully!!

[Mr_White]

I had just read a lot of good things about them and they seemed quite cheap, plus they're the only full system I can find.

All the big name exhausts, Blitz, Buddyclub, HKS, Milltek, all seem to be either catback or just come with a decat centre section, at least from all the scooby shops I know about.

Maybe I need to start looking at some broader shops to find their full systems.

If I could find a full system from one of the big names, I'd go with that.

[WhiteRAman]

Just give me a shout, I can do you a decat d-pipe and True 3" system (unfortunately with the "cannon" rear end that you do not like) for a very good price.
The up pipe is not totally necessary at this point in time, only when you get further down the modding road;)

020 8373 7336
Ralph