Rob Day

iTrader: (78)

My car 2001 UK300 running a few mods, somewhere near 330bhp/unsure of torque.

I have recently bought a new stainless manifold (not eBay shat) but I havent fitted it yet as I was curious to whether it is worth while or not?

Can anyone give me idea what im due to gain if anything?

Its running with a VF30, STI Pinks, 3" decat, STI UPpipe, Green Cotton, Walbro etc etc.

Thanks in advance
Rob

djandyg

iTrader: (2)

should give a nice gain, although im not sure what the normal manifold is like on a scoob.... gave a nice gain on my current car when i fitted a 4-2-1

have a read of this, it will explain the theory behind it...

HowStuffWorks "How do exhaust headers work to improve engine performance?"

Midlife......

iTrader: (2)

Hopefully Harvey might pop up

He has done a lot of work on headers / manifolds and how they affect performance.

From memory an OEM Ported and wraped set up would be a reasonable set up

Shaun

Rob Day

iTrader: (78)

Thanks for the above guys. Harvey supplied my Pinks and I have been in contact with him in the past regarding some headers but nobody has told me any ideas of possible gains. I know this kind of like "bhp pub talk", but surely someone will have an rough idea or simular experience they can share?

From a brief search on the web it looks like bhp gains are not going to be great but torque is considerable........................

The below look very simular to the actual ones although mine are two bolt up.
http://prosportgauges.com/images/pro...aruImpreza.jpg

rifleman

when i did full hks system,up-pipe and headers gained 39 bhp!!!
the headers made the car feel smoother and the turbo spooled up a lot quicker and felt quicker off the mark.

alcazar

iTrader: (2)

From what I understand from Harvey, it's in spool up you gain most.

Rob Day

iTrader: (78)

Thanks for that mate.

Im running apx 80bhp over the factory PPP power, but what i can gain from the headers who knows....

As for a smoother and quick spool thats sounds good. What car, mods and power are you running atm? and at what RPM do you seen the spool up?

Rob

Rob Day

iTrader: (78)

So is it worth doing it for a sub 350bhp car, or is it a case of driver preference, ie driving on & off boost they are worth of using, where as if you gunning it in every gear they are not going to do a great deal?

rifleman

mines a 97 uk car so 208 standard,running full hks system,headers and pipe,induction kit,walbro pump and newage wrx intercooler.getting 260.1bhp so good level for simple mods.turbo spools up from 2.5k now and just pulls nice and smoothly.

MK2VTR8VALVE

Yeah its def worth doing to a sub 350bhp car.
I think I can help ya here mate, I had my Type R mapped by Andy F last year & it made 325bhp & 301Lb/Ft.
I then got a set Harvey's ported headers & up pipe fairly recently. Got them fitted & JGM tweeked the map to suit. Result? 333bhp & 335Lb/Ft.
So that's a gain of 8bhp but more importantly 34Lb/Ft of torque.
It's def noticeable on the road- I find the turbo spooling better & the mid range punch is a decent improvement. Map tweek to get the best out of it though.

Rob Day

iTrader: (78)

rifleman - Wow 2500rpm spool, thats early. Im looking at 3500 at the mo . I only work 3 miles away from home so im constantly off boost to work and return home, so its mainly only the odd weekend when i get to see the VF30 making an impression.

MK2VTR8VALVE -Thanks for the info. Thats fairly amazing really. I mean as rilfeman was pointing out, simple mods too, nothing expensive or drastic to replace. My mapping was done by Andrew Carr recently during the Snow in December which was fun not. Anyway he's penciled me in for a Tweak as soon as im ready in the next coming few weeks.

Is there anything else thats noticeable, such as noise, idling, mpg etc.

I know I sound a little dumb with the questions and having read the above im definatly going ahead, but Im just now intrigued.

Rob

dunx

iTrader: (3)

Mine has always spooled a bit late, but all hell breaks loose at 3.5K and full boost is a mere gulp ! later....

Headers tend to help mid-range torque and top end power, IMHO, so best suited to higher power outputs. Not to say they won't work at sensible power levels....

Shame you didn't ask for a "demo" at the RS RR day....

dunx

P.S. It will reduce your burble too !

StevoT2000

Even unequal length headers?

Rob Day

iTrader: (78)

Thanks Dunx, I may take you up on that offer,,,, heard a little about your motor. What is it running atm? (close to 400/350 was the rumor).

The headers are UEL, and if that means i loose some burble then so be it, but as Stevo says, they are UEL not EL so I would not think this will change??? Last time we spoke I was looking for some EL so thats probably why you assumed i had bought EL.

Im going to get them fit this week, do you think that car will be driveable without a map tweak until Andrew Carr can fit me in very soon I hope???

Thanks guys
Rob

alcazar

iTrader: (2)

Dunx's car is a hoot to drive, once I got used to the 6-speed box, that is.

I asked Harvey about losing the burble and he told me it would burble MORE!

harvey

iTrader: (48)

Your best choice of headers will depend on the turbo you run and your spec.
My ported headers will give a noticable improvement in spool and response with noticably more torque across the rev range. The car will feel crisper/sharper with earlier boost and more willingness. The same boost can be produced at less duty cycle hence less heat or stress on the turbo. Customers have commented on a change in the exhaust note in that it is deeper.
As each car responds differently and most rolling roads give differing figures, I will not quote that my headers will give x power. However, I have never sold my ported headers to anyone that has fitted them that has not commented on the gains they felt and I have done many ported header sets.
Three bolt tubular headers of the type above (which I also sell) will be a disater on a 350 bhp car, the example quoted. They will produce the same top end power but spool will be typically 250 to 350 rpm further up the rev band. The car will feel lethargic until higher rpm. This results in travelling in one gear lower when you want immediate response. The tubular headers are more equal length so depending on the actual headers the off beat burble is less to the point that some header sets sound more like a Jap motorbike.

harvey

iTrader: (48)

Just come across this elsewhere :

AND

Aztec Performance Ltd

iTrader: (234)

The views from one the the most successful mappers around:

AndyForrestPerformance

My Impreza has aftermarket headers with 340bhp and I would consider fitting ported headers a backwards step on my car.

dunx

iTrader: (3)

Back to changes....
tubular headers are noisier at idle, cast iron does a good job of damping noise in comparison. There is a burble at idle, but it's less pronounced than with the std. set-up. At full chat the exhaust just roars like a superbike..... well at 7700 rpm it does !

LOL

dunx

P.S. Ta Jeff

harvey

iTrader: (48)

Andy Forrest actually did some tests on my ported headers, WITHOUT the matched uppipe. Somewhere I should be able to find the magazine article. The conclusion was that the ported headers without the matched uppipe got to within 5 bhp of the best tubular headers and better than some but that the spool and response on the ported was far superior.
With the matched uppipe the ported headers are a very good option in many cases and certainly in almost all cases where a standard turbo is in use and back to back testing and the experience of many people on here independently verifies that.
Because ported headers and matched uppipe cannot handle all modification specs I have a range of uppipes and also sell tubular headers for the right application. Making the right choice is very significant in terms of overall performance.