*Sonic*

Some header pics, after doing some work on the car today

They look a state


New ones that have gone on


Hmm, you can see how restrictive they are !!




Look at the difference on the ported ones, with the old gaskets





Finallly some block shots





Not ran the car yet, but will take her out for a run tomorrow to make sure everything is ok now the new headers are on

If all is ok, I may be at well lane tomorrow (but not running)

Steve

*Sonic*

Forgot to mention, big thanks for Jim Litten for supplying the new headers

911

Did exactly the same job on Friday!
Took about an hour using the right tools, very easy.
I'm told the turbo will spool up much quicker, and come on boost about 500 rpm sooner.
The amount of cast iron that came out was huge.

Tell us what effect it has had! My engine won't be back for ages yet.

911

Bob Rawle

When doing this you shold only potrt the side of each joint breceiving gas flow not the side exiting otherwise you get an expansion bulge which slows gas flow. Apart from that its a good mod but I wouldn't say it brings boost in earlier as you have deristricted the gas flow it has slowed down somewhat. Did you port the up pipe as well ... thats even more important, do both ends as there is a rough exit. Also the cross pipe is sleeved and requires "rolling" back the inner in addition to porting.

bob

bob

PeteTheFinn

It looks like the id of the heads and headers is about the same. Just the gaskets seem bigger. Will porting actually make it flow more? Or do the gains come from reducing reverse flow? Is the id of the uppipe as big as the ported outlet of the headers? Surely creating a lip there won't aid flow?

*Sonic*

Only the up-pipe to headers end is ported, the turbo end was tried but the weld is so close, and doesnt port very well

So I may have to invest in a new up-pipe (non OE)

minor_threat

Very cool! What's the material wrapped round them Sonic? (I gather it's to reduce noise?!)

I'm always bewildered by how restrictive the standard parts are and how much difference smooth airflow makes!

*Sonic*

Not sure what the material is, I 'think' its DEI Heat Wrap, but I would need to ask Jim Litten as to what he used, the wrap is basically cos the heat shields are cr@p

Just got back from well lane and got 255bhp 242lb/ft torque

Not too shabby for a UK with PPP, and a broken up-pipe

S

911

Thanks for the up pipe bit Bob, i was going to leave that as the manifold to heads will make the biggest difference. Using a quick measure, the ingoing end of the U/P is the same dia as the outlet of the manifold on my Sti v3.
Guess I will now have to dismantle the cross pipe to check they are ok.
Porting the obstruction to gas fow only is a key tip too!
911

NM

What did you have before ?

Cheers

Neal

*Sonic*

the only other time it was on the rollers, was when I first got the car, and I had just a decat centre & less restrictive backbox, and an AE800 ECU

and I got 239 bhp 219lb/ft

My car was running a tad rich yesterday, but its still a decent improvement

minor_threat

Not too shabby at all! That gives me hope for my UK classic!

Pavlo

They are not terribly restrictive, as the ports in the heads are about the same size as the entry to the headers. All this "grind it out to the gasket line" is utter bollax, the exhaust ports are large enough as they are, you just need to make sure you don't have a lip as the gas flows into the headers, and that the headers are clean and tidy as far in as possible.

The most restrictive bit is the exit from the RH header to the up-pipe, this is the bit that needs the most work, and with proper tools you can get right in to remove some lumps inside the header too.

Paul

911

Paul, is all this grinding activity close to Grouppe s header performance?
I'm only doing this work due to the engine being out of the car to have the heads done.
Doing the up-pipe this week.

There has been a thread recently that someone has had a positive result with Grouppe tube headders, and another nothing, both measured on (different) RR's.

With an Andy F TD05: Grouppe headers giving the same as flowed cast iron?

There is the weight saving also!

911

Aztec Performance Ltd

iTrader: (234)

"Also the cross pipe is sleeved and requires "rolling" back the inner in addition to porting."

I have ported headers (thanks Paul), but does the cross pipe need any modifcation? What this 'rolling' that BR mentions?

Bob

harvey

iTrader: (48)

Ported O/E headers and up-pipe, if done properly, will show good gains. There is no point putting on Gruppe 'S' headers AND up-pipe on say a TD04 as the system does not flow enough air. Some cars have aftermarket up-pipes that are too large a diameter which slows down the gas velocity to the compressor turbine resulting in very poor spool. Gruppe 'S' come into their own at higher power levels, maybe in the order of 325 bhp up over and show good gains over ported cast.

There would be further small gains from doing the cross over pipe if not already donebut when I say doing the job properly I mean up-pipe and down pipe and ALL joints including cleaning out any roughness you can reach. Takes me a lot more than an hour maybe three hours.
Remember: In direction of gas flow, conical in parallel out and all rag and cast marks removed.
Have a set coming off a car next week-end if anybody is interested.

PeteTheFinn

Should there be a lip to reduce reverse flow? Or is it better to just match the inlet and outlet?

jim litten

Just to add, that all flanges that I grind out are tapered and not just ground out for grinding 'sake and yes I do grind in the direction of flow, as my whole day job relates to flows of gas, steam, and liquids so I do know something regarding flow. The reason I grind out the outlet to the uppipe (and I inform people of this) is that I suggest, and most people use, aftermarket uppipes, and having a step into a larger bore uppipe will cause turbulence in the gas flow.

As for whoever asked what they're wrapped in, is it exhaust wrap for retaining heat in the headers, not for noise reduction.

*Sonic*

Thanks Jim

Old headers are in the boot ready, and tbh its only that bit of heat sheild that is covered in surface rust