Paulyy

Very nice Bas!

Chris White

Have you thought about expansion in the headers and crossover? You built the system at ambient temps and you really want it to work best at high temps - the length of the pipes from head to turbo may increase as much as 1/4" at operating temps, that will add a lot of stress to the system. Slip joints or Inconel bellows can be added to the cross over pipe to relive some of the stress.
Some of the early SFR headers had cracking issues due to expansion.

BYW - on of the reasons that the stock system can be a pain to fit is that it was sized to fit a seal best at operating temps. I am sure that many folks have heard cars that leak exhaust when first started but then quite down when warmed up - the headers/crossover need to heat up and expand to seal correctly.

Chris White

Oh yeah - I should have added that the quality of the work looks pretty nice!! great project!

Chris White

Oh yeah - one more thing - be careful on the EGT bung placement, its a very tight fit when the engine is in the car, the heater return pipe gets in the way easily - but that can be relocated upward to get it out of the way.

reno808

great stuff

Dutch944

Thanks guys! PA, i think you mean f*cking awesome..


@Chris, yeah we have thought about the expansion. The entire header was contructed without tension and after the final welds we have baked it so now we are sure all the tension is really gone. At this moment it should only expand down and there is plenty of room.
Only thing we are thinking about is the turbo and how to mount it. Maybe we'll get a rubber mount to make sure it doesn't break the crossover pipe!

The EGT bungs; i'll fit the heater pipe first and than I'll check where i can fit the EGT bungs with the sensor but i'm sure we can manage that!

And again; thanks for the tips!

Chris White

The heating of the header can relive the stress caused by the welds - but it won't do anything for the expansion from the heat of the exhaust gasses.
The numbers say that based on a length of 20" (approx. total horizontal pipe length) of stainless steel (coefficient of expansion 17.3 x 10^-6) will expand .256" if the temp change is 800c.

That creates a lot of stress! Add to that the fact that the expansion takes place every time you run the engine up to temp and then contracts as it cools - that's a lot of cycling that will add to the fatigue of the metal and welds.

Rubber turbo mount....hmmmm.....I never thought of that. That would solve everything! I'll go out to the shop and weld some rubber together and see how it works!

Dutch944

Hahaha, not a real mount but more a set of steel plates on the engine with a sheet of rubber (oke not rubber but a softer material) in between.

The welds can definately hold the stress as the SS is 3.2mm thick with the weldpoint grinded to 45degrees to get maximum flesh; a weld of 6mm at the top and 3.2mm deep! That is mainly the reason that i'm not really afraid of cracks.

The length is about 58-60cm so that's 23". But we'll see what happens! When we're looking at the SFR headers they are not very different!

Chris White

All the SFR headers/pipes have either a single or double slip joint in the crossover pipe. Tim learned about that the hard way! A wise man is always afraid of cracks on anything that gets a lot of thermal expansion!

BTW - the only reason the turbo mount is critical is because of the oil drain. If you make your own mount then make a direct connection to the turbo oil drain with an AN fitting and hose so that movement of the turbo will not create a leak. If you do that then the physical turbo mount can be made to allow some movement.

Dutch944

Hmm oke! Learned something today :-) i'll discuss with my friend on how to make sure we don't get any cracks!

My turbo will not be mounted on the enginemount, and yes the oil drain will have a flexible hose connected!

URG8RB8

This is why I brought up the cracking comment on FB. Chris covered it very thoroughly above. I would highly consider incorporating a bellows. As you know, making any changes once back in the car is a total nightmare. Cheap insurance in my opinion.

Dutch944

Aha! So you're Eric!

But i suppose you mean to get a bellow in the crossoverpipe than? I have plenty of room and it's no issue at all to place one. Or do you mean to get one in the header? Because that will be a problem..

Else i'll just get a slipjoint, that will do the trick as well but thanks for the tips!

URG8RB8

Yes, that would be me. Many aftermarket headers replace the factory bellows with a slip joint. I have not seen any which keep a bellows in the factory location. I would incorporate the bellows into the crossover since that is where the problem with expansion will be the worst. I have not seen this tried before though. Again, best to discuss with fabricators, or Chris for that matter. The pics below sure are beautiful, anybody know who is the owner of this car?

Chris White

Finally got a chance to shoot a pic of the cross over with the bellows and the rest of the exhaust.
I am waiting for a new Tial flange to complete the wastegate exhaust pipe. The Wastegate is one of Tial's watercooled versions - more compact and easier to fit (the 968 bell housing does not leave room for the 951 style vertical mounting).

333pg333

Watercooled wastegate?