Kevin

I have promised to post the header mod for quite some time. The object here is to clean-up a few manufacturing nigglies, that will impede air flow to the turbine housing. I'm using the right side heat exchanger for the pictures. One thing that stands out, is that the exhaust ports to the heads are larger than the port (turbine inlet) going to the turbocharger! Porsche has always wanted to speed the velocity up in the collector as it goes into the turbine housing.. I will also say that, for the street 3.6ltr the factory short tube heat-exchangers/headers are hard to beat! Another words, put your money into aux oil coolers and a new suspension before spending your cash for a set of headers... You won't see any gains worth the $$$ spent.. I have yet to see a cracked set of factory heat exchangers....


The above picture is your standard right side heat exchanger, I want to thank Keith for the opportunity to buy this set from him... I hord these things so if any members have a set lying around, I'll buy them... As mentioned you can see the port differences... Pay attention to the oring sealing markings on the flanges.. The next picture shows what one of the major problems is on these units. As they were made at the factory, robots CNC welded these units together. There wasn't anytime put aside for deburring and collector cleanup. If you look at the picture you will see the primary header pipe from cylinder #1. The pipe needs to be unshrouded, this mean that you need to take a die grinder and cut away the stainless tubing to smooth the air flow upward to the flange.


Also, while you are there you need to smooth out the main seam that welds the collector together as it goes into the flange. In reality is varies to about 1" to 1.5" in length. All you are trying to do is to knock the weld down and smooth it out... I will post pictures as to what I mean..

This leads to another topic, when you install K24's the turbine inlet diameter of the turbocharger is too large, the flange opening diameter is smaller than the turbine opening. The correct way to fix this is to cut the flange off and weld another stainless flange and collar.. However, since we all know that I hate those laggy K24's.. there won't be a need to go over that DIY...

dr kenneth e garchow

now that would be a good reason to pull the system off and clean it also while doing the grinding

may i ask if anyone knows of any problems w/ceramic coating the exhaust system. i have seen a non turbo car w/it done and it looks great.

but wouldnt want to hold heat in the wrong place or cause other problems.

thanks

Kevin

Well Dr. Ken, if it was feasibly possible to cut the actual heat exchanger off and coat the headers then weld them up the gains would minimize lag and I'd recommend it. I suggest to all to ceramic coat the turbine housings on their turbochargers. Unlike Normally aspirated cars, we need the energy from the exhaust, and the heat maximizes the rotational velocity of the turbine wheel. On the 996TT, I coat the headers and port them to produce excellent lag reduction.

This DIY is for you owners to ring out the most on your TT's. I must caution all, that any material left inside the collector or primaries will damage the turbine wheel on start up.. This will cause a shaft inbalance and the turbo's will eat themselves up due to FOD... Foreign Object Damage..

dr kenneth e garchow

ok, i think i see the problem, cant get to the tubing because of the exchangers in terms of the coating?

what about the rest of the system, cats, muflers....?

911/Q45

This is great stuff! I'm going to guess that any post turbo ceramic coating is wasted.

Kevin

As far as coating the cats, there are 2 benifits, one is that when you have them coated, they will fire off sooner, this will help emissions but if you have replaced your cats, the next benifit is a reduction on radiant heat... This is a plus for all of your engine components and bodywork... There aren't any performance gains if you coat the mufflers, however again you willl be reducing the radiant heat... given off....

sfl993t4

Will the ceramic coating have any detrimental effect on the standard cat tubing? I've heard that mild steel headers can fatigue due to the heat trapped in by an outer ceramic coat. Interested as I'm considering doing this at the same time as the header mod and hybrid turbos.

Kevin

sfl993t4; Welcome to Rennlist

If you look at the headers, and look at your cats, they are made from stainless... The quality of the factory welds and the quality of German steel are Less likely to crack vs aftermarket... I have coated quite a few header in my lifetime and have not seen the tubing/steel split. Now wrapping the headers or cats with a thermal blanket will cause damage in areas of the county where it rains alot.. Like Seattle, or where there is road salts used to melt the snow/ice...

Kevin

Here is the port with 50% of the primary tube unshrouded. I took the time to grind and polish the perimeter flange where the factory fusion welds the collector to the flange. Be careful not to grind all of the weld. What you want to do is to smooth it out, and then polish it. There will be a smooth ridge when you are done. Don't get carried away and grind all of it, and open the diameter up, you will lose the bond between the flange and the collector.. The goal is to speed the exhaust velocity up into the turbine housing.

Jean

Kevin,

This is very informative , thank you for sharing.

If I see the pictures correctly, the O ring is gone from the flange, I am assuming there is no need for it. Do you need to do the same job on the flange attached to the turbo, to make sure both surfaces are properly mated?

Where these done using a Dremel and if so, could you please let us know what Dremel heads you use.

Thank you.
Jean

ca993twin

Jean,

How are things in Saudi right now? Sounds like you guys are getting hit pretty hard. I hope you and yours are out of harm's way.

I've never seen that part in person, but it looks like the header flange only has the marks from the turbo o-ring... the header flange is in fact flat. Kevin simply shined it up a bit. Kevin?

This sounds like a great mod when I install new turbos. I shoudl say... when viperbob installs my new turbos. I'm at 63,000 miles and (darn it) stock turbos are still fine.

Kevin

Jean;

The sealing oring sits in the grove that is cut into the turbine housing. Similar to the grovve that is cut into the cylinder heads. A dremel will work, but I use a high speed air powered die grinder with porting tools/bits. The flange then gets surfaced on a large stationary belt sander/surfacer..

Jean

Steve,
Thanks for asking..Yes it is pretty ugly, I am sending the family out in the next few days, they are targeting foreigners and workers in US companies mainly, so we are the ideal target.

Back to Porsches, you're right about the flange, I don't know what I was thinking. BTW, do everything that Kevin warns you not to, and you'll get those turbos fried..I bet you'll be happy to see them smoking the neighborhood!

Kevin, just saw your post. thanks.

Jean

Wet1

I'm in the process of collecting parts to piece together a twin turbo system...

If anyone has a set of factory or aftermarket twin turbo manifolds/headers for sale and or a TT oil scavage pump, please let me know.

Thank you!



BTW... Kevin, please keep up the wonderful tech tips!

boostid

Jean;

What are those beautiful wheels you have on your yellow 3.6T? Sizes?

Stay safe over there.

Thanks,
Hal
97TT Arena/Cashmere, RUF19s, SRDs, PSS9 w RS Sways