Custom Tuned Turbo Exhaust Systems

My exhaust system with the heat wrap removed. Surprising how well the material has held up after being wrap for over 3 years.
A good look at the T4 to T6 mounting flange adapter.

The primaries are stepped starting with 1.625" and increasing to 1.75".

A look down one of the runners.

Big HKS 60mm wastegate mounting pad.

Backside view of the Y-pipe junction. Those are an egt hookup and a quick disconnect hookup for a back pressure gauge.

A view into the Y-pipe junction.

Another overall view.

Beautiful Donnie
Thanks for posting

Paul

Thanks for the compliments.

The primaries are tuned equal length to within 1/4".
Some would think that long tube primaries would give a narrow powerband. On contrar. All of my engine specifications were configured together as a whole. Each component specification supporting another. With the resulting package, these pipes work very well from 4250 to 7800 rpm.

And they sound awesome!

Does anyone know what the chemical is called for cleaning stainless?

The Hendrix Group - cleaning stainless steels

simple cleaning with vineger or club soda but some good stuff on that site

Thank you, sir.

so what kinda back pressure to boost ratio do you get with those headers? with what housing/turbo?

also have you found a real tuning use for the one egt gauge? ive always been under the assumption that a W/B is used for actual a/f ratio and then you use egt's on each primary for individual cylinder correction( for removing lean/ rich cylinders)?

With the old turbo (T76) I had a BP/boost ratio of 1.5something:1. That was with a T4 turbine housing, Q trim, .96 a/r.
The new turbo is a FI91X. T6 split turbine housing, 1.15 a/r. I have not had the opportunity to get a BP/boost ratio yet. I'm going to be mounting an in-car camera to monitor gauges for me. I don't have everthing on the datalogger. I would imagine that with the extreme difference between the T4 and the T6 housing, I'm going to have much better than the past 1.5x number.

I read the plugs for individual cylinder temps. I'm sure it's not as accurate as an egt in each primary, and actually I've been thinking of trying such a system. When I first built the headers I had bought all the egt bungs to weld to the primaries, but have put off welding them in. The single egt at least lets me know if I'm in the ballpark. I primarily use the wide band sensor, plug readings, and timeslips to set the a/f and then check the egt as a secondary reading just to make sure I'm still in a safe egt zone. I don't use the egt as a primary reading.

Nice work, especially in the merge area of the crossover.

Have you ever found any data that supports the idea that stepped, equal length headers are a benefit in a turbo application? With the backpressure I have thought there would be no or very little benefit.

In the studying I did when I was first putting together my engine configuration, I spent a lot of time looking at the high end turbo motorsports classes. Especially F1. Studying the F1 turbo era, I found that tuned length headers were very popular. In fact, I noticed that the era started out with more log style manifolds and evolved into tuned length. Now, these people have R&D resources at their disposal that I can't even begin to imagine. I would not dare to second guess their decisions to use tuned length headers. If they found there was power in that decision, then I was on the band wagon too. Another well known tuner, Steve Kinsler of Kinsler Fuel Injection has documented that a turbocharged engine reacts to cam and manifold tuning much the same way a naturally aspirated engine does. His quote on cam selection for a turbocharged engine is, "Don't choke that engine". Again, who am I to second guess his successful experiences. A lot of times you don't need to go through the expense to do your own testing to find answers to some tuning questions. Just look at what other highly successful people have done. And people that have much more resources for testing than a simple hobbiest racer.

On the question of stepped primaries. Few people realize this, but the perfect primary tube for a 4 stroke engine is actually one that has a continual taper to it, right up to the collector. Of course, shaping a complete header system with tapered primaries is a huge undertaking and is very expensive. I have actually seen a tapered primary system. Pretty cool. Study 2 stroke exhaust systems and you will understand the importance of the tapered primary idea for a 4 stroke application.
Since tapered primaries is beyond the realm of most people to afford, let alone fabricate, the next best solution is to step the primary diameter at calculated intervals. My primaries should have had another step, but I really didn't want to end up with merging three 1 7/8" primaries. As I look back on it, I wish I had gone ahead and put that extra step in it.

The Y-pipe is something I'm very proud of. In fabricating it I found an angle that gave the merge a very interesting quality. If you take the Y-pipe by itself and take an air gun to blow air into one manifold side of the Y-pipe, the air blast will exit through the turbo flange opening. The interesting thing is, none of the air blast will exit the opposite manifold side opening. But rather, a suction would be present at that side. I was very pleased with that result.

CharlieF1. I'm glad you're getting something out of all this.

Curious on the type of stainless material used? 304 321,etc?

Also,how many miles did you put on your car with the exhaust wrapped?
Thanks
Looks nice! BTW.