Bardman

Looks good! Feedback?

O5C4R

will hopefully get to go for a drive tomorrow or Thursday, i'll let ya know, double demerits will probably start Friday, this nanny state country so pretty keen to give it a squirt before the fun police come out in force

Mechanic said the quality and fitment were excellent, O2 sensor a little tight

FLT6SPD

I did not read through the whole thread, but can some explain what 4th pipe from the collector is all about? Whats the purpose? Wastegate dump tube for the vornado?

Thanks

Buteo

Paraphrasing. So I'm sure someone can correct me if this isn't spot on.

Creates a bit more of a "vacuum" by emptying the exhaust completely. Essentially goes along with their "tuned header" description.

FLT6SPD

This creates scavenging? How does it evacuate if sealed at the end? I am intrigued.

Bardman

Time for the fluid dynamics gurus to step in.

Jamie@dundonmotorsports

We just decided to add another tube on there to add weight and baffle people..

Not so much fluid dynamics as it is pulsed gas flow. The gasses leaving a cylinder when an exhaust valve opens creates a pressure wave (imagine the picture of a bullet leaving a gun...) That pressure wave expands, reflects and is redirected back to the head. If the timing is correct you get the reflected expansion wave (now a "suction wave") back to the cylinder head when the exhaust and intake valve are both open. This allows more air to be removed from the cylinder and also pulls fresh air into the cylinder through the intake valve. Some headers get this right by accident, some of them get this right by design.

This is why we call all of our designs "tuned length", not long tube as longer isn't always better. It's the tuning that creates power throughout the entire powerband.

The 4th tube is a patent pending design that aids in a number of parameters that enhance our ability to tune the headers...

Can't say too much as not just customers watch this thread...

Bardman

I understood that tuned headers only work over a certain RPM range (due to the fixed length of the headers combined with variable engine speeds leading to the rebound timing only "working" in certain ranges). Is this what you mean by working over the entire "powerband" - ie a certain rev range. If so, what range have you targeted?

Bill Lehman

That's my understanding also. The blanked off tube comes off one of the 3 cylinders and that may broaden the rev range of the "tune". A similar theory applies to the intake side. When I was @ McLaren we went to two lengths on the intakes to broaden the range.

Rovman

Hey Mike, I will be there (if my schedule holds) with MVP for the 3 days. My only engine mods will be the headers/filters / and tune. Hopefully we are in the same run group. Than we can run tests the whole 3 days if we desire.......

okie981

I think where the fourth tube ties in to the collector it is sharing sonic/pressure pulses with all 3 cylinders, not just one, but that's based purely on what I can see from the few photos I've seen on this thread.

okie981

Dead sexy, baby! (Spoken in Fat Bastard voice, Austin Powers movie quote)

electron mike

Nice! There will be several other GT4s there as well, so I'm sure we can do some experimental drag racing for comparison.

John@Fabspeed

PA is so boring, wishing we were located in TX so I could get in on this haha

Bill Lehman

John, Maybe we can organize an East coast run at WGI.