Equal length turbo header

With Turbo and Super charging you can create massive horsepower with vw motors.

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sidemarkers
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Equal length turbo header

Post by sidemarkers » Sun Dec 17, 2017 3:32 pm

There are interesting designs for the boxer subaru turbos. Has this been designed for an air cooled vw yet?
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buguy
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Re: Equal length turbo header

Post by buguy » Sun Dec 17, 2017 7:11 pm

I wonder how important it is? But it seems like the header everyone uses for draw through appears to be pretty much equal length. The over the alternator one you always see.

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petew
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Re: Equal length turbo header

Post by petew » Mon Dec 18, 2017 6:19 pm

I had a long discussion with my local Turbo guru about this. He really doesn't see what all the fuss is about. I mean, check the factory systems or most of the 'log' manifolds used on inline motors and large V motors. Sure, if you want to run 80psi on a shortfuse drag motor you might. However for most of mere mortals it's a bit ridiculous...

I mean check this...

Image

Explain to me how we'd feel the difference between that and this on the way to Crispy Creme?

Image

If I had an inline motor, I'd weld up a log manifold in a heartbeat. Better retention of heat, more durable, cheaper, more compact, quicker spool. The "Angry octopus" seems very appealing until you own one and have to fit it under your bonnet/decklid/apron.

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sidemarkers
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Re: Equal length turbo header

Post by sidemarkers » Mon Dec 18, 2017 7:34 pm

Good questions, reminds me of the carburetor and efi comparisons a decade or so ago.

The top manifold seems a bit overkill but not to someone looking to achieve 400 horsepower per liter of displacement.

Bottom pic of the log manifold isn't too bad considering that the runner lengths are a few inches from being equal, not a few feet on a VW depending on the specific header designs.

My #4 header runner is by far the shortest and the only cylinder that I cracked a jug, pulled studs on and the first one to ping.

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petew
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Re: Equal length turbo header

Post by petew » Mon Dec 18, 2017 7:37 pm

What's your manifold look like? Got a pic?

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buguy
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Re: Equal length turbo header

Post by buguy » Mon Dec 18, 2017 7:43 pm

My 1-2 header tubes are by far shorter than my 3-4.
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sidemarkers
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Re: Equal length turbo header

Post by sidemarkers » Mon Dec 18, 2017 11:55 pm

buguy wrote:
Mon Dec 18, 2017 7:43 pm
My 1-2 header tubes are by far shorter than my 3-4.
Image
Judging from the pic it looks as though #4 is your shortest too.

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Re: Equal length turbo header

Post by petew » Tue Dec 19, 2017 6:35 am

sidemarkers wrote:
Mon Dec 18, 2017 7:34 pm
My #4 header runner is by far the shortest and the only cylinder that I cracked a jug, pulled studs on and the first one to ping.
I'm far from an expert, but I feel like the symptoms you're describing are more about mixture than exhaust primaries. Were you running EFI or Carby?

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buguy
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Re: Equal length turbo header

Post by buguy » Tue Dec 19, 2017 6:47 am

My #4 is shortest for sure.

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sidemarkers
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Re: Equal length turbo header

Post by sidemarkers » Tue Dec 19, 2017 12:00 pm

petew wrote:
Tue Dec 19, 2017 6:35 am
sidemarkers wrote:
Mon Dec 18, 2017 7:34 pm
My #4 header runner is by far the shortest and the only cylinder that I cracked a jug, pulled studs on and the first one to ping.
I'm far from an expert, but I feel like the symptoms you're describing are more about mixture than exhaust primaries. Were you running EFI or Carby?
Been turbo/efi since 2001. Daily driver squareback that's been dependable minus a few mishaps here and there. When there has been a cylinder issue it's been #4.

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Re: Equal length turbo header

Post by petew » Tue Dec 19, 2017 5:25 pm

Have you been able to measure;
1. The heat of that particular primary relative to the others?
2. The heat of that cyl relative to others?
3. The mixture in that cyl relative to the others?

I guess, beside the issues of too much back-pressure/poor exhaust scavenging or a leaking exhaust valve, I'm struggling to see why you're having that ongoing problem.

BTW, came across this vid. Some interesting viewing re equal length runners.

https://www.youtube.com/watch?v=aSIpjNU1p4c

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Re: Equal length turbo header

Post by Buggsy » Tue Dec 19, 2017 6:30 pm

Swap your injectors around and see if the problems follow.

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Re: Equal length turbo header

Post by petew » Tue Dec 19, 2017 9:19 pm

BTW, What cooling fan system you using in your type 3?

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sidemarkers
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Re: Equal length turbo header

Post by sidemarkers » Tue Dec 19, 2017 10:50 pm

Buggsy wrote:
Tue Dec 19, 2017 6:30 pm
Swap your injectors around and see if the problems follow.
I tried this in 2005. Revamped the entire intake system and replaced the heads last summer. I might run a slightly cooler plug in the #4 cylinder in attempt to make up for the higher back pressure in the exhaust. For the most part the car is a comfortable compromise. No emissions, room for driving around with my 3 kids getting groceries, daily makes boost in the high teens.

Making an equal length header would help equalize the exhaust back pressure and allow the cylinders to have a more equal ping resistance. Maybe dual shorty headers with dual t2 turbos.

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sidemarkers
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Re: Equal length turbo header

Post by sidemarkers » Tue Dec 19, 2017 10:55 pm

petew wrote:
Tue Dec 19, 2017 9:19 pm
BTW, What cooling fan system you using in your type 3?
Standard doghouse type 1 shroud. This is in conjunction with a fan cooled intercooler, water/meth injection, and an rx7 oil cooler. The head temps are usually in the mid to high 200s and the intake air temp is usually about 20 degrees above ambient. There is hella room in the engine compartment.

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