"homemade" exhaust system, anyone try this idea ??

[mike mueller]

I was thinking (oh sh#$)that instead of dishing out the major amount of money for a real header system for the 914 I'd use this:
take the exhuast manifolds I have for the 1.8 motor, flip them 180* so that now the exhuast will flow torwards the rear of the car.Attach a pipe to each manifold and run them into a 911 style or even the factory muffler. Basicly this would eliminate the heat exchangers. Would I gain anything besides the removal of a good 20-30 pounds?

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Mike Mueller
Antioch, CA
1970 1.8

[JP Noonan]

Exhaust systems dwell in the relm of thermodynamics, velocity is more important than volume, as is turbulence, scavenging, tuned runnier length, etc.

The following is all IMHO

Pro: like you said dropping 15-30 pounds of the "Brazil" type of bass-ackwards heat exhangers. Most likely the engine will run much cooler. The motor may gain a lot in the upper RPM range with those larger diameter pipes.

Cons: Most likely you'll lose some low end torque compared to a stock system, and high end hp compared to a tuned after market exhaust. The sound may be less then desirable.

That said I put an homemade (well actually I worked at NAPA and took a peice of this pipe from a 72 mustang, and that piece there from a Caprice, etc.) exhaust and welded the peices together. Sounded great, except at 2600-2700 rpm there was a hell of a resonance freq which overpowered conversation. It gained .5-.6 tenths in the quarter mile. However, I did buy the long tube headers, I think this is where most of the gain came from.

Since you won't have much in the way of scavenging, maybe a crossover tube would help? Paint the exhaust with any spray paint, at the point it stops burning off add the crossover. Of coarse this is all subjective unless you lots-o-time and a dyno, in which case buying already made headers would by smart.

[mike mueller]

Opps, i forgot to mention the cross-over tube, yes I'd install one as well.
Thanks for the input.

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Mike Mueller
Antioch, CA
1970 1.8

[jmcleod]

i don't know if this applies to a 1.8L engine but the exhaust stud spacing and position on a 2.0L head is such that you cannot flip the heat exchanger by 180 degrees as the holes and studs will no longer line up. i may be mistaken but i think this is true for vanagon heads (yes, i know square ports) and 2.0L 914 heads. i toyed with the idea of putting a 2.0L in a vanagon,even bought bus heat exchangers, only to find this problem. fortunately the heat exchangers were not too expensive as i wasted that money.

[tmk]

On a 2.0L head you can flip the heat exchanger by 180 degrees. This was done to put my 2.1L on the Dyno at Jarry Woods Inc.

TMK
73 2.1L

[turbo2.0]

Hey Mike, I know an exhaust modification that may help...oh, not that again.
Anyway, seems to me that if I were to try and design an exhaust system for a naturally aspirated type 4 (without the help of a dyno)I would try to build a 4 into two into one, with small to moderate size primaries to maximize velocity and scavenging. Equal length of course, with generous but smooth collectors, and a very free flowing muffler. I would also have it ceramic coated, if I could afford it. Or, I would look around. I would be surprised if someone doesn't already make one of these. Then I would just try and copy it, or buy it. No sense in re-inventing the wheel, right? BTW, with an old set of exchangers, a header from a dune buggy, and a welder it's amazing what a guy could come up with.

[mike mueller]

Sam,
Headers are made for the car. I just don't feel like spending a minimum of $350. I was figuring by doing it this way I'd save some money and weight at the same time. I just don't see this way being any worse than the factory setup. I guess it's time to crawl under the car and test it out.

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Mike Mueller
Antioch, CA
1970 1.8

[turbo2.0]

Any chance you can get close enough to the high price headers to take a couple hundred measurements? I have a new wire feed MIG just waiting for me to screw something up.