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Engine Specific Info and Questions => IDI Engine => Topic started by: rabbitman on December 16, 2006, 06:54:47 pm

Title: exhaust size
Post by: rabbitman on December 16, 2006, 06:54:47 pm

what is the most restrictive part of a 1.6 na exhaust system, toilet bowl style? Does any rabbit gas or diesel manifold bolt up? Is it more important to open up the intake or exhaust?

Title: exhaust size
Post by: rabbitman on December 16, 2006, 07:20:50 pm

My '79 rabbit 1.6 gas inj parts car has the old bolt on dual down pipe. Would I be wasting my time to put it on my diesel? It's 0 degrees F out now so I didn't look at it very close, it might be rusty like the rest of the car. I bought a '84 rabbit with ac and it has a 4 speed fan and '82 without ac has a 3 speed fan, anybody seen that?

Title: exhaust size
Post by: wolf_walker on December 16, 2006, 09:57:28 pm

I've been wondering the same thing.  
The pathetic stock downpipe looks the worst on the 1.6NA setup, but are there gains to be had for the expense of a dual downpipe manfold?

Title: exhaust size
Post by: veeman on December 18, 2006, 10:55:35 am

Quote

The pathetic stock downpipe looks the worst on the 1.6NA setup, but are there gains to be had for the expense of a dual downpipe manfold?

The gas rabbits and some of the early Mk2's had the same style manifold and it's commonly regarded as one of the worst stock manifolds VW put on their cars.  All four cylinders dump into the one outlet and as a result, the runners aren't equal length.  The clip/ toilet bowl is good for installation / removal and does account for some flex, but it's definitely not aimed at performance.   I replaced the one on my 83 GTI with an earlier dual downpipe system and I could immediately tell the difference, especially in the top end.  Perhaps a 5-7% gain in power?

I've never tried this on an NA diesel, but I'd assume that it would help that engine breath better as well.  I believe you can go slightly larger on the exhaust system from the downpipe back as well, but probably not much bigger than 2" if the engine is stock.   If you've got the parts, I'd say go for it... the only thing that's sometimes tough is getting at all the exhaust studs, especially if they're old / corroded.

Title: exhaust size
Post by: burn_your_money on December 18, 2006, 08:05:20 pm

I'd do it for sure if I have a NA. You'll need to change the exhaust where it meets up with the new downpipe though

Title: exhaust size
Post by: clbanman on December 22, 2006, 08:46:35 am

Weighing the initial cost and the life of the part, would the factory dual manifold be preferable to something like this for a 1.6 NA?
http://www.innerauto.com/browse/year/1985/1989/vw/golf/headers/?ref=S1161368748W453914ac6fba6&label=85+86+87+88+89+VW+Golf+Headers
For the guys running headers, what is a reasonable life to expect (considering life in Ontario with lots of salt in the winter)?
How common or easy to find are the dual downpipe manifolds?

Title: exhaust size
Post by: burn_your_money on December 22, 2006, 04:45:10 pm

I've had 5 different cars in the past 2 years with the dual outlet manifold, over 20 years old and still in great shape (except for the studs)
If you find a german rabbit it's pretty much a guarantee that it will have a dual outlet on it.
Make sure you get both braces for the dual outlet setup, otherwise they just crack. I have 2 sets of braces that I'll give away for the cost of shipping if anyone is interested. They aren't mint, and might need some minor welding, but they are much better then nothing.

Title: exhaust size
Post by: wolf_walker on December 22, 2006, 08:57:02 pm

Do the aftermarket downpipes from such as TT use the brackets?