So after some searching....no classic thread but some old ones.

I have a set of 1.7 SS HE's that are to go on a 2.0.

Questions:

1. Is there anyone who has done this and was there any noticable performance issues ?

2. Can anyone confirm or know the tubing ID differences?

I.m aware of all the other differences. This is for a 73 configured exhaust.

When SSI was making the SS HEs they used the same tubing for both 1.7/1.8 HE and the 2.0 HE. The Stainless tubing they used was the same O.D. as the stock 73/74 2.0L HE used but the tubing is slightly thinner wall and so I.D. is slightly larger.

I don't know what Danske is using now that they bought out SSI.

You do have to use a 1.7/1.8 exhaust hanger and muffler to use the 1.7/1.8 SS HEs.



Jim

While the pipe diameter may be the same on the old & new SSI HEs for 1.7/1.8 & 2.0, the design/routing of the 1.7/1.8 is different & won't allow you to use a 2.0 OEM type "Banana" muffler & many others designed for the better breathing needed for the 2L motor.

OEM 1.7/1.8 HEs are enough smaller that they will "rob" 5-10% of the HP/TQ, & using a 1.7/1.8 muffler with bigger pipe SS 1.7/1.8 HEs will have a similar restriction effect.

IMHO, you'll be much better off selling the 1.7/1.8 SS HEs & get a proper 2L set for your 2L motor - if you bought yours new from a dealer, just contact them to do an exchange (may be a price difference), & if they're used - just sell them & get 2L ones. This is not just my recco, but also what my factory trained on 914s back in 1969 Porsche Tech who's had his own shop since 1972 & specialized in 914s there (in case the jag-offs chime in ).

There were some FS in our classifieds here, at 914club.com & evil-bay & TheSamba.com all the time used for not too much (compared to a new set).

Here are diagrams & pix below on the differences, which you can find at the page linked below, but also take some time to cruise around Jeff's 914 site too.

http://bowlsby.net/914/Classic/TechNotebook.htm

> p914.com (& .net & .org) is another great resource, as well as 914 Info page on here.






.

Good Luck!
Tom
///////

Very good informational post

Ok.

I know the configuration differences and thanks for the post Tom and others.

So I can surmise this between just the heat exchanger component....no withstanding any other exhaust or heating component:

1. SSI heat exchangers between all displacements have the same internal tube ID's but only the 2.0 has a different tube confifuration.

2. OEM stock HE'S TO SSI have the same tube OD but the SSI exchangers have a larger ID due to the thinner wall thickness on thebSSI exchangers.

Any quesses or experience with performance characteristics?

I think the point is that you're going to have a hard time finding a 1.7 muffler that will flow enough to give you the same performance as a 2.0 muffler, even with the SSI heat exchangers. So, you might take a slight performance hit. How much? No idea. I'm not sure anyone here knows, since it doesn't sound like anyone has tried that particular combination.

I tried to state all othwr components being equal.

I already know there may be an availabilty issue with mufflers. That is due to the upward bend in the aft section of tubing.

I know I can get a set of 2.0 SSI for a price. But my 1.7 set is in almost perfect condition. So I was wondering if anyone else has done it.

So assuming any affect the upward bend has on performance?

I doubt is anything to worry about until you start talking big hp. Have Chris Foley at tangerine make you up a nice ss exhaust for your he's.

The upward bend has zero impact on performance.

Having Tangerine making you something? Sounds like a dream budget for him.

I have a set of 1.7/1.8 SSI HEs with a Triad muffler that came with the last 914 I bought. I don't have the car together yet and have not tested the combination. The PO was impressed with the way it ran but I have no info. It maybe quite some time before I test the combo because the motor going into the car has a tri-Y header similar to Chris'.

My old 1971 1.7, I switched to 2.0 SSI HEs and a Bursh muffler and it made a noticeable difference.

Jim

Sort of. This will be tied to a "budjet" build that McMark is doing So in keeping with that idea I want to use good existing components without impacting expected performance.

Right now I want to ditch the Bursch. A Triad was what first came to mind.

How big are you going?

Your stock 2.0 Djet you sold me and stock parts Kevin. Bowlsby is hopefully got the MPS as we post.

The jugs are actually Jim Hoylands old Mahle pistons redone.

I don.t think there is any appreciable difference and any coin I save on new HE I figure I can put towards a nice muff.

So what are we talking here. Less than 5 bp? I highly doubt you will ever notice a seat of the pants difference. And I am confident driving skills in the twisters will overcome that minor reduction. I've used 1.7 HE on a 2.0 with euro pistons and a lightened flywheel. Stock injection. Very satisfying. BTW: Have Jeff test your harness too. You won't regret it.

Thanks Rick...didn.t think so either.

Have a new harness from him so all should be good there.

If McMark is building your engine, ask him for muffler suggestion He knows a thing or two.

He does indeed. This won't be a "performance" build.

Just a stock 1.7 to 2.0 with good parts. McMark is just putting together the long block with good used re-built parts.

Decision made. Triad it is utilizing the 1.7 HE's that I have already.

I start a new thread when I have all the parts.

I was in a similar situation Having a set of the 1.7 configured SS HE's and putting them on my 2056. Not a "performance build" but HAM heads and mild Raby cam 9590. Dave of Triad built me a muffler that looks good fits perfectly AND sounds great. Not too loud, just right.

Sorry I can't speak much for the performance since I only have about 3 miles on the engine, but I like the sound.

You won't be disappointed.