Heat exchanger question

jvb914 · 01-09-2015, 03:34 AM

I am switching from a 1.7 to a 2.0 engine on my '73 914. My question is. Can I use the heat exchangers from the 1.7 on the 2.0 engine? Is it necessary to get 2.0 exchangers. Are they different? Also can I use 1.7 exhaust system?

Dave at Pelican Parts · Dave at Pelican Parts's Garage

You can use the 1.7 exhaust, it bolts right up. You can also use the 2.0 exhaust, but you have to use all of it--exchangers, muffler, muffler hanger, gaskets. You can't mix and match; use all of one or all of the other.

--DD

The cap'n · 01-09-2015, 11:48 AM

What Dave says is true, but you can expect some performance loss due to the smaller diameter of the pipes.

The Cap'n

jvb914 · 01-11-2015, 02:50 PM

Thanks Dave for the info. Cap'n as far as performance loss what are we talking about? How much? This car will just be a daily driver ,summer driving. TOOO cold in the winter. Would it be a noticeable difference in performance?

Dave at Pelican Parts · Dave at Pelican Parts's Garage

I doubt you'd notice a difference in any reasonable street driving. That said, I don't have first-hand experience.

--DD

malcolm2 · malcolm2's Garage

Quote:

Originally Posted by The cap'n

What Dave says is true, but you can expect some performance loss due to the smaller diameter of the pipes.

The Cap'n

That is the first time I heard that. So the 1.7 - 1.8 early exhaust has smaller pipes that the 2.0? You can easily see the differences in the late vs. early exhaust and even the shape of the pipes after the HE on the early 1.7/1.8 vs. 2.0, but never noticed the ID.

Something else to look for, I guess.

The cap'n · 01-14-2015, 04:38 PM

Quote:

Originally Posted by malcolm2

That is the first time I heard that. So the 1.7 - 1.8 early exhaust has smaller pipes that the 2.0? You can easily see the differences in the late vs. early exhaust and even the shape of the pipes after the HE on the early 1.7/1.8 vs. 2.0, but never noticed the ID.

Something else to look for, I guess.

Yes, the 2 liter exhaust pipes are quite a bit larger in area than the 1.7, most obvious by looking at the wall thickness in the OE versions. They're also shaped a bit differently and require a different muffler and muffler bracket.

malcolm2 · malcolm2's Garage

I have seen a few posts about the pipes failing. I bet the % of failures might be higher for the 2.0 version, since the wall thickness is smaller. Just a thought, but curious about what people actually experience.

The cap'n · 01-15-2015, 01:28 PM

In the 40+ years I've been working on 914s, the only pipe cracks I've ever seen on 194 HEs are in the late ('75-'76) manifolds. Never in the earlier versions. I live on the west coast, so weather isn't a factor, but the cars here likely get driven a LOT more, so it should even out.

The Cap'n

TheCabinetmaker · 01-15-2015, 03:39 PM

all the failure of cracked heater exchanger pipes I have seen have been on the stainless steel aftermarket types. Never seen a stock one crack. have not seen many of the smog control ones though. seen a lot of them stock ones rust out however!

If you upgrade to a side shifter tranny, and keep the 1.7 exhaust, you will need a custom muffler hanger bracket, easy to fabricate.

Dave at Pelican Parts · Dave at Pelican Parts's Garage

You don't need a custom muffler hanger--the same one was used on all 1.7s, including the side-shift 73 1.7s, and the 74 1.8 as well. Just use the 1.7 muffler hanger if you have 1.7 exchangers.

--DD

TheCabinetmaker · 01-18-2015, 04:39 PM

Quote:

Originally Posted by Dave at Pelican Parts

You don't need a custom muffler hanger--the same one was used on all 1.7s, including the side-shift 73 1.7s, and the 74 1.8 as well. Just use the 1.7 muffler hanger if you have 1.7 exchangers.

--DD

maybe it was when I put a 2.0 liter motor in an early car that still had rear shift tranny????? At any rate it might have been that car, neither type of muffler hanger fit with that combination, had to customize it. Tried BOTH types of stock hangers and neither worked. So I might have been a 2.0 liter exhaust system would not fit with the stock 2.o liter exhaust hangers on an early tranny???? memory is fuzzy

The cap'n · 01-18-2015, 04:42 PM

There are THREE different hangers, one for 1.7/1.8, one for 2.0 '73/'74, and one for all '75-'76 engines. The year of the transmission doesn't matter.

The Cap'n

TheCabinetmaker · 01-18-2015, 05:38 PM

One of the stock hangers wont fit with one of the tranny / exhaust combos, I know that from experience. The hanger I believe would hit the rear shift mechanism. don't have that car set up that way anymore, so I cant look to see what it was, but for sure a custom hanger had to be used with that combo, and I think it was a 2.0 liter motor, maybe with 1.7 exhaust, maybe 2.0 liter exhaust, on a rear shift tranny. I tried both the 1.7 and 2.0 liter hangers and neither would work The 2 liter and 1.7 hangers are different heights, as the mufflers on these two types have different heights for the hanger pick up points. (header to muffler flange bolts is hanger pick up point)

So I am pretty sure it was an late hanger on a early tranny that would not work. had to use the 2.0 hanger for correct height of muffler, but that hanger was made for a side shift tranny, and hit the tail shift mechanism. that hanger (2.0 liter) sits lower than the 1.7 liter hanger and I think that lower height was causing interference with the rear shift mechanism.