Do SSIs without heat backdate cause higher engine temps?
 

I've got a '79 SC with a stock 3.0l and SSIs. The heat system has been completely removed, and I've got block off plates to either side of the engine fan. There are no hoses/ducts hooked up to the SSI heat exchangers. I believe the car runs a bit hot despite having a MOCAL cooler up front--I know, not as good as the Carrera cooler, but it should be better than the stock trombone, no? Further, the motor was removed less than 1k miles ago and fully degunked--no mice on the cylinder heads, the engine oil cooler is clean, etc...

My question, as in the subject, is does this cause/contribute to higher engine temps since there is no air circulating through the tinware around the exhaust manifolds? Put another way, if I traded SSIs for regular headers with no heat functionality would I see cooler temps? Yet another way, do all the half assed deletions and mods have unintended side effects in this case?

I've searched, and found only this thread. Unfortunately the conclusion is inferred by the OP, not shared, and it stopped there.

http://forums.pelicanparts.com/porsche-911-technical-forum/526069-does-ssi-overheat-engine.html


Thanks for any advice.

Tim

PS If consensus judgment or documented fact indicates the SSIs make the motor run hotter, anyone have a set of SS headers to trade, or do I go get another angle grinder???

There are many threads discussing this issue, most contained within the "backdate heat" threads.

It is in my (non-expert) opinion, without running air through the exchangers, you have two big heat sinks attached to your motor.

You MUST,...........MUST run air through the SSI HE's because its adding to the engine's heat load and they will eventually crack from excessive temperatures. If thats not a possibility, I'd recommend a set of headers since you're not getting any heat or defrost action anyway. Headers DO run cooler,.....

The engine can also run leaner which will increase its operating temperature.

I am no expert on the SSI but ;ike Steve said, I'd check for other causes of the engine running hot: lean fuel mix condition and/or retarded ignition timing.

Also, how hot does it run?

George

I saw a dramatic change in temps after removing block off plates and sending air through my SSIs.

which makes a lot of sense.
I agree, if you're not using heat, get headers, not HE's;