blomman

My mechanic Perry Andersson who has worked on porsches since he was a kid and worked for a swedish rally pro named Bjorn Waldegard tells me I shouldnīt go for the SSI because it will run to hot and itīs much better for an air cold engine to go for the original heat exschangers pre -74 in steel. I know most of you guys from the states likes the SSI but is it anyone out there who knows if this is true? I have asked another really good porsche mechanic in Sweden and he tells me the same.

Jonas
Stockholm
Sweden
911sc 1978 Lindgrun

Steve Weiner-Rennsport Systems

Jonas,

SSI's are merely stainless-steel replicas of the factory heat exchangers used from '68 to '74.

There is zero operating temperature difference between the two: its simply a safety/longevity issue as the SSI's prevent carbon monoxide from reaching the cabin due to rusted factory HE's.

blomman

I know they are replicas of the original, and what my mechanic said was that the engine will run hotter with heat exchangers made of stainless, and he recommended me to buy steel instead.
Are you sure itīs zero temperature difference between the two?
jonas

J. Brinkley

UM,,,, ya he's pretty sure. lol
he wouldn't BS you

Amber Gramps

jonas, If Steve says it, it is gospel. Guys send him 911's, 930's, and the like, from around the country to race prep and tune. Call him at 11:00 PM and you can hear the cars on the dyno in the back ground, it's an unreal opperation. Your mechanic may be refering to "bypassing" or "back dating" or "heat delete" where oil could build up on hot headers and cause a fire. If you buy a good quality product and use them properly, you will be fine.

Peter Zimmermann

News to me (the heat issue). I've been using/installing SSIs for so long I can't remember when it all started; never a problem of any kind. Regarding SSIs being a "replica," I personally think that they're better than o.e. - maybe, just maybe, the only aftermarket part made that you'll hear me say that about!

blomman

Thanks,
Sounds like I should go for the SSI Iīve ordered.

jonas

blomman

Do you have to adjust the mixture after installing SSIīs?

jonas

Steve Weiner-Rennsport Systems

Yessir, sounds like you should,...

Adjust the CO to 2.25-2.5% and it will run better.

Edward

Hi jonas,

Steve W. and Pete Z. know their stuff; they speak from much experience. No disparagement to your wrench, but these two guys are the real deal. I do (and have) trusted them implicitely on all matters related to Porsche and things always turned out for the better. Which makes me wonder..... Do they offer advice on raising teenagers??...

Edward

Peter Zimmermann

First, buy a very large square of velcro. Apply said velcro to a wall, inside the house is best. Apply the other section of the velcro to the kids backside. As problems occur, stick kid to wall - don't forget to feed him/her once in a while. Sooner or later, they will be 25, their brains will form - hopefully - and...

JV911

Yoda and Obi-Wan

Steve Weiner-Rennsport Systems

I am a firm disciple of the "Peter Principle",....

lfornace

Jonas,

Your mechanics are not crazy. Stainless seel has about 1/3 the thermal conductivity of regular steel, so they (the SSI's) are not "merely" replicas, but will perform differently. While the differences might be negligible, the stainless will act more as an insulator, and heat will have a harder time (3 times harder) conducting from the heads to the heat exchangers, and thus engine temps (in theory) will be higher. However, the heat from the hot exhaust gases will also have a hard time conducting throught the walls and thus the exhaust gases will stay hotter, and thus the engine compartment air should be cooler. Furthemore, I would expect the heater to be slightly less effective with the stainless for the same reasons (more insulation = less effective heat exchanger).

Again, all of these changes will be slight (because most heat transfer will be radiative, not conductive), and likely go unoticed unless a very carefull test is performed. But you asked...

Lucas Fornace

LaughaC

Doesn't that mean it just takes 3 times longer for the stainless to warm up, and eventually it will reach the same temperature the steel units do?

Or... does airflow keep them cooler than steel because they are less heat conductive? Or do they take 3 times longer to cool?

Hmm...

'77 Targa
'87 Vette
'97 M3