Logical Explanation
 

Hi,
This question is for 951 owners. Why was it
that Porsche decided on mounting the turbo
on the other side of the exhaust manifold? Besides creating alot of heat under the intake manifold, adding weight, all that
excess plumming would add some lag to the
turbo as well. Hope that some of you could shed some light on the reason behind the use of this set-up.

for the massive kick in the ass turbo lag ?
due to the exahust being on the opposite side of the intake. As far as I can tell the head of a 951 isn't that diffrent than the NA. They would have had to have a new head and a new everything to move it to the other side.

Matt

My guess goes along with LG's. A wee bit of lag is better than the cost of designing a considerably different head. There is not much space on the passenger side. These cars were expensive in those days. Redesign would have added considerably to an already expensive vehicle.

From what I have read they moved it because of the heat issue. By placing the turbocharger on the intake side away from the exhaust manifold (the hottest external part of the motor) turbocharger life was greatly extended. By moving the turbo and adding watercolling to it porsche was able to come up with a solution which greatly increased turbo life.

The downside of this is the turbo lag issue that you mentioned. But hey, at least we don't have to replace the turbos all the time like the 930 owners have to.

I agree with with the previous post it was moved to keep it away from the heat. Which also enabled it to produce more HP due to the denser air.

Quoting from Michael Cotton's Porsche 924/944 book [pages 72-73]:

"By installing the turbocharger on the left side of the engine, that is on the opposite side to the exhaust, the gas entry temperature was reduced by about 90 degrees C, and the flow of normal coolant water around the turbine housing kept temperatures down to 170 degrees C, even at full load."

-MAS