Quote:
Originally Posted by afterburn 549
Dont know ....they must have had a reason..??
|
Yes they did.
Be aware that the addition of the restrictors came after the upgraded oil pump which puts out more volume at a given pressure. I suspect the flow to the heads remained about the same with the extra flow going to the piston squirters and bottom end.
Besides, what would Steve and Grady know that many of us do not?
Quote:
Originally Posted by Grady Clay
“ so are you suggesting not running cam line restrictors??”
Absolutely.
In my opinion this was a “fix” that Porsche did picking the lesser of two evils. The issue stems from the ability of an SC or Carrera being comfortable to drive at 2000 rpm and sometimes less. The piston squirters are necessary to keep the pistons cool. However they don’t open until 42-56 psi. With full flow to the cams, the main oil pressure at the squirters was too low. They didn’t open until the engine was above 5000 rpm when hot – too late.
Porsche’s “solution” was to limit (restrict) the oil flow to the cams, rockers and all the parts in the top end. Note this also includes valve guides. Of course the restrictor raises the pressure in the main galley that feeds the piston squirters. They then open at lower rpm. The problem, IMHO, is there was already marginal oil to the valve train when hot and low rpm. The restrictor exacerbated the problem 
I think Porsche chose to improve the piston cooling at the (evil) expense of valve train lubrication and cooling.
I’m not willing to build a nice engine with any preventable shortcoming. 
Best,
Grady  |
Quote:
Originally Posted by Steve@Rennsport
I'm in total, complete agreement with Grady on this issue.
Some of the hottest parts of the engine are in the heads and its totally counterintuitive to REDUCE oil volume & flow to these areas that need all the cooling and lubrication they can get.
Personally, I will not use the cam line restrictors and in fact, prefer to upgrade oil pumps where feasible. In addition to Grady's comments about power, improving oil scavenge in the sump by using either the 930 or GT-3R oil pump reduces oil temps and helps power output by keeping the oil level in the sump well below the spinning crankshaft.
|