986 Forum - The Community for Porsche Boxster & Cayman Owners - View Single Post

thstone · 05-22-2019, 06:40 AM

I'd call this a somewhat "tired engine". Nothing is hugely out of whack, but the compression should be somewhat higher (more like 160) and the leak down numbers somewhat lower (more like 5%). And yes. this could affect acceleration.

Most Spec Boxster's dyno in the low-to-mid 190's at the rear wheels. The stock exhaust might account for 5-7 hp. Do you have the under drive pulley installed? If not, then that might be another 3-4hp especially if you still have a/c. Do you still have the cat's? There is probably another 2-3 hp there.

If we use the upper range of those numbers: 7+4+3 = 14. 180+14 = 194. Which is about right. If we use the lower range, the you might be down a couple of hp compared to a stout SPB engine..

I also sent you this info via FB messenger.

Here are the compression and leak down numbers for my last engine just before it failed. It was clear that cyl's 4 and 5 were not happy. The engine still made decent power but the engine felt "off", like it wasn't its old self.

05-22-2019, 06:40 AM	#3
thstone Certified Boxster Addict Join Date: Nov 2010 Location: Los Angeles Posts: 7,669	I'd call this a somewhat "tired engine". Nothing is hugely out of whack, but the compression should be somewhat higher (more like 160) and the leak down numbers somewhat lower (more like 5%). And yes. this could affect acceleration. Most Spec Boxster's dyno in the low-to-mid 190's at the rear wheels. The stock exhaust might account for 5-7 hp. Do you have the under drive pulley installed? If not, then that might be another 3-4hp especially if you still have a/c. Do you still have the cat's? There is probably another 2-3 hp there. If we use the upper range of those numbers: 7+4+3 = 14. 180+14 = 194. Which is about right. If we use the lower range, the you might be down a couple of hp compared to a stout SPB engine.. I also sent you this info via FB messenger. Here are the compression and leak down numbers for my last engine just before it failed. It was clear that cyl's 4 and 5 were not happy. The engine still made decent power but the engine felt "off", like it wasn't its old self. __________________ 1999 996 C2 - sold - bought back - sold for more 1997 Spec Boxster BSR #254 1979 911 SC POC Licensed DE/TT Instructor Last edited by thstone; 05-22-2019 at 06:44 AM.