Compression for a stock 1.7

zwh · Post by **zwh** » Tue Sep 25, 2007 2:23 pm

What are good compression numbers for a stock 1.7? I'm getting around 125 psi for all 4.

Dave_Darling · Post by **Dave_Darling** » Tue Sep 25, 2007 7:48 pm

Warm, battery in good shape, starting system all fine, throttle WOT, all plugs out? That's probably a little on the low side. Figure 140+ when fresh, 100-110 PSI would be the wear limit.

Unless you're in Denver or elsewhere at altitude, then 125 is probably just fine!

--DD

zwh · Post by **zwh** » Tue Sep 25, 2007 7:55 pm

Dave_Darling wrote:Warm, battery in good shape, starting system all fine, throttle WOT, all plugs out? That's probably a little on the low side. Figure 140+ when fresh, 100-110 PSI would be the wear limit.

Unless you're in Denver or elsewhere at altitude, then 125 is probably just fine!

--DD

Thanks.
Altitude is around sea level.

Since 125 is a little low, would this indicate a tired engine? Or could it still remain running healthy for quite a long time?

raygreenwood · Post by **raygreenwood** » Wed Sep 26, 2007 11:40 am

Also I tend to find that I do not get the 140 ish comprssion until the engine is well broken in. Usually for sure by 5k miles. I see 130+ by 1500-3k miles. Ray

Dave_Darling · Post by **Dave_Darling** » Fri Sep 28, 2007 12:56 pm

zwh wrote:Since 125 is a little low, would this indicate a tired engine? Or could it still remain running healthy for quite a long time?

Both, I would think. A little tired, but good for a while yet. I wouldn't worry about it until it got down to the 110 range.

You do realize that these are all rules-of-thumb and not hard and fast rules, though, right?

--DD

raygreenwood · Post by **raygreenwood** » Mon Oct 01, 2007 4:58 pm

Forgot to note....if by chance the pistons have been changed to the dished variety..which are not the correct ones for a 914....125 would be about right.
Have Dave....keep your fingers crossed. If my interview went well on Friday......we might be neighbors. I was in Palo Alto for an interview for a company whose plant is in San Jose. Ray

Dave_Darling · Post by **Dave_Darling** » Tue Oct 02, 2007 7:40 am

Get ready for a rude shock about property values, Ray! Rents are absurd, purchase prices are completely obscene!

--DD

Post by **Piledriver** » Tue Oct 02, 2007 6:15 pm

Also note if it has sat for any length of time and there is any rust on the cylinder bore, the readings tend to run low until you run it for a few K.

raygreenwood · Post by **raygreenwood** » Wed Oct 03, 2007 8:46 am

Dave.....yeah I have been looking around already. Purchase is out of the question. The rents....are about 30-40% more than Dallas...apartment wise....since I will be too busy to maintain a house at all. If the job ccomes through....and the $ is correct.....I can deal with it. The issue will come down to work space for my toys. Ray