Dauntless V6 Compression

Who has some cylinder compression numbers on a rebuilt dauntless motor? What about someone who's got 20-30k miles on a rebuild? Over 100k miles?

I'm looking for actual compression test results.

I've got two dauntless motors and they both check out around 95-105 psi on the cylinders. Adding oil only gains about 5psi, borescope shows decent cylinder wall condition, no significant scoring can be seen.

 

Mine is at 200 to 215 psi. The engine was built by a performance shop for the previous owner. Not sure what all was done but it runs good.

 

Wow that seems pretty high

 

When I got my Jeep it wasn't running. First thing I did was a compression test. It ranged from 0-140. I had a blown head gasket and other mechanical maladies. I rebuilt the top end only as the cylinders looked decent and the engine wasn't sludged up. I changed the cam (and differing cam timing events will change the compression readings) and compression is now in the 135-150 range all over (frankly a little more variation than I'd like to see). All the valve seats were also shot. I have no idea how many miles are in this engine but I think it suffered from lack of proper lubrication. It could be lack of lead in the fuel to lack of oil changes due to wear on the cam and lifters.

 

The 1971 that was reported to have 40,000 miles. Compression with fully charged battery,clean battery cable connections,starter in good condition,throttle blocked wide open was 165 lbs all six cylinders. Non Cal. emissions /9:1 compression

 

Compression testing at it's very best is just a snap shot look at an engines internal condition..........as readings can vary based on many variables inherent during the test.......a leak down test gives a far better condition report on individual cylinders while also giving the trained eye the ability to target where the potential leak is coming from............

For me a far better reason for using a Compression test is to better understand cam timing in the since of how that relates to cylinder trapping an incoming fuel charge volume to be compressed and burned...........

 

I want to say I had similar numbers on the compression test of the renegade 1 that I purchased last year somewhere in the 100-120 range, that's at @3000 ft of altitude. I agree with Tarry that a leak down is more informative.

 

I think most know the difference between a simple compression test and a leak down test.All that was said is true, but that wasn't the OP's question.Thanks anyhow.

 

Motor purchased with unknown mileage.


Fully charged battery, throttle wide open. Compression results all averaged within 10 psi of this.


And yes, leak down testers are awesome.
Oz

 

I've done a leakdown test on the 225 in my 2a and it's about 40% leakdown all the way around. Seemed to be all going into the crank case past the rings. So it's kind of suspicious that adding oil to the cylinders doesn't raise the compression at all. But the motor still runs ok, it's hard to start when it's cold though.

Picking up a complete core motor that has similar compression to rebuild so I can still drive the 2a around in the mean time.

Was kinda curious as to what everyone else's situation was and how fast these things wear down. Supposedly the 225 in the jeepster was rebuilt 35k miles ago per the previous owner. We all know how that one goes though.....