compression test results. Low: 122, high: 151... thoughts?

FastDriver · Mar 7, 2009

The motor was just built. I thought I found oil in the coolant, but it just turned out to be corrosion/rust from the block and radiator. When I drained the oil, I found no oil in the coolant, nor vice versa.

There were metal shavings on the magnetic drain plugs, but nothing big. That's probably normal from breaking in rings, a cam, crank and bearings on a new motor. I saw no metal in the oil itself and nothing bigger than little flakes.

The compression worked out to:

4. 144 8. 142
3. 146 7. 144
2. 150 6. 122
1. 151 5. 126

Everything was a little cooler last night when I did the tests. 5 & 6 bug me, but I haven't had time to do a wet test. All of these were dry.

Would like to hear any thoughts.

Chris

BlownFiveLiter · Mar 7, 2009

How much run time does the new engine have? Maybe it just needs a bit more time for rings to seat completely? If you're not suspecting head gaskets just yet, check your valve lash one more time. It's possible the valves are hanging open ever so slightly and causing a drop in PSI. I initially set my lash too tight and had every single one hanging open once I primed the oil pump. Once I went over them all again, it's been smooth sailing ever since.

Cobra_Dusten · Mar 7, 2009

have you run a leak down test as opposed to a compression test?

Rick 91GT · Mar 8, 2009

Cobra_Dusten said:
have you run a leak down test as opposed to a compression test?

The leak down will give you a clearer picture of what is going on. Chris what rings are in that motor? What were the gaps?

If you want to know how your bearings are doing, cut the oil filter open....

FastDriver · Mar 8, 2009

I already did. There were little metal flakes in the filter, too. Still wouldn't you expect to see them in a new motor?

I am familiar with the concept behind a leakdown test, but I don't have what I need to do it, and I've never done one. It basically pressurizes the cylinder while it's at TDC on the compression stroke and then sees how long it takes for the pressure to bleed down on its own, right? What would I need and how much would it cost?

Rick, my pistons were custom from CP, who also sent the rings and told Michael what to file the end-gaps to. I don't have the details. This was the only part in the invoice about them: "Rails (47.50), Top ring: moly HD CP piston rings (120), Second ring: CP HD (32), Oil Ring std tension for street/strip use, CP HD (40)"

Why do you ask?

Chris

Rick 91GT · Mar 9, 2009

FastDriver said:
I already did. There were little metal flakes in the filter, too. Still wouldn't you expect to see them in a new motor?

I am familiar with the concept behind a leakdown test, but I don't have what I need to do it, and I've never done one. It basically pressurizes the cylinder while it's at TDC on the compression stroke and then sees how long it takes for the pressure to bleed down on its own, right? What would I need and how much would it cost?

Rick, my pistons were custom from CP, who also sent the rings and told Michael what to file the end-gaps to. I don't have the details. This was the only part in the invoice about them: "Rails (47.50), Top ring: moly HD CP piston rings (120), Second ring: CP HD (32), Oil Ring std tension for street/strip use, CP HD (40)"

Why do you ask?

Chris

Yes, the leakdown will tell you if it is in the heads or the rings, but you should do it with warm cylinders.... I think Autozone or Advance will loan out a leakdown tester if you want to do one with out purchasing the tool.

I asked about the rings because I didn't know if you had a Hellfire top ring, which can take a little bit of time to fully seat, they are very hard. I run them in my high HP boost/N2O cars for a little extra insurance since they are so hard and strong they take all the heat you can throw at them with out flaking. I can not tell if that is the Hellfire TOP or not, I haven't had them come direct from CP as of yet. I also wanted to see if they possibly were gapless or low tension, you want a STD tension oil ring in that set-up unless you are running a vac pump.

FastDriver · Mar 9, 2009

Gotcha!

I just ran the wet test. Still don't have a leakdown tester. Maybe I'll figure that out tomorrow. I'm planning on pulling the passenger valve cover and taking a look at the rockers/lash, and then I'm going to retorque the head studs to 110/100 lbs-ft.

Then I'm going to rerun the compression check and see if that makes any difference.

Chris

FastDriver · Mar 9, 2009

I ran another dry test and wet-test back to back today, and the results were nearly the same 130 in #5 (as opposed to 125 dry), and 126 in #6 (as opposed to 121 dry). If I'm not mistaken, that pretty much rules out the ring seal as a concern.

I pulled the valve cover off with the intention of re-torquing the head studs. There's no way to get to them without pulling off the rockers, though. I'm not ready to do that yet, because I've never had adjustable rockers before. (I always had pedestal mount in the past). So, I'd like to have someone take me through the adjustment of one before I start taking them off. Plus, I wanted to readjust the rockers for cylinders 5&6 again, anyway.

A guy in my family that's been a mechanic all his life gave me some ideas to try if those don't work out. If all of it fails, I'm just gonna throw it back together and rock what I've got.

After I'm done with this stuff, I'm going to pull the fuel injectors and blast some air through them as per Patrick Barnhill's, my tuner, recommendation to ensure nothing is clogging any of them up. Then, I'm going to establish a mobile internet connection using an old laptop and go for a ride while Patrick logs in, monitors, and modifies the tune. Hopefully, we can quickly get to the bottom of why it is leaning out under boost.

I'll be hooking the vacuum straight up to the wastegate in an effort to ensure that there is no overboost. For the future, I'm ordering an AMS-1000, tomorrow.

The only thing that's still bothering me a little is that it seemed as though the car was using coolant. I don't see it in the exhaust, and it doesn't seem to be in the oil. However, the radiator became low, and the car started to heat up as a result. I'd like to get to the bottom of that issue as soon as possible. Hopefully, the heads are not weeping coolant due to the AFR "eyebrows."

I've also got some new front tires for it. I'm going with the 245/45/17 BFG KDW tires. They're supposed to be relatively sticky, and I know I don't need a competition tire up front anymore. I still have worn RA1s there now.

And that's the short-term stuff I'm currently taking care of.

Chris

Rick 91GT · Mar 10, 2009

Chris, this is straight from Ed Curtis @ Flowtech Induction

Valve Adjustment Procedure >Top
Hydraulic Lifter/Valve Adjustment
1. Remove the valve covers, and pick a cylinder you are going to set the pre-load on. Only do one cylinder at a time.

2. Rotate the engine in its normal direction of rotation (clockwise) and watch the exhaust valve on that particular cylinder. When the exhaust valve begins to open, stop and adjust that cylinder's intake rocker arm.

3. To adjust, back off the intake rocker arm adjusting nut and remove any tension from the push rod. Wait a minute or two for that hydraulic lifter to return to a neutral position. The spring inside the lifter will move the push rod seat up against the retaining lock, if you give it time to do so.

4. Twist the intake push rod with your fingers while tightening down the rocker arm. When you feel a slight resistance to the turning of the push rod, you are at "Zero Lash". Turn the adjusting nut down one half to three-quarters of a turn from that point for street applications. Use 1/8 to 1/4 turn for race applications. Lock the adjuster into position. The intake is now adjusted properly.

5. Continue to turn the engine, watching that same intake valve/rocker you just set. It will go to full open and then begin to close. When it is almost closed, stop and adjust the exhaust rocker arm on that particular cylinder. Loosen the exhaust rocker arm and follow the same procedure described before in steps 3 and 4 to adjust this rocker arm.

6. Both valves on this cylinder are now adjusted, and you can move on to your next cylinder and follow the same procedure again.

There may be some initial valvetrain noise when the engine is first fired up but once oil pressure has stabilized and the engine heats up, it should quiet right down to a normal level.

Remember that some racier camshafts will have a mechanical sound to them and will not be a silent as factory units.

FastDriver · Mar 10, 2009

Thank you, Rick. That's going to help. I've never used shaft mounted rockers before, but with the above, I think the rest is still straight forward.

Chris

Where are you located, BTW? You seem like a good dude. Maybe I'll have a chance to throw some business your way in the future.

Rick 91GT · Mar 11, 2009

One important thing is you do not want to break the rocker shaft loose while the rocker is under any tension, you take a risk of snapping the shaft. Bring that cylinder around till both rockers are loose, then break them loose.... I use a little 242 Loctite on them also.

Im in lower PA

compression test results. Low: 122, high: 151... thoughts?

FastDriver

I was uncomfortably high & wearing a helmet

BlownFiveLiter

have car, will race....wait, it doesn't run

Cobra_Dusten

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I was uncomfortably high & wearing a helmet

Rick 91GT

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I was uncomfortably high & wearing a helmet

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FastDriver

I was uncomfortably high & wearing a helmet

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