Calling Mr. Cosworth Vega

[Duke W.]

Re: Calling Mr. Cosworth Vega

I have done a rod bearing load calculation through 720 degrees of rotation - the full four stroke cycle - for a high revving engine at maximum design revs.

Just wondering - has anyone else ever done this? If not I can tell you that it doesn't look like what your intuition might lead you to believe.

The difference in load between the exhaust stroke and the compression stroke at closed throttle is at the noise level. You're looking at the load delta of 10 psi times piston area compared to an inertia load of SEVERAL THOUSAND of pounds!

Duke

[Michael H.]

Re: Calling Mr. Cosworth Vega

Duke,

The last report I read on this was for a 348 (yea, I know, I'm old) that GM did in the early 60's and it stated that there was over two tons of force being applied to the piston from combustion at or slightly after the TDC point @ full throttle. Now subtract the opposite inertia load that's applied when the piston is accelerated from zero at TDC to roughly 90 MPH at about 80 degrees ATC, it's fastest point, and then back to zero at BDC in about .008 seconds at 6000 RPM. Yes, eight thousandths of a second! One hundred complete trips from TDC to BDC and back to TDC in one second. I don't know why any of it stays together. It's completely understandable why sometimes connecting rods get confused and go in a different direction.

Michael

[Michael H.]

Re: Calling Mr. Cosworth Vega

Duke,

The last report I read on this was for a 348 (yea, I know, I'm old) that GM did in the early 60's and it stated that there was over two tons of force being applied to the piston from combustion at or slightly after the TDC point @ full throttle. Now subtract the opposite inertia load that's applied when the piston is accelerated from zero at TDC to roughly 90 MPH at about 80 degrees ATC, it's fastest point, and then back to zero at BDC in about .008 seconds at 6000 RPM. Yes, eight thousandths of a second! One hundred complete trips from TDC to BDC and back to TDC in one second. I don't know why any of it stays together. It's completely understandable why sometimes connecting rods get confused and go in a different direction.

Michael

[Dave Suesz]

I had the opposit experience...

...years ago my Dad lived in Miami, so of course he had to have a boat. This boat had two 307 Chevy engine, OMC Marine, eguipped with "fuelie" heads, specially marked 'Vette valve covers, and marine quadrajets. They had seen a lot of use, particularly when the boat was new it was ocean raced a couple of years. The #1 engine developed a con rod knock in 1982. As an experiment, we pulled the plug and squashed the electrodes together. WOT on this engine was 200 rpm lower, but the knock was virtually gone. He ran it a couple of years like that, on 15 cylinders, until I built him a pair of 350s.

[Dave Suesz]

I had the opposit experience...

...years ago my Dad lived in Miami, so of course he had to have a boat. This boat had two 307 Chevy engine, OMC Marine, eguipped with "fuelie" heads, specially marked 'Vette valve covers, and marine quadrajets. They had seen a lot of use, particularly when the boat was new it was ocean raced a couple of years. The #1 engine developed a con rod knock in 1982. As an experiment, we pulled the plug and squashed the electrodes together. WOT on this engine was 200 rpm lower, but the knock was virtually gone. He ran it a couple of years like that, on 15 cylinders, until I built him a pair of 350s.

[Clem Z.]

killing the spark in each cylinder

was the "trick" years ago,to find out what bearing was "knocking" you just pulled plug wires till the "knock" stopped. the couple of times i tried this it found the correct rod. lucky i guess.

[Clem Z.]

killing the spark in each cylinder

was the "trick" years ago,to find out what bearing was "knocking" you just pulled plug wires till the "knock" stopped. the couple of times i tried this it found the correct rod. lucky i guess.