Don Terrill’s Speed-Talk

Stan, We’re not building 900rpm air compressors and a good enthusiast builder can even understand that. Bob, While no one here is building an air compressor, most do want a good idle even at a lower RPM than 900, maybe even close to cranking test RPM. I remember this from over 10 years ago. When I ...

What is everyone’s obsession with cranking compression outside a specific rule set? Because almost everyone has a compression gauge and almost no one has an F1, NHRA Pro Stock, or NASCAR budget or tools to work with. Stan Stan, We’re not building 900rpm air compressors and a good enthusiast builder...

Tuner, Do you have anything actually useful to add to this thread....or is this your way of getting even. speaking of useful, so if the LSA is the most important thing, how would one design and conduct a testing program to identfy or verify that this is indeed the case? If I remember right that was...

Finally getting to grips with camshaft specs. So most important event is intake valve closing? The most important event for cranking compression tests is inlet valve closing. What is everyone’s obsession with cranking compression outside a specific rule set? Because almost everyone has a compressio...

Warp Speed, I was referring to the 19000+ cam dyno tests that D. Vizard did while contracted to Crane Cams. You have tested a few hundred? Well you have only got about 18000 to go to catch up to DV..... If we give DV the benefit of the doubt and that number of claimed test was achieved we have to r...

Eroy wrote: ↑Fri Feb 23, 2024 12:31 pm All while not owning a dyno or displaying a single, actual dyno sheet. Its impressive for sure lol

Are you referring to DV?

Stan

PS The heads for this test went done by Charles Servedio who posts here as carnut1 and was also done with a Mike Jones cam

als427 wrote: ↑Thu Feb 22, 2024 3:58 pm ok turns out the cam has 114 lsa but 110 c/l , is installed straight up , so has 4 advance . Was told repeatedly had no advance ground in , was like pulling teeth getting herberts to give me this info

So are you saying the cam was installed dot to dot and not degreed in?

Stan

so , one thing I was told , if I did a cold cranking compression test and had numbers say under 150psi it would make it a good candidate for advancing the cam ( or getting a new one). Over 160psi good enough psi for the intended street/rpm use - is this a good test to do whilst Im working on the ca...

Remember when comparing 2 cams. You can have 2 cams with the same 0.050" IVO and IVC and lobe lift and they may not have the same IVC at the valve. You also need to look at seat-to-seat duration and if the lobe is symmetrical or asymmetrical. No matter what the LSA is the IVC is based on where ...

Let's assume that we are defining the intake port coefficient of discharge as 146 cfm per square inch of flow area at the valve. For low lifts this area would be the curtain area created by the minimum distance between valve seat and the valve (which is hard to measure accurately). The 146 cfm per ...

Have you looked at your effective exhaust flow? The calculated effective velocity shifts from the curtain area to a different area. Many exhaust ports will have a velocity and CD above those limits in the upper flow lifts also. Some of the sample files the IOP program install will show this (UMPpros...

Something about that last print screen didn't look right. Sorry, I tried not to have anything but your data and the program didn't like it. The .200" numbers are wrong.

Stan

On page 1 area (curtain) is calculated using valve diameter and valve lift up until the point where valve lift is greater than .25 times valve diameter and then .25D is used. On page 2 there are a number of calculates done (one using valve diameter, valve seat angle, and valve seat width) and then ...

On page 1 area (curtain) is calculated using valve diameter and valve lift up until the point where valve lift is greater than .25 times valve diameter and then .25D is used. On page 2 there are a number of calculates done (one using valve diameter, valve seat angle, and valve seat width) and then t...

cwj1212 wrote: ↑Wed Feb 14, 2024 12:31 pm 2.02. 50 deg, 0.055", 65cfm, 147 cfm

This what our calculations show.

Stan