036 pro cut off head 300psi compression

[Nc grease monkey]

And took 37 pulls to get that high of compression, have a video of me compression testing if I can get it to load onto YouTube

 

[Al Smith]

I'd tend to agree although some are anal about it that a small 2 cycle gasoline engine will not suffer fuel detonation .If that were possible I'd certainly think they would fly apart like a dollar watch but they don't .I'd also agree you can overdo compression .As a rule those that run extremely fast do not run extremely long .----the life of a racing two cycle kart engine used to be figured in hours ,like under two .

 

[bwalker]

Figure out the compressuon ratio. Its not as high as you think or it would detonate..

 

[RI Chevy]

Were you able to tach it out when running this saw?
Very cool idea. What kind of studs are you using?

 

[Keith Gandy]

Figure out the compressuon ratio. Its not as high as you think or it would detonate..

Ill agree. Im not seeing being able to use a vehicle long stroked engine chart to figure psi to CR. Saws r shorter stroked and alot less time to detonate than a vehicle engine the way Im seeing it. Ive seen a few folks on these sites measure CR on saws and seems around 8.5:1 is the usual

 

[67L36Driver]

14.7 x CR = PSI

It don’t work that way.

If the above were true, the vet w/8.5:1 would pump 125 psi.

Actually it pumps 180. High lift & long duration cam to boot.

 

[wcorey]

It don’t work that way.

If the above were true, the vet w/8.5:1 would pump 125 psi.

Actually it pumps 180. High lift & long duration cam to boot.

But isn't that among the differences between measuring 2 and 4 stroke?
4 stroke calculation depends on valve timing overlap and piston speed.
2 stroke once the the piston closes the exhaust port, that's pretty much it...

 

[Nc grease monkey]

Were you able to tach it out when running this saw?
Very cool idea. What kind of studs are you using?

Stainless 5mmx0.8 thread
it wasn't as free revving as one with lower compression, I was afraid to lean it out too much so I kept on the rich side. Could of leaned it out more I'm sure. Think I may do another one just like it and actually take notes and document it properly

 

[RI Chevy]

I wonder if ARP makes studs in that configuration?

 

[Nc grease monkey]

I wonder if ARP makes studs in that configuration?

Don't know, I ordered threaded rod offline.
What I'm wanting to do is take a head cut off of a cheap cylinder and reinforce the holes in it, then machine it to increase compression. Then I can raise or lower the jug to whenever needs to be to get timing numbers desired. Haven't got that far yet

 

[RI Chevy]

Really cool work. Keep it up. Appreciate keeping us informed too! [emoji106]

 

[Nc grease monkey]

And final product look something like this

 

[RI Chevy]

Looks like it did from the factory. Lol. [emoji106]

 

[Nc grease monkey]

Need to reinforce the fins we're the studs go through, and make a jig for lathe or milling machine so can get the surface to where it will seal correctly. Not using a gasket of any sort to mate them.