What is the upper limit of compression ratios on street builds you have done with a small cam? 87 or 93? Custom tune or stock ECM? Steel or aluminum heads? Stock stroke or stroker?

I am considering building a dual fuel motor to run primarily CNG which is 125-130 octane, and want to push the limit on the compression I could get by with when forced to switch back to pump swill.

I ran 11 to 1 in my iron head 410 magnum stroker. 230@.050 cam and pump premium gasoline. Ran fine with a stock ECM and incredible with a tune.

I have also run 10 to 1 on a 318 magnum with a stock cam and tight quench distance and 87 octane. Stock ECM

CNG is hard to get much range in a fuel storage container, propane is much better choice.

Thanks for your input sir.

What kind of mileage were you able to get out of your stroker combo?

Was it a truck or car engine?

As far as tank capacity goes I have all kinds of room under my van so no worries there.

Tanks are purchased and sequential injection kit is on the way for cng at any rate.

My 406" LA motor - Duster, AT, 3.21 gear, AC, street car, iron heads - was right at the limit @ 9.5:1 measured static compression, on Calif 91 octane.
Cam was 214/224 @ .050, .470/.504 lift on 110 CL.
Had to pull timing out of it. Car ran great, though, and would pull 17MPG @ 70-75.
Aluminum heads would allow that CR and more.

Did you run an open chamber factory LA head with your combo? Was it set up for quench?

the stroker was in a regular cab dakota R/T I never drove easy and never bothered to check MPG

Just regular J heads.