Compression ratio

[Barry_R]

If folks want an opinion - - just stop fixating on DCR.

It's sometimes useful to keep you out of trouble if your combination is "way off in the weeds" somewhere.

But it's damn near useless for determining real world fuel tolerance.  It does nothing - nothing - to account for the variables in combustion chamber configuration, piston dome contours, intake port and manifold configuration and charge/flow efficiency, exhaust port and system efficiency, fuel chemistry, fuel charge cooling effects, or a host of other things.  Your 13:1 engine is gonna be a 13:1 engine at peak torque even with a cam oversized enough to murder power below torque peak.  And it'll rattle on junk fuel at an RPM where you won't hear it until the parts bounce off the pan.

90% of the folks reading this should dedicate time to good process, solid parts selection, and comparatively conservative compression choices - and not fixate on optimizing an arbitrary formula trying to find an unquantifiable 1% improvement.  I have seen and measured a +/-4% difference in peak power going from 9.8:1 and 10.8:1 - that's roughly 20 or 25 horsepower in a 445.  Does anybody honestly think that pushing it to 11.1 or some other arbitrary value to gain DCR would be worth the sacrifice or risk in a street cruiser where 98% of it's life will be at part throttle?

[blykins]

I have seen and measured a +/-4% difference in peak power going from 9.8:1 and 10.8:1 - that's roughly 20 or 25 horsepower in a 445. 

Sorry, Barry, you're not allowed to make estimations/approximations here.  The resident armchair engine builder will flay you.

[Barry_R]

I have seen and measured a +/-4% difference in peak power going from 9.8:1 and 10.8:1 - that's roughly 20 or 25 horsepower in a 445. 

Sorry, Barry, you're not allowed to make estimations/approximations here.  The resident armchair engine builder will flay you.

And I am supposed to care?

[RJP]

Frank...Stop trying to pick the fly shit out of the pepper.

[shady]

Since were are being all technical and such, flys don't shit, they puke. They have no assholes.

[frnkeore]

Sorry but, I don't eat shit 

For those that think I don't know Ford Engines, I was a mechanic from '62 - '70, in the hay day of the FE and worked on them regularly. My first FE was a 300 hp, 352, in 1963, that I put into a '60 Ford (had a 223 in it). I had 2 K code cars ('64 Fairlane & '65 2+2 Must) and a third 271 HP 289 engine. I built my LR 427 in '69, with a Chet Herbert roller cam, before that I put another 427 LR together for a friend that bought it unassembled. I was popular in my mechanic days. In '73 - '79, I built 3 Coswoth DOHC 4 cyl engines, as seen in my pictured Formula Atlantic, as well as my 1500cc push rod, Ford Cortina engine. Since then, I've built multiple 289/302's, Z20 & 2, Ka24E Nissan's. And my dad, before me, was a mechanic at a major Ford rebuilder (Meyer & Welch). I got his Snap On tool box to start (still have it) and lots of help from him in getting started.

I also a sold V-belt and timing belt drives and a water pump, of my design, in my machine shop business, in the '80's as seen by my ad in Circle track.

So, don't tell me I don't know SBF & FE engines. If you want to see some of my handy work, look in the Project threads for my Austin Healey. I'm 79 yrs old and have other interests (vintage tractors) and don't get things done as fast as I once did but, don't tell me I don't know Ford engines or what I'm doing.

[machoneman]

Frank, give it a rest. Wouldn't want Jay to kick you off the Forum for being a drudge. Can it and move on, okay?

[frnkeore]

Bob, do I have a right to post accurate info on this forum or are you uncomfortable with it?

Jay is a little more open mind than some on this forum.

Send me a PM, if you like, we can continue to discuss what you see wrong.