have 347 ford with 10.to 1 thinking about going t0 12.5 to 1 engine is putting out 471hp how much hp will this add any opinions tks Butch
It all depends on the cam, heads, induction, and fuel used etc. You can actually lose HP rather than gain if you do not match all the componants.
Alex, having Vic JR heads ported and changing to solid cam, just wondering if the added expense would be worth it tks Butch
27.61 is more credible. Just enough decimal points to make it plausible. 27.613 and everyone would suspect that you're putting him on. Bob
Being that you did not give enough information for someone to plug your engine into a computer, I am going to approach this question from strictly a thermodynamics point of view. With an Otto Cycle (gasoline) engine, the thermal efficiency is directly related to the compression ratio. In this case (and ***uming a 1.4 specific heat coefficient for air), your thermal efficiency will go from 60.1% to 63.6% with a rise from 10:1 to 12.5:1, under IDEAL conditions, an increase of 5.8%. Since thermal efficiency is also directly proportional to work output (power) then you can expect a power increase of 5.8% or from 417 hp to 441 hp, again under IDEAL conditions and all things being equal. Now, there are other factors that will play into this. Mainly, the shape of the combustion chamber will change and this will effect performance. And then any other changes you may do that will effect air flow in and out, carb changes, cam timing, etc. All of this may either help or hurt. Good Luck.
bobsSS396 beat me to it but yeah, we here on the East Coast have pretty much the same answer but I came up with 27.59
FrozenMerc's math says 24, you guys saying 27 or more must be adding some snake oil to the crankcase to get those three extra ponies......
It is hard to determine from your info where you are at now...what pistons are being used, what heads, combustion chamber size, head gasket thickness, deck height. Also, what total advance are you running? You have to watch 347 for ring land location, some of the older build had problems with breakage. Small block fords love better flowing heads. If you are running Trick Flows or AFR 205's you are way ahead of the game....Great heads are the trick..... IMO I would leave the 10:1 ratio alone (if that is where you are at) as at 12.5:1 you will have pump gas issues... If you really want more power at this point, go to a 351W and stroke it to 393 or 408...it will drop right in.... Tom
Oops.... just saw you are Running Eddy heads, dump 'em for some AFR's..... that motor needs a roller valvetrain too....
I thought the answer to life, the universe and everything is 42. I have heard of people running 12.5 to 1 or higher on the street by using the government octane, I mean booze, err E85.
The snake oil only works with Cobra pistons... In the immortal words of Rodney Dangerfield: "The answer is...the answer is...4!?
It will help torque slightly more than horsepower. Also helps throttle response a bunch. Oh ya, sounds better too. Almost impossible to run on pump gas on the street. If you want more power, and drive it on the street, bolt on a plate. Nitrous works great, and 10 to 1 is ideal for a street set up. Been spraying stuff for years, if you stay conservative is nice and safe, doesnt affect daily drivability, costs $3/lb. All ya gotta do is pull some timing out, and have a good fuel system.
Without going through all the details as mentioned, normal gain per point of compression increase will be 20+ up to a point of diminishing returns. I run 15.99 (static) which is 12.7 (dynamic) with my combo and this is maximum gain. Hope this helps....
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