Just acquired a flathead motor (for 300$) and am working in a 6.0l block. With custom pistons cams and 12.5 : 1 compression. What kind of horsepower can I make on a street motor? Is 550 achievable? Or will I have to bring it to 7l or something big

 

It will run like a diesel on idle and will come apart at higher rpm.

 

With billet h beam rids and forged pistons? I think not 550 from 6l on most motors is doable as long as you get the heads flowing right. Realisticly 470 would be a solid number aswell

 

only one way to know???

finish it and put it on the wheel dyno.

dyno dont lie, people lie, get rich too

 

And suggestions on this build Ron?

 

many suggestions, gotta think about it!

my 5.3 made a best on wheel dyno(Dynojet), a bit over 350whp,at 6600rpm, flywheel hp is hard to figure,to many opinions,some kinda formula stuff.

my average was around 320-330whp, personally the mods done to the engine never showed the results i would have expected, i'm used to GMs, Chevy, Ford, mopar V8s,that make easy hp. best engines for quick power were Japanese,using basic easy mods,and a turbo.

just for ease of communication,your birthday? d/m/y/, we are many generations apart so communication can get mixed sometimes?

and judging by your posting & searching, you have already came up with some good advice, most of the older guys that have experience with Jag V12s ,do know what they are talking about.

see ya,, ron

 

Cal the flat head engines never ran high compression, there is no squish area to swirl the mix and I think you will suffer with detonation I would keep CR to 10:1.

The Broadspeed racers did not run flat heads, these cars had custom machined chambers in the heads (according to a reliable source)

The ONLY advantage to the flat heads is their ability to breath, larger valves can be accommodated. A 6.5L flat head you should be able to easily squeeze 500hp on 10:1 and be reliable and drivable.

 

I was thinking of having the slight combustion chamber put in the head like in the post I put up before. I just picked up my flathead v12 for 300$ and am gonna have the heads off by the ens of the week

 

Why not run pistons with a combustion chamber in them? It would of course be harder to obtain the CR you are after, but would provide good quench.

 

Im gonna gi with dished and possibly valve relieved pistons. I just need to find a set that will allow 11:1 and. more measurenents will need ti be taken when I get the block