Thread: 1JohnnyO Check HP for me.

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You seem to be figuring out HP for some of the other guy's So would you please give me an Idea the area of HP I'm in with my little Ford Engine thanks.

~ Vegas ~

Engine; 351Boss/cleveland 4.00 / 30 over deck ht.9.206 minus 1 shave?

Compression; 11.72 to 1

Heads; closed chamber 61 cc/ intake valve2.19 / Exhaust valve1.71 Roller Rockers/ guide plates
Fel - pro head gasgeet I belive comp.with steel in middle
number8347PTl

Pistons; SRW flat tops floating pins

Rods; Eagle H beam rods 5.78

Carb; BG Holley 750 double pump Mech.secondaries

Ignition MSD with Jacobs mastermind /bigwires

Intake; Edelbrock, Torker aluminum / 3000 to 7000 RPM's

Headers; Long tubes race

Cam; Erson TQ 50/ hydraulic flat tappet

Advertised duration 306
duration @ 50 235
Valve lift 545
center lobe 110
Rpm Range 3200 to 6500

Vegas. Im not a Ford guy, so what's the bore and stroke? 4" is the bore I assume, plus .030 over? If so, I need the stroke length. Also, do the flat top pistons have valve reliefs?? If so, how many cc's? If you dont know, then how many reliefs are there? The deck height as you have it doesnt mean anything, I need to know if it's zero decked? Is the piston even with the block when it's at TDC, or how far in the hole is it? Stock deck height is .025/.030 on most engines. Finally, has any port work been done to the heads?

Kurt, are you planning to run this motor on pump gas?

1JohnnyO; The bore is 4.00 and the stroke is 3.50.
the heads and block have only been shaved once so verry closed to a stock 351 Boss, the piston do have cuts for the valves.
The ports have been polished.

techinspector1 with octane boost, very little street.
I know this is not a daily driver, I have four other cars.
I was planning on running the 93 0ct. and tweeking the timming.


~ Vegas ~

OK, Peak HP = 503/6500 rpms.....Peak Tq = 440/5500 rpms. This is with pocket ported heads, that's the closest I can come to what you have done. Im wondering if your engine is a true 11.72/1 CR....did you get that figure from whoever you bought the car from, or is that the specs on the pistons? There are a lot of variables there, and if it really is that high, a barrel of octane boost isnt gonna help you. You would have to run 100 octane to make it run correctly. Just backing off on the timing isnt a fix, it just defeats the purpose of the high compression. In fact, it will run hot and very poorly if you back it off too much. On the plus side, nice numbers if they're based on fact!!

I did a little more with the CR.....with those chambers (61cc) and flat top pistons, with valve reliefs, and a normal thickness head gasket (.041), and uncut deck (.025), it comes out to 10.16/1........Even if it was zero decked, it bumps CR up to 10.80/1.

And that changes my previous post....Peak HP 471, Peak Tq 418

1JohnnyO; Those are the actual figures. The guy, Jerry that Did the machine work on my heads and engine gave Nick at Internal engine Parts all the details on the decks and chamber size on the heads after all the shaving was done. These numbers are a little higher then I wanted, but I would have had to have custom pistons made for it. This would have cost hundreds more then what I paid for the pistons I now have, $400 hundred more to be exact. Plus if I want I can throw my open chambered cleveland heads on and lose 1 1/2 points on the compression.
Belive me, I checked out all the options first.


~ Vegas ~

Not doubting you. I use a compression ratio calculator, and all you input is the chamber size, deck height and type of piston...I dont know how it could be off by a full point, but who knows? Anyhow, good luck with it.

1JohnnyO; I did forget to tell you that I am building it not buying it from any one. I have a couple of friends that run Cleveland motors and are running in the 10's,in the1/4 mile. The cam spec's are from a cam I do have, but probably won't run. It's too small for all out racing. Just wanted to get a idea of what HP, I was looking at. I really was not sure about that, I thought it would be less. The pictures I've posted are my parts, not off the internet!
Thanks for your help I do appreciate it, gives me and idea what area I'm in.

~ Vegas ~

1JohnnyO; I did'nt realize you were off full point.
I don't know my self on how to figure some of this stuff out.
The SRW forged pistons are after market and I do know that thay can change pin height' s to acommidate differant dome heights on the pistons to change compression ratio's.
But how they figer it all out, is beyond me. Techispector need's to give us some classes on it I guess!!! He'll know.


~ Vegas ~

when you mock up the engine.... do a "pour" using a Buret and mineral spirits.... this will tell you how many cc's are in the chamber when piston is at TDC and then equate that to compression ratio....
I was goin to add the cam was way small for the compression you have but you also covered that...

"Techispector need's to give us some classes on it "

Here's a paper I wrote....

http://streetmachinesoftablerock.com...opic.php?t=124