Crankshaft???

backfocus · Apr 28, 2011

Does anyone know anything about Sonny Bryant Crankshafts? I am looking at buying one from someone, but done know much of anything about them.

The crank is a sonny Bryant billet steel 3.40 stroke that has rod and main journals chromed Is having the journals chromed good or bad? Also is a Billet Steel crank better than a forged or cast crank, or is Billet a common term for forged, I was thing it was a completely different type of steel. Basically the crank is in a rotating assembly that has been pieced together with Scat H beam rods and DSS Flat tops.

I would be putting it in a new Ford Boss 302 block, with High Port heads, that will most likely be seeing boost from a turbo. Although my car will only see the track once or twice a year for club event, so mostly a street motor.

90lxcoupe · Apr 28, 2011

Bryant cranks are some of the nicest around. They go for about $3000 new. The billet stuff starts as a solid piece and they make the crank from that. I read in a magazine article somewhere that a forged crank is actually stronger, but the billet stuff is lighter and i dont think you will have to worry about breaking it. If the price is right buy it and dont look back.

FastDriver · Apr 29, 2011

There are conflicting view points about forged vs. billet. However, I think all of the NHRA funny cars/top-fuel cars are using billet, as well as indy, and nascar. I personally believe that strength is not the question for forged vs. billet.

Be sure to measure the journals on the crank you're looking at. Many of them are nascar cranks that have honda 1.88" rod journals, and strange strokes like 3.34, etc... These cranks typically go for 500-600 dollars, and will not fit with the standard rods out there. You might end up saving a bunch on a crank only to spend more on rods. However, if you've really got a 3.40 stroke, 2.100" rod journal crank on your hands, then it was made for a mustang and is not a nascar custom peice.

Anyway, I recommend reading this thread over on turbomustangs: crankshaft material strength......laymens terms. "Boost Engineer" is a Ford Engineer and is extremely knowledgable overall. I think the quotes I posted are also excellent information on the subject regarding forged vs. billet. The bottom line is that a good quality forging can be a very good piece that will take whatever you can throw at it. Nevertheless, I'm very happy with my bryant crank, and I've put down 762rwhp with it. It was sold to me for $1,100 used, and is not a nascar piece.

HotFox · Apr 29, 2011

I would question on why the journals are chromed? Were the journals turned to small or ate up and to bring them back they were chromed? I hope who ever did the chrome knew what they were doing, cause if it starts pealing that will spin a rod or main in a hurry. Billet cranks are usually 8620 material and go thru surface heat treat process which I think is called nitrate. There is no real reason that I am aware of why you would need chroming as the journals after heat treat will be plenty strong. My thought would be the crank is under such stress that the flexing would cause the chrome to peal. The forging vs billet has to do with grain structure. In my case I could not afford the forging dyes to do a one off tractor I6 crank (previous hobby, tractor pulling). This is the reason I found a guy around the metro Detroit area to build a 36" long 5.375" with stroke 2.0" dia. billet crank. It is still running today turning 6,800rpms.

Scott

90lxcoupe · Apr 29, 2011

6800 rpm diesel? More pics now!

HotFox · Apr 29, 2011

Here you go Doc!
Not a grease burner. Alcohol once you work on a gas/alcohol engine you will never go back to diesel ever...diesels are so dirty yuk.

View attachment 190495
View attachment 190496

Videos....
http://www.youtube.com/watch?v=Hlv5qif_IwI&feature=channel_video_title
there area few more under
hitting the rev limiter when tractor got upset mid track
YouTube - Ed Shoobridge 3-5-11 Natural Super Stock Dekalb Eaton, OH

Scott

90lxcoupe · Apr 29, 2011

Pretty cool, thats definitly a different setup than what im used to seeing guys pulling with. How much power didi it make?

HotFox · Apr 29, 2011

Yes it is different, we run against 2.5" turbo tractors in one association. I designed the connecting rods and rocker arms. When we first built it we ran it in a dyno cell to try and tune it with a leaking head gasket and a poor fuel system the best it did was 505hp and 537ft lbs. We have come a long ways since and estimate over 600hp and 650ft lbs at 430 cid I6 with only a 300cfm cylinder head. We try to pack more in with a .860" + lift cam and lot of duration. The problem is cant drive it on the street and not a big enough following to sell your hand me down parts and make a name for yourself. Let along the non standard rules from association to association.
Scott

backfocus · Apr 29, 2011

Thanks for the replies guys. I found out more info about the crank last night. I was thinking it was a new crank, but I was wrong. Turns out it had Big Chevy journals a 2.2 it think. So he had Crankshaft Specialists in Memphis grind it down, then chromed them, they are still chevy size though, 2.1. He said the mains a normal ford size.

I am hesitant to buy and use it, as it is something I am unfamiliar with The only reason I was consider it was that I could get the whole rotating kit for $1000. Plus the pistons are just flat top -4cc and would put my compression way to high, so I would of had to switch those out as well. Since the track closed in Memphis there are a lot of people getting out of racing over there. So I am passing on the rotating assembly and just getting the new block. Time to look for a rotating assembly now. Probably going to stick with a 331 with the new Boss block.

90lxcoupe · Apr 29, 2011

1000 is not a bad deal for that rotating assembly tho

Crankshaft???

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