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427w small block ford rev potential
How high can a 351w bored and stroked to a 427 rev. Im not talking a fully built race motor, but a very built street motor, anyone get them around 7000rpm, saftly. (saftly is the key word).
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The piston speed is extreemly high for that combo at that RPM. I think the cast crank would be in dangerous teritory.
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so about 6400rpm then max.
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I was told by the builder that my 427w stroker would hit 7K but that shifts at that rpm were limited. I chicken out at 6,700 - but that's pretty exciting. She's still pulling strong at that rate. You'll probably need a solid cam to get that high.
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It depends on how exotic you want to go...
The LS7 (I know it's a chevy) is a 427 small block and it twists 7 grand all day long from the factory, for over 100K miles. Use the same technology and your windsor can do the same. The LS7 uses titanium rods, titanium intake valves, sodium filled exhaust valves, light weight pistons along with a host of other light weight componants. The point is, a 427 Windsor stroker has the "potential" for a reliable 7K+ RPM capability. |
Has the motor been dynoed??
fordracing65 You have a couple of simple questions to answer,
Is the crank crankshaft and rods cast for forged?? What is the max power range of the camshaft? REV range? Why are you looking for 7,000 rpms? Are you running an aftermarket block with crankshaft support for caps? The old rule of thumb is 3-500 rpms pass max hp tops out. Here's the key question, if you are going to beat on a motor this hard you better know that it is possible for it to break and parts to come visit you in the drivers compartment. Unless you are in a titanium tub like an "A-10" you could get hurt for pushing this motor past a safe red line. What is the matter with a 6,200 rpm limit?? If you are looking to go faster speed, lower the rearend ratio. This will help lower the revs on the motor and extend the life of it. Rick L. |
Too many variables to answer that question...
For a Dart block with a 4.125" bore and a 4" stroke, good rods and crank, then yes 7000 is no problem whatsoever. It all depends on a lot of things.... |
...plus the Dart block uses the smaller Cleveland journals/bearings which allows higher rev's and lower temp's. NASCAR does the same thing.
Bill Stradtner |
The biggest drawback to using the 351w at those speeds are the bearing speeds--with a 3 in main-------
now you can get a Dart with the Cleveland main size or you can build up something with the 289/302 size---- The Dart bigger bore smaller main size with the shorter stroke can be run well past 8500 |
Undy I dont think that Ls7 would last even 10k at a constant 7000 rpm and max hp. On the road that motor will not even average 100 hp for 100k miles and at a lot lower rpm. Some times they have a hard time making a stock car engine even last 500 miles Mark
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Just my opinion but I think 6400 would be pretty high for a production block 427W.
Like Jerry says, Dart block with bigger bore and shorter stroke is the way to go. Probaly have to use solid lifters too for that RPM range. Larry |
With good quality (not exotic unobtanium) forged rotating assembly, a stock block is probably good to about 6,500-7,000, depending on load.
The limiting facter is usually the valve train. If you use the right parts, a hydraulic roller can safely run to about 6,500. Standard parts (like stock lifters and springs) lowers the red line considerably. As said above, the chevy 427 can run to 7,000 by using a lot of expensive and exotic valve train parts. |
Properly built (Forged rotating parts, roller and sturdy valve train, good oiling)
Sure it will spin 7K safely. I think the line between “race motor” and “street motor” gets pretty dam blurry when you talk about that kind of RPM. But like Rick said “Why?” Is the goal speed or bragging rights? Jerry, I like your bearing speed comment. Not often addressed. Jason |
I was going to build one and i have a $20000 budget, not so concerned how high it can rev, more concerned how big of a powerband i can have, fuel injection is where most of the budget will go, and i will be using a dart block, i know there are alot of factors, just getting a ballpark idea,
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Several people have asked "why?" and I have to go with the OP on this. I'd like my big inch small block to rev to 7K as well. Why? Because it sounds so cool!!!!:LOL:
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When I had my Cobra I had a 351 stroked to 418 and the horsepower topped out at 6200 RPM. I did hit 7,000 a couple of times by accident. Once when I hit a spot of oil and once when the posi unit broke. But that was only for a few seconds. Normally I ran it at around 6,000 RPM.
Ron ;) |
Jason
Bearing speed, among several other things, are addressed here several times a day(and sometimes nite) |
Valve float would be the limiting factor in my opinion, A poor profile could float as early as 5500 rpm's, or poor springs.
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My two cents. Engines sound wonderful above six grand. And many have profiles and a bottom end w/stout drivetrain to survive above that and still generate power up there. But alot of bad $#it can also happen above six grand...it's like climbing Mt. Everest and going above the fourth camp site into the "kill zone." You may summit and come back to brag about it. Then again, you may not. I personally build my motors to survive no higher than 6,500 and if built right they will pull to that all day long and last several cycles.
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The best advice I can give is build the engine for the purpose. There's no use in having a 7000 rpm engine (with the heads/cam necessary to do so) if you're just going to drive in stop/go parades all day.
Pick a purpose, then build the engine to make the most horsepower in that specified rpm range. |
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