Well, coming from someone who presently owns a small-cube Windsor that
does rev to 7000 RPM, and also chugs around town just fine at 1500 RPM/45MPH, and spins 3.31 gears, I (personally) don't think it's overkill at all... JMHO.
It is
absolutely overkill for a street driven big block, and it would absolutely be overkill for an undersquare stroker (396, 408, 427) built on a tall deck Windsor block.. I totally agree.
But small cube, oversquare engine designs will rev freely, as long as they're built, blueprinted, balanced, and cammed correctly.
Also- I don't think the original poster is talking about wanting an engine that can spend ALL DAY at 7000RPM; but using that number as a safe redline is very do-able. (again- JMHO)
My engine HP peaks right at about 6500/6600, and the only time I wrap it out those extra few RPM's (in first gear) is when I'm doing a timed 0-60 run, so I can trip the timer before having to upshift to 2nd.
If I don't care about the 60mph time, or I'm doing a timed 1/4 mile, then I'm on the clutch grabbing 2nd, just as the needle is sweeping past 6500...
Now I suppose that if my engine suffers an early termination in lifespan, I may go back and re-think my position on this, but my little engine rev's like a turbo motor, it's making no blow by (my
oil level hasn't moved since the day I brought it home) and I love it...
So what if it doesn't make 400 HP? my best timed 0-60 has been 5.2 so far, and with stickier tires, I'm sure there would be a few more tenths to gain in there...wheelspin is still the acceleration limiting factor in my car.
I do agree that a full roller valvetrain is a critical consideration in running such an engine, and I also agree that if the original poster already has plans to upgrade from his current 302 to a stroker, then he is better off concentrating his time (and budget) toward getting his long term engine designed and built correctly, as opposed to trying to throw parts at the mystery motor he currently has...
I also agree with 90% of Lance's (CraftEngines) reply, except:
Quote:
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If you would like to turn 7000 rpm you will want to use short travel lifters, and a single plane intake. Only disadvantage to the single plane intake is that it will hurt the torque down low (1500rpm).
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Agree on the lifters, but the Wieand Stealth, and the Edelbrock PerformerRPM AirGap, are both dual plane manifolds that work well in higher RPM street engines - True that they don't maximize HP, but they
do offer a great balance of high end power, with lower end driveability... I have the RPM Air Gap on my engine.
As to all the points about having to run lower rear gears with a higher revving engine... That
totally depends on the gear profile of the transmission being used, as well as your planned rear tire circumference.
Final drive ratio (in each forward gear), assessed against rear tire circumference, is the real design point, and the rear diff ratio is only 1 of 3 factors in that calculation.
With a 7000 RPM redline (and a programmed 7200RPM rev limit), and 3.31 final drive ratio in 4th gear, my car has a theoretical top speed of 173, which is right inline with the assumption that its real (drag limited) top speed would be approx. 80% of that (or about 138-140, somewhere around 6 grand)
And since I have yet to exceed about 125, I really don't care whether it can go to 138, 148, or 173... 125 is fast enough (for me) to get a quick thrill every now and then...
I also understand that just because something works for
me, doesn't mean that it will work for
everyone... So do your own research, work with your builder, and make your own decisions.
I'm just offering one person's real world experiences running a small cubic inch V8...