what RPM

[Scufty]

What kind of RPM's do most of you guys turn at the top end with your s/oliers? And I guess what do you feel comfortable with?
6000 is getting pretty scary for me ?

[badrich]

My Shelby has all new top quality parts and they recommended 6200 RPM max. My rev limiter lets me go to 6000, where I get max horsepower, which is good enough for me. On the street, I never go that high. No need. Rich

[jwoodard]

When Keith Craft was doing engine dyno pulls on the engine he built for me he ran it up to 6400 RPM's. He said with a solid roller cam it would turn more RPM's, but mine is a HYD. Roller. I have my rev. limiter at 6200.

[JRoss]

I have a hyd roller with T&D rockers. On the dyno it made max power at 5800. Keith Craft recommended that I set the rev limiter at 6600, giving me some rpm room to shift. The engine has hit the rev limiter more times that I care to admit. About 5000 miles now and still going strong.

John

[Burnd]

I have a solid roller with a duration of 268@.050 and T&D rockers. My rev limiter is at 7000 but I shift 1st & 2nd with a light at 6200 (peak torque curve not HP) and run 3rd to 6700 with no strain on the motor. It flattens out between 6800 and 7000 anyway; so there's nothing to be gained. I haven't bumped the limiter yet since I put in the light and I don't have to worry about beating up my motor.

[Bob In Ct]

Just a thought - At 6,000 RPM the pistons are going up and down 100 times per second! Each valve is opening and closing 50 times per second and everything is really working hard. Is there really any reason to go to 7,000?


Bob

[Burnd]

Originally Posted by Bob In Ct

Just a thought - At 6,000 RPM the pistons are going up and down 100 times per second! Each valve is opening and closing 50 times per second and everything is really working hard. Is there really any reason to go to 7,000?
Bob

NOPE and you're ABSOLUTELY correct. And I think you'll understand in a sec. KC built the motor to spin 7 grand at the strip. I don't care about the 7k rpm's because I'm done pulling with any significance before then. I put the pill in "high" on purpose. I do NOT want to hit that limiter in any shape, manner or form. That limiter is as HARD or in some cases, HARDER on the motor than over-revving. I have more than enough lift and cam to rev within the power curve of my build and never strain the motor by simply staying within 6700. That's why I REALLY love that shift light. Last weekend; after 2 solid days of racing we're driving home from Quebec and it's running as sweet as when i got there. Nuttin Broke. (Saturday was Buick Day in the morning) Five out of 7 Buicks were major "broke" after a couple of runs. A sizeable number of the chevy guys were trying to "fix" sumpin. I made 7 passes on Saturday at Napierville Track. I made 9 passes on Sunday at Sanair Speedway. Sunday evening I drove it on to the trailer with "Nuttin Broke" and idling like a ***** cat. We drove it to a show Tuesday from PA to Jersey; still nuttin broke. Bob: I really, really love that shift light. NO STRAIN & Nuttin breaks. And I don't beat the hell out of my motor by "hitting" a rev limiter. A limiter is brutal on the motor and I don't think a lot of guys know it. That's why I have a 7000 pill in the rev limiter. It's only there for last, last resort.

Bernie

[CSX 4027]

I have heard 8000 RPM'S
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.......................once


My standard bore/stroke sideoiler with killer combo was chipped at 7200
7000 was not a problem and yes,
you don't need to on the street but, it certainly help at "The Glen" and solves any hearing problems

[DavidNJ]

This would be a great time for Barry to chime in, but I think he is working hard on his EMC motor.

There are various things that could be the limiting factor. With hydraulic lifters, flat or roller, the valve train mass is probably what kicks in first. You can only use so stiff a spring, and those 3/8" stem big block valves are heavy. Going to a solid tappet allows more spring. And you could also use a 11/32nd or even 5/16" valve stem and/or titanium valves.

Next is the bottom end. All those cast Scat cranks and rods work great until 6500-7000. But by then you are swinging around a pretty heavy piston, pin, and rod. At this point you will need a lighter piston with a smaller pin and probably lighter, stronger rods. All this is available and there are 8000+rpm big blocks running around.

Next is getting it to breath. Now with a prepared tunnel port or SOHC, that shouldn't be a problem. With an Edelbrock or Blue Thunder, even KCR or ET prepared, it will be pretty marginal for an over 7000rpm 500cid engine. The best ports flow as well as stock LS7 427 head.

North of 7000, you are probably looking at a solid roller cam. And probably a longer duration that will be noticibly rough at idle and difficult with low speed operation. And since this thread started talking about a side-oiler, I'm assuming we are talking about cross bolted caps.

After doing that, where are you going to put the engine? I think their are 800+hp Galaxies, Fairlanes and maybe Mustangs running around. But to handle that much power you will need a prepared transmission, rear end, drive shaft, axles, and with a manual trans clutch.

I think there is a picture on this site of an 800hp Cobra with a cage (and a roof), but I don't know where. Don't remember if is is a high rev normally aspirated engine or if it has forced induction.

[Scufty]

awesome answers guys ..Agreed on most points thats fior sure ..new push rods tomorrow and then whammo I hit the road again ..