How much rpm can a stock bottom end handle reliably?

Cobra4B · Aug 31, 2009

I have a 302 in my Panoz with a built top end (AFR 165s, ed curtis cam, edlebrock intake, pro-systems carb) making 314 rwhp. I have a 6500 rpm chip in my MSD box.

This past weekend out at VIR I had my new 3.89 gears in it (vs. the previous 3.50s - Ford 9" rear) and it spent alot of time north of 6000 rpms in many locations. I have my shift light set at 6k and shift there when I can, but a few places on track necessitate holding the gear.

Some are telling me the bottom end is on borrowed time spinning this high... so what's the real deal?

Dino Dino Bambino · Aug 31, 2009

The stock bottom end should be OK to 6500rpm.

Cobra912 · Aug 31, 2009

I cringe winding my built motor past 5800........but it cost me a lot of money

TechSteele · Aug 31, 2009

In a GOOD Bottom end 6K should be fine.
Personally, i wouldnt go to 6500 to often.
For me, That would be a missed shift where i fell asleep in the middle of it, LoL

Like above, think my light is set at about 56-5800 with 3:73s

Cobra4B · Aug 31, 2009

Well... looks like I'll buy a built shortblock and have it ready to go. I'm not slowing down so I'll run her until she gives up the ghost.

89stang1 · Sep 1, 2009

Cobra912 said:
I cringe winding my built motor past 5800........but it cost me a lot of money

Ha Ha im the same way!!

Some say RPMs are the killer from what ive seen once u are over 400RWHP the risk goes up, your HP isnt too threatning but your making up for it with RPMs bouncing off ur rev limiter with 6500RPMs repeatedly on a road course......................man that sounds like FUN!!! love to do that with somebody else car LOL

-Nick- · Sep 1, 2009

no one even mentioned valve - train.... wtf?

90lxcoupe · Sep 1, 2009

Cobra4B said:
Well... looks like I'll buy a built shortblock and have it ready to go. I'm not slowing down so I'll run her until she gives up the ghost.

I like your attitude

-Nick- said:
no one even mentioned valve - train.... wtf?

Seriously, i wouldnt worry about the pistons, rods, crank at all. Valve float is what will really get you in trouble here. I would have no problem pushing a stock bottom end to 6800-7000 RPMs if i had the right valvetrain backing it up.

keepinitril · Sep 1, 2009

I wondered the same thing,

I wondered the same thing how many rpms, reasonably, then on day I cranked it to 65(WHILE STILL IN FIRST!!!)
I fell off the power band, but I blew out a corvette while getting onto the freeway

but it sounds scary at 6500!!

1991notchbackLX · Sep 1, 2009

keepinitril said:
how many rpms, reasonably, then I cranked it to 65(WHILE STILL IN FIRST!!!)
I fell off the power band, but I blew out a corvette to get onto the freeway

but it sounds scary at 6500!!

I have no idea what you just said.

keepinitril · Sep 1, 2009

1991notchbackLX said:
I have no idea what you just said.

i fixed it

strtrcr50 · Sep 1, 2009

-Nick- said:
no one even mentioned valve - train.... wtf?

Looking at the description of his top end, I'd say he prob has his valve train covered.

Cobra4B · Sep 1, 2009

I have the right top end... AFR 165s w/ comp pro magnum stud mount rockers and a double roller timing chain etc.

I'm putting the 6700 pill in it for the next event so I don't hit the limiter coming out of hogs pen. Having to shift from 3rd to 4th in a turn at 100 mph isn't that great... it limits how hard I can come out of the turn. Another 200 rpms is all I need.

The rest of the track 6500 rpms works.

2000xp8 · Sep 1, 2009

Did you ever have the car on the dyno?
Not alot of 302's make all that much power past 6000rpm in NA form.

Maybe a gearing change?

90lxcoupe · Sep 2, 2009

Cobra4B said:
I have the right top end... AFR 165s w/ comp pro magnum stud mount rockers and a double roller timing chain etc.

What about springs? thats what i would be most concerned about

Cobra4B · Sep 2, 2009

2000xp8 said:
Did you ever have the car on the dyno?
Not alot of 302's make all that much power past 6000rpm in NA form.

Maybe a gearing change?

No... I just made up the rwhp figure Yes... and it doesn't fall off. The car has an Edlebrock air gap manifold w/ a pro-systems carb.

90lxcoupe said:
What about springs? thats what i would be most concerned about

AFR dual springs... plenty good for the medium lift cam we have in the car.

View attachment 247027

2000xp8 · Sep 2, 2009

Cobra4B said:
No... I just made up the rwhp figure Yes... and it doesn't fall off. The car has an Edlebrock air gap manifold w/ a pro-systems carb.

Not sure if that's sarcasm or what.
But merely stating a rwhp number without stating the rpm it makes that power is pointless during a conversation concerning how fast you are spinning the engine.

Cobra4B · Sep 2, 2009

Yes.... I was joking a bit. Here's and older dyno w/ the 6000 rpm pill in. The car was tuned further w/ the 6500 rpm pill in. Shows stock 5.0 vs. the mods we did. Stock the car was dead over 5k.

90lxcoupe · Sep 2, 2009

car sounds like a good time, any video?

Cobra4B · Sep 2, 2009

No video... never bothered with it, but here's a few pics from NASA summer slam.

How much rpm can a stock bottom end handle reliably?

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