What's your RPMs?

[DrewTX]

I think 6500 rpms is as high as I've ever gone....anyone ever close to 8,000 on most tachs????? whats up with 10,000 RPM tachometers????

 

[mmissile]

Shifted the Aspen hemi at 8K... the other cars[hemi] are at 6.5K and 7.2K, respectively. Lots of race engines go 10K.
Jeff at Modern Cylinder Head[RIP] told me I should have been running the Aspen up to 8500. He said it was built to do that all day. 8K was fine by me.

 

[cr8crshr]

Mine is 33 and a third....Man that sound it makes is sweeettttt!!!!!cr8crshr/Tuck

 

[Cranky]

Shifted at 6900 and crossed the stripe at 7300. One time I drove it out the back door just to see if it would still pull but I got skeert once I saw it going past 7600 and still pulling strong.

 

[66Satellite47]

In my bracket days, 7000 with my 440's, my first low deck 440 went 7400 routinely, 7200 with second low deck. I would not consider those levels again. You hurt parts in a big block above 6500. I'm going to stick to 6500 with my new motor.

 

[MoparMitch]

Broke some 383's at 9000 .... When I was 17 !!!

 

[Dennis H]

Chassis Dyno says no more juice after 4850. No need to go upstairs.

 

[Budnicks]

They are limiting NHRA P/S, T/F & F/C to 10,000 RPM now
they were all regularly exceeding that last year...

The valve-train Induction & Ignition
really dictates how much RPM can be made
the bottom end & quality of parts tells you
how many times & how long it stay together...

"Mostly stock" parts Wedges BB or SB 5500-6200 would be the max
with any longevity, that's with better valve-train & induction
or ignition too, OEM doubtful for most, with very few exceptions
the heads camshaft & valve-train aren't designed to go much past 5500

My old 526ci {later 540ci} Top-sportsman engine
would spin to 8800-9000 even make power still {not fall on it's face}
nothing in it was really a OE Mopar part anymore either
except the block casting...
BB valve spring killer,
0.850"+ gross valve lift +0.0100 longer valves & beehive springs
440cfm intake flow, Hogan sheet-metal intake & split Dominators
Callies crank, Oliver rods, Venolia pistons Child & Albert rings & Bearings
4 bolt splayed Billet main caps, ARP Hardware studs everywhere

My current 479ci 6bbl is good to about 6200rpm,
it'll pull past that easily,
but doesn't make any power beyond that point,
peak torque is more like 5600rpm,
above 6200 it just more likely to hurt parts & noses over,
makes less power/torque, so why spin it over that...


Usually with a Mopar wedge you'd run out of port design 1st,
not designed for those RPM's

IMO Most highly modified & ported {fully worked heads}
wedges about 7500 would be max,
of course depending on valve-train & heads capabilities
if the lower end stays together,
with good internals & really good hardware/studs, rod bolts etc.
maybe
an aftermarket block, 4 bolt splayed mains,
a girdle, thicker main webbing,
&/or 6 bolt Hemi style mains,
lightweight aftermarket crankshaft & rods/pistons,
are all mandatory pretty much past that point

Hemi's, mainly full race prepped engines have been doing it for 50 years
Sprint Car or Cup engines do 9000+ regularly for hundreds of miles now
depends on the parts, cylinder-heads/Valve-train are an integral part

There's a lot of BS #'s alleged {lies} over the years too....

 

[NOSTRT980]

like DrewTX, I don't go over 6500 rpm even if the motor is built for more. I don't want to be breaking parts and I do want it to last more than a season. I like to over build just to be sure. I am not talking thousands of dollars over but maybe a better rod then you would first think of using.(rod stress)

 

[66Satellite47]

I repeat, you can go 7000 plus but parts breakage is certain, I've been there. 6500 with most BB combinations will give the power & durability.

 

[747mopar]

Mines a cruiser but I shift it at 6,000 rpm.

 

[mr. b]

when I run mine hard I shift it at 6,000 but it also has eagle rods and je forged pistons

 

[Cornpatch MO]

Chassis Dyno says no more juice after 4850. No need to go upstairs.

What engine combo would that be? .................................MO

 

[Darthomas]

When the hydraulic lifters float at 5500, the 727 immediately knows what to do.
I am fine with that.
And the engine stays together for many many years without worry.
The original design has a large safety factor.

 

[66Satellite47]

I can say I had one instance when I looked at the tach & saw the needle at 8400 RPM as the motor was sputtering. Broke many valve train parts. Even ground several lobes off the cam. NO GOOD! I'm committed to 6500 RPM now.

 

[Dennis H]

What engine combo would that be? .................................MO

Don't have the recipe handy. Dyno was before NGK's, cut outs, and MSD work. Rev limiter chip at 5 grand. I prefer it in the basement anyway and would keep the exact specs next time.

 

[66Satellite47]

5000 RPM, interesting.

 

[NOSTRT980]

can I chime in here. we are talking RPM's here and no one has offered the rear gearing that goes along with RPM's and tire size that gets us to the MPH that we all want. should I start a new topic for gears used and tire size for MPH?

 

[Dennis H]

can I chime in here. we are talking RPM's here and no one has offered the rear gearing that goes along with RPM's and tire size that gets us to the MPH that we all want. should I start a new topic for gears used and tire size for MPH?

Street? 2150 RPM @ 72 MPH. TKO 5. 3:54 Dana. 14 front. 15 rear. Almost like having the 833 with an extra gear.

 

[oldbee]

Way back i ran 6500 shift points with magnafluxed rods & the last racing season one let go,even with AARP rod bolts.