Rpm?

[Herr_Poopschitz]

What kind of rpm are the forged crank/stock rods good for in a 440 and remain reliable?

 

[super-bee_ski]

Holy Cow///
Good question!
"Inquiring minds want to know..."

From what I have seen and researched, the 440 does not need "High RPM" to make the power.
In fact, the higher RPM shows a de-grade at above 5400 RPM.

Peak Happens around 4400 RPM through 5200 RPM.

This of course depends on the "Builder / Mods"

Mopar Muscle, April 01, 2001

rpm Test 1 Test 2 Test 3 Test 4 Test 5 Test 6 Test 7
2600 442.2 444.1 454.8 470.2 455.7 447.9 443.6
2800 449.7 451.7 462.5 475.2 463.2 454.0 456.0
3000 456.8 462.0 472.2 488.5 474.0 463.1 473.4
3200 463.3 472.3 480.3 498.8 486.8 479.5 495.0
3300 463.5 474.4 481.6 501.0 492.7 486.0 501.6
3400 461.0 474.3 481.7 500.6 496.0 490.4 505.5
3600 456.6 471.9 476.2 497.2 501.6 491.1 517.3
3700 452.0 467.3 472.1 493.7 502.8 499.2 519.6
3800 446.9 461.7 466.4 490.7 501.3 498.8 523.0
4000 434.0 449.7 451.4 478.1 497.9 494.3 521.7
4200 422.1 435.7 438.5 461.7 490.7 487.3 518.2
4400 412.9 422.2 426.1 449.9 480.0 476.0 509.5
4600 402.1 411.3 412.2 438.0 469.2 465.7 503.4
4800 387.7 397.8 400.4 428.3 458.5 453.4 496.2
5000 375.7 383.4 385.2 410.6 441.3 435.3 482.2
5200 358.5 367.8 369.7 389.9 418.4 413.4 466.5
5400 337.2 346.8 347.7 367.0 391.4 386.9 451.9
5600 317.0 324.8 331.0 348.2 370.1 366.1 426.6

So;
This is encouraging to note that High RPMs are not needed BUT it appears it can with stand consistent 5500 RPM balsts.

Hoping for more input from other members to clear this up.

I think, in a quality build, the bottom end can handle 6500 RPM easily.
A "WEAK" spot would be the Hydraulic Lifters.
That is why a set of Roller Rockers would be recommended.

 

[Furyous]

I know you are worried about the crank and rods.. but if the valve train is not up to par it will fail first..

A good head will need more RPM's.. Stock motor stock head stick to 5600 rpm and live a long happy life.

 

[theman440]

I run a stock steel crank and fully prepped "LY" rods. Been shifting it @7000 RPM for years.

 

[Herr_Poopschitz]

I run a stock steel crank and fully prepped "LY" rods. Been shifting it @7000 RPM for years.

Aftermarket balancer, girdle, studded mains, etc?

 

[theman440]

Aftermarket balancer, girdle, studded mains, etc?

All but the girdle.

 

[Cranky]

Shifted at 68-6900 and crossed the stripe at 7300 using a stock 440 forged crank, Hemi rods, light weigh pistons, stock type main cap bolts running high 10.60's for over 300 passes and no girdle. A main valve spring finally gave up the ghost on the last race of the season but the inner spring held onto the valve. There was some damage but nothing major. I knew the springs were getting weak but it still ran the number and was just trying to make the last race before teardown.

 

[dvw]

Assuming you're starting with decent parts correct prep and proper oiling it all comes down to piston weight x rpm. The cranks themselves provide good service. Stock pistons have ( I believe) the highest compression height of any american V-8. All that height means one thing, heavy. My general rule of thumb has been 6500 with light replacement slugs. Will they go higher? Sure , how long? Only time will tell.
Doug

 

[theman440]

I'm using lightweight Arias flat tops with .940 tapered floating pins. Much lighter than stock.

 

[Dennis H]

Pedestrian here, my warmed up 440 is about 500 at the crank. Chassis Dyno says it stops pulling at 4850 and I really don't care. It's in the basement.

 

[Herr_Poopschitz]

Thanks, that helps. I've been in touch w/ Dave at Crower and he spec'd a cam for me for my 'stock(ish)' idle req't...shift at 5800, redline around 6300 based on my assumed max RPM...he hinted that I might be leaving quite a bit of power on the table and told me to get back w/ him if I was willing to spin it more...but I wasn't sure what these things are capable of. I might see what he comes up w/ if we add another 500 rpm to it...

 

[67 B-body]

Depending on your camshafts lift and duration profile, you might not get that kind of RPM with a Hyd setup.....
The faster lobe ramps can cause a very unstable valve train on Hyd lifters...
I would go solid "Flat tappet, or roller" if I were you....

 

[Herr_Poopschitz]

Depending on your camshafts lift and duration profile, you might not get that kind of RPM with a Hyd setup.....
The faster lobe ramps can cause a very unstable valve train on Hyd lifters...
I would go solid "Flat tappet, or roller" if I were you....

Yeah, unfortunately I don't think there's been a lot of Spintron testing on BBMs.

I've always been open to using a solid roller if need be. We'll see.

 

[Cranky]

The stock LY rod can take a lot of punishment if prepped and you use a light weight piston. Even the 6 pack rod will do the same in stock form but only with aftermarket high strength bolts and can handle heavy pistons but I prefer to have them heavily massaged. IF you can do your own rod polishing work, then it can be cheaper but if not, aftermarket is the way to go.

 

[dvw]

It all multiply's. Pistons are to heavy. Then aftermarket rods are available for not much more than rebuilding stockers. Aluminum heads make more horse power. A longer stroke more torque. Now the stock block is at the limit. Where do you stop? If I was building a street 440 it would use the lightest reasonably priced pistons that were available. Then weigh the cost of new vs rebuilt rods. I wouldn't hesitate to use a stock crank. 440's make reasonable torque with heads that don't support high RPM. Use that torque to your advantage and don't spin the engine beyond 5500-6500, depending on the head/cam choice.
Doug

 

[Mr B Body]

My brother's 440 .030 over forged super heavy TRW pistons, .590 cam, lightly ported 915 heads 12.5:1 compression), stock rods, stock crank (reconditioned rods), all balanced. Stock balancer. Turns 6800 on every pass. Has over 300 passes on it and two passes with N2O bouncing off the 7K rev limiter (we didn't do that the PO did). If everything matches up, it will be just fine. No girdle, no studs. It does not even have a 1/2" pickup in it. We have checked the bearings twice. Once when we put the engine in the car and when we took the engine out of the almost 100 passes later. Both times the mains and rods looked fine. The car made 393 RWHP, so it was not a slouch.

 

[Cranky]

My brother's 440 .030 over forged super heavy TRW pistons, .590 cam, lightly ported 915 heads 12.5:1 compression), stock rods, stock crank (reconditioned rods), all balanced. Stock balancer. Turns 6800 on every pass. Has over 300 passes on it and two passes with N2O bouncing off the 7K rev limiter (we didn't do that the PO did). If everything matches up, it will be just fine. No girdle, no studs. It does not even have a 1/2" pickup in it. We have checked the bearings twice. Once when we put the engine in the car and when we took the engine out of the almost 100 passes later. Both times the mains and rods looked fine. The car made 393 RWHP, so it was not a slouch.

Next time you have the engine out for a refresh, check the block main cap fits and look for evidence of cap walk. Although you don't want any, it's hard to avoid it when you are putting that much stress on the block. Mine showed signs of it when I tore it down....

 

[Mr B Body]

Next time you have the engine out for a refresh, check the block main cap fits and look for evidence of cap walk. Although you don't want any, it's hard to avoid it when you are putting that much stress on the block. Mine showed signs of it when I tore it down....

We did look for that when we first checked the engine (mainly because we were worried about the nitrous passes), we think that there were more than just two, but we did not see any cap walk. We did not look for it when we checked bearings the last time. That engine has 60 psi oil pressure when at hot idle (it buries the gage when it is cold (50-60 F)). If I remember correctly it did have ARP main bolts in it (thankfully they were not factory bolts).

The engine we replaced the 440 with is a 520 with Ross pistons and I think Compstar rods (whatever Muscle Motors uses), ported 440 source heads, same cam and it pulls much harder (even at high RPM), but it likes to shift at 6300, but we still have the 7K chip in it. I know that engine has ARP bolts (no studs, no girdle) and it has about 100 passes on it and about 8000 hard street miles on it, but it has not been out for a checkup. The 520 makes 495 RWHP in the exact same car as the 440 was in.

 

[moparpoor]

I run LY rods in my 64. Shift 6500 to 6700 just depending. I run a factory crank that has been lightened, ly rods with good hardware and bushed for a floater, and kb pistons. Everyone was you cant spin those rods like that or those pistons!!!! Blah blah blah!!! 4 years later and many trips past 7000rpm running down some blow heart with his eagle stroker kit that makes 700hp with my factory junk!! Haha lol!! I say enjoy what you have and don't be afraid to rev it a little!! Keep it below 6500 and it will live many years!

 

[Moparbilly]

First up, 440's have a tendency to pull a bunch of oil to the top of the engine at higher rpm. So increased oil capacity is my first mod if pushing beyond 5500 on a regular basis.

With a stock port window head, heavy (Stock or TRW) pistons, and a mild cam, you will probably find anything over 6k to be waste of time anyway.

Big heads, roller cam, nitrous.. it's best to upgrade to a lighter weight piston, then 7K-7250 is not unheard of.

My theory is the stock crank and rods are nearly indestructible and will last forever in an NA motor without detonation, but, I'm a nitrous addict, so eventually I get greedy and break stuff!