Max rpm for stock 3400

[indygurl]

How high is everyone revving their stock 3400?
What are the limiting factors for max rpms with these engines?

[Guest]

How high is everyone revving their stock 3400?
What are the limiting factors for max rpms with these engines?

Completely stock?

About 5200 RPM, because the valve springs are junk.

With upgraded valve springs, you can go to about 5600 or so, which is limited by the stock cam. Sometimes they will rev higher but power drops off significantly.

With an upgraded cam, upwards of 7000 RPM seems to be attainable, however, with a properly matched cam, gear set and tuning will not need to rev all that high.

[neophile_17]

I know it's well past Halloween and even Thanksgiving but I'm going to tell a terrifying story anyway.

In the confusion of a clutch swap my dad was asking me strategy questions on driving our 3400 LeMons car. What he heard was shift whenever you want the engine will magically protect itself. What I meant was explore your upshift point the computer will let you know what's too much with the rev limiter. So what happens when you mistake the second statement for the first one? You get to the end of the longest straight in 4th (overdrive) jam it into 3rd and let out the clutch. This massively overevs the engine and produces terrifying handling. Well our little 3400 has survived 8 races, about 4 hours of once a lap overeving, of this behavior, an additional 2 races with less abuse, and the 100,000 miles it spent hauling around an Oldsmobile. It's just now starting to need oil after a day of racing but it should last the 2016 season.

So the moral of the story is that this is a tough as nails engine that will stop making power well before it disintegrates.

[robertisaar]

...... that is somewhat terrifying and comforting at the same time?

i'll echo here though, the crank, rods and pistons are all okay with 7K RPM but looking at dyno graphs, you would have to have a pretty unique situation(extremely wide gearing) to see much benefit to spinning beyond ~6000 and not get more torque to the wheels via the next gear.

[Nick-G]

I ran my stock 3400 to about 6200-6500 rpms for a while when it had a supercharger on it. After I pulled it out at about 96.xxx miles to replace it with my built engine I tore it apart to inspect the internals and found the cam bearings worn pretty badly and some damage to the cam lobes.

I never looked into it any further but always assumed the damage was caused by the high rpms. I could be wrong of course but the engine was always maintained very well and I never had a reason to believe anything else was wrong with it.

[19Cutlass94]

I shift my car at ~7000 rpm's. Don't do it all the time, but sure is fun when I do.


Sent from my iPhone

[Superdave]

I had the rev limiter set to about 6K in the chips that I used to sell. On all of the dyno runs they'd fall off before that.

With upgraded springs they'll rev higher safely but like Six said they don't make any more power up there without a bigger cam.