Max Engine RPM

[rboltz]

Reading the thread about NP200 heat, brought up a question. If my calculations are correct, with stock tires and all stock gearing, 2,500 RPM is about 45 MPH. 2900 RPM will net about 50MPH. This is a real slow turning engine compared to today. What is the rated RPM of these engines? These seem to be closer to the top end of a diesel, not a gasser.

[Team Nefarious]

The old tech. manual I have didn't list the engins red line but specifies max out put at 132hp @4000rpm, and the vehicles top speed at 60 mph.

[randyscycle]

My experience with Chevy inline sixes in stock form, seemed to be around 4,500 RPM tops. They'd just sort of run out after that, probably because of the 1bbl carb.

With the OHC and single barrel carb of a stock 230, I'd say it should be right around the same.......

[brute4c]

A stock 230 will turn 4000 rpms, maybe 4500....before trouble.

The stock setup runs about 3400-3500 rpms at 60 mph depending on actual tire size which varies by wear.

If you plug 4500 rpm's into the calc and stock gearing and tires at 34 inches, one gets:

1st gear: 12.1 mph
2nd gear: 25.1 mph
3rd gear: 45.9 mph
4th gear: 77.5 mph

Consider those DO NOT EXCEED speeds...if they can even be acheived. I have a civilian ignition, lockout hubs on the front and a 2 barrel carb and intake on my 230. The max speeds I have ever gotten the guts to do are:

1st gear: 10 mph
2nd gear: 21 mph
3rd gear: 40 mph
4th gear: approx 68-70 mph on a downhill

I wouldnt recommend these actually...they are scary...

[LuckyPabst]

That 230 has a long stroke, especially compared to the common hi-rev 4 bangers and V6s of today. Long stroke = high piston speed & low rev limit. It also = lots of torque and is great for a working truck.

Chris

[randyscycle]

For comparison, I am running a Chevy 396 V8, TH400 auto trans, stock transfer and axles with 38.5 tires and I am running 3200 RPM at 55 MPH. 45MPH is right about 2500 RPM on flat ground checked with GPS.

[rboltz]

Ok, so 2500 RPM is 45MPH so my calculations are correct. I only drove mine twice since I have it and both those times were in the very cold winter with stiff lube. Once I get this truck back together, it will be interesting to see how it does at 45-50MPH

[brute4c]

the cold winter weather here mandates about 20 minutes of driving at 40 mph and higher to ge it loose like arm weather conditions...