How high RPM on stock motor?

[5-90]

The AMC six (and probably sixes in general) seem to hit an issue with harmonics somewhere around 6000-6500rpm or so. This means "harmonics" that are bad enough to snap a crankshaft if they go too long.

Outside of that range, you're fine. If you want to get past 6500, get there quickly (and make sure your engine is balanced for it - it's a cinch it isn't right now.)

Barney Navarro ran an AMC six at Indy one year, and I'm wanting to think it was balanced to spin around 8500-9000rpm or so. The six is actually an easy engine to balance, and keeps itself smooth, but nothing can be done about the harmonic issue...

 

[poorboy_616]

SO is there an actual Rev limiter on the Renix ECU's??

I'm pretty darn sure I've had mine up arund 6 grand before.....(and yes, it does sound as if it's going to come apart at the seams at that RPM level).

 

[Wow]

SO is there an actual Rev limiter on the Renix ECU's??

No.

 

[poorboy_616]

oh boy.....

Looks like I will be watching the skinny pedal application......

 

[JJacobs]

The AMC six (and probably sixes in general) seem to hit an issue with harmonics somewhere around 6000-6500rpm or so. This means "harmonics" that are bad enough to snap a crankshaft if they go too long.

It seems like this gets mentioned often, but I've never seen any actual evidence of this trait.

 

[Goatman]

So, where's the rev limiter on an HO motor? 5200 rpm?

 

[5-90]

It seems like this gets mentioned often, but I've never seen any actual evidence of this trait.

I've not, either, but I've no particular reason to disbelieve it at the moment. I do know that harmonics can wreck an engine in fairly short order, and it can be ugly.

All of the "evidence" I've heard WRT the AMC six is anecdotal, tho, and I've not had a sacrificial engine to work with.

 

[Dr. Dyno]

So, where's the rev limiter on an HO motor? 5200 rpm?

Yes, it's 5200rpm on the '91-'95 HO and 5300rpm on the '96-'06 HO.

 

[Harlee&Tahoe]

Double post

 

[Harlee&Tahoe]

No rev limiter AFAIK on a Renix 4.0 but the tachometer redline starts at 5000rpm. A safe limit on a stock 4.0 is 5500rpm but I'd advise only running it in very short bursts if you go that high.

Redline is at 5500 on my 87'.
Although MAX RPM I've seen on my stock was 7000RPM three times:shocked: (Fcuking floormat) before I could shut down.
Thankfully I was running M1 Syn.
I don't think it would've survived otherwise.
No more sticky lifter after that!!
That's the closest I've been to sitting on a grenade.