I played a little today on a twisty road (I know, I know - it's a truck...but it was still way fun - and I only saw one car for the whole 10 mile or so road....looks like I have a new way home for rush hour traffic).

I stuck the shifter in 2nd the whole time and noticed on a straight stretch that my tach was reading a little over 5700 rpm, so I backed off and went a little slower. How high can our engines safely go? I think when I've got it in the normal (D) drive position, it shifts around 5400 rpm.

My truck is an 01 supercrew with the 5.4. I've got JBA headers, a superchips flip-chip, AF1 intake, and magnaflow single out catback...bought everything from Mike - he's GREAT

Thanks

 

Hi rball5,

I'd have to know the exact code & program name on that chip to tell you the rev limiter, but normally it won't be more than 5800 rpm holding it manually in gear and flooring it like that.

We don't use anything more than a 5400 rpm WOT upshift point with a stock torque converter simply because even though a 5600 rpm WOT 1-2 would give quicker ET's at the drag strip, the stock 12" torque converter really doesn't like revving much beyond 5400-5500 rpm on a frequent basis - that's the real limiting factor, the torque converter - the engine can take more than the stock TQ in this specific regard.

I do not recommend holding it manually in gear like that - the power peaks at about 5050-5100 rpm with stock cams and a good intake & exhaust, so there's just no sense in revving it more than about 300 rpm past the power peak for best acceleration, as you'll just slow the truck down. Let it shift automatically on it's own, that is what will get you the quickest acceleration.

One other point - these factory electronic tachs are not known for their accuracy - I've seen one indicate what appeared to be roughly 6500 rpm when the motor was only turning 5400, and I've also seen the opposite. So you may or may not be turning quite that many rpms, but I just don't like then idea of holding it manually in gear with the gas floored to take it to higher rpms than what it would upshift at if allowed to automatically - there's just no additional performance reward for that additional "abuse."

Have fun!

 

Mike,

Thanks for the reply. I normally wouldn't stick it in second, I only did it to make it easier to slow down around the corners...there are only a few stretches on that 10 mile or so road that I can go fast enough to rev that high - reeeeally fun road .

I didn't get the 'freak out' reply, so I'll assume I'm not going to destroy anything by doing it occasionally - although I won't allow it to rev that high again (I backed off when I noticed it was that high).

Thanks again!!

 

The "freak out" reply - that's funny!

No, that doesn't "freak me out," so to speak, and there are times when I'll use compression braking from manually downshifting, or holding it in a gear manually when ripping thru the twisties, etc., too.

I would just keep to not more than about 5000 rpm when driving like that - more than 5400 rpm or so just isn't good for the stock torque converter. Other than that, by all means have fun taking the turns, etc.

 

Mike,

Talking about the accuracy of the tack..
I noticed the other day that my electronic readout of the tach was higher than the needle. About 200 rpm. My revlimit is 6500 rpm. Do you recall me asking about the needle hitting the stopper peg. I suspect that the continued hitting of the peg by the needle has caused the needle to slip on the shaft and now it reads low.



JMC

 

Only you, JMC - only you.

Actually, I really couldn't tell you if that is what happened, or if the digital odo test gauge mode always read +200 rpm over tach needle indication. I tend to think it was always that way.

But if that is possible, then you'd be the one to do it - Lord knows you've hit 6500 rpm many times on that motor, and your last 4.6 F-150, too!