I went from 3:50s to 4:56 with the stock C4 and 35s. Great setup for offroad and really I am not unhappy with them except when I an taking a long drive on the road. I feel like I need a 4th gear. I drove my Bronco to Super Celebration which is close to a 3 hour drive. I just kept it under 50MPH because of the RPMs and of course I was cussed for holding up traffic. I can run 70 but it is really turning some rpms... I drove it up to Duffs a while back and took the interstate home... felt like I was red lining it
Saturday I took a drive to Chattanooga so I just took all the back roads so I could keep it under 45 most of the time.
Still don't like that sound of the revving engine, eh Greg?
At least it seems like we've discussed it before, but I might be remembering someone else talking about it. Either way though, you're not in any danger of messing up the engine with freeway speeds and your setup. You can go much faster than 50 without fear of harm. That's roughly 2300-2500 rpm, which is nothing for these things.
Yes, you do need that 4th gear. That would be a sweet setup, but you're not currently killing anything but your ears and nerves. With your current setup, if your tires are smallish at about 33.5 or so, you're probably pushing about 3200 rpm at 65 mph.
That's based on a "rolling diameter" of 33.5" and a couple of hundred extra rpm for the C4 slippage.
These engines will run 3500 all day long and not complain with either heat, oil use, or stress. Other than on the fuel economy, and our psyche of course.
So unless yours is old and worn out, uses oil already, is not quite tuned perfectly (running lean or something that it might not like) you should be in good shape if you need to pump up the speed a bit to get somewhere.
I'm not saying you wouldn't benefit from the 4.11's or an overdrive of course. Just that you don't need to worry about your engine turning 3000 rpm.
Under some circumstances you might see the coolant temp go up 10-20° at 70mph or higher extended runs, but even that's not a bad thing unless you're already running at a borderline high temp. These engines actually like 200-210 degrees sometimes.
When I first got mine, I hated going over 55 in it. I did, because I had a tach and knew I was not hurting anything. But boy, did it sound like it was tached out!
Just changing my exhaust system changed my whole perception of over-revving the engine though. It went away 100% after getting rid of the old worn out setup for a nice average set of generic turbo mufflers.
In my case, with 32's, 4.11's and the stock manual trans, I was only at 2900 rpm @ 65 mph, but my ears were telling me it was screaming. So my tendency was to keep it at 55 mph, which was about 2400-2500 rpm. Sounded like about the max until I changed the mufflers.
After the exhaust, it sounded perfectly happy until about 3500.
Now, the benefit of the previous attitude was 17 mpg! Unfortunately I don't always have the time to spend, so getting 13-15 was "acceptable" at the time.
Just saying not to stress too much. It'll get you there and back at speed.
I wonder what the stock exhaust sounded like on a Six, with the factory 4.56 option and 28" tall tires! At 60 you'd be spinning that thing at 3400. Probably about as fast as that little engine would be able to push these things through the air.
Paul
