TR2/3/3A TR3 cruising rpm

[emmett1010]

Hello everyone;
While trying to decide if I truly need overdrive, to do extensive cruising, it occured to me that I need to determine the upper cruising RPM speed, as this will determine how fast the car will comfortably cruise at.
What is a reliable rpm to run a stock tr3 on several 400 mile day, consecutive trips.
My engine is totally rebuilt, great oil pressure, idles perfect, starts instantly.
I'd love to get some other peoples' experience/opinons.
Thanks, Emmett 1010

 

[Andrew Mace]

A stock, non-OD TR3 -- according to all the books -- runs 1000 rpm for every 20 mph in top gear. I can't see any reason at all why you couldn't run <span style="font-style: italic">at least</span> 3500 rpm (approx. 70 mph) day after day -- maybe quite a bit more, even!

 

[donbmw]

Emmett

When I go in my TR3 I will run anywhere between 3000 to 3500 RPM's all the time.

Don

 

[NickMorgan]

70mph used to be 3500 revs and I ran the car like that for about ten years. No problem at all running at that. I have since fitted overdrive and not it is sitting at about 2900 at 70mph. A little more relaxing.

 

[Geo Hahn]

I too run 70 mph on the TR3 w/o OD. Same on the TR4 before OD, have now added OD and feel better about cruising at 75-85 all day. I don't you'd be thrashing the engine doing that speed w/o OD but it seems much kinder & gentler to do it at the reduced RPMs the OD delivers.

 

[vivdownunder]

Apart from reduced engine/gearbox wear with an O/D, a recent comparison between two TR3A's on a run together starting out with full tanks, yielded an interesting fuel use comparison. Overdrive car took $47 worth but the non O/D 3A took $54 to refill, so the non O/D car's fuel cost was plus about 15%.

Of course it still takes a lot of miles to recoup the O/D retrofit outlay.

More than anything to do with expense, as others have described, the O/D car is just so much more relaxing to drive over long distances. I've on occasions ticked off 750 miles in a day, with as low a stress level as you ever get in a TR. Try and get a drive of an O/D car and you'll see what we mean.

Then there's the fun factor of third/third overdrive/back to third at the flick of a switch between street corners. The very essence of a TR...just can't beat it !.

Regards,

Viv.

 

[TR3driver]

I'd have to agree : although OD is not essential for cruising at any legal speed (in the US), it sure is nice to have.

I've driven my relatively stock TR3 motor at 4500 rpm for hours at a stretch with no apparent ill effects ... other than the usual toll on the driver from vibration, noise, etc.

 

[TRcheologist]

I just came off of a couple hundred miles in a non-ovedrive car, averaging 3200-3500 rpm. The oil pressure was consistent at roughly 50-60 lbs, the temperature was pegged at 185 degrees (ambient was around 85 degrees), and I averaged 24.5 mpg. My 3A runs a 2.2 litre, fast-road cam, an oil cooler, and tubular manifold. Gearing is stock. No mechanical difficulties whatsoever.

I was running with the top up, and there's a fair amount of harmonic racket from the soft top frame at 3100 rpm. It quiets down at 3200.

I stay off interstate whenever possible - I don't want to be a semi's BRG speedbump - and the 70-75mph at 3500 is more than sufficient for state routes. If I was doing more long-haul interstate driving I'd look at overdrive or the 5-speed conversion.

 

[billspit]

If this was a Spitfire, there would be no question. I once had a TR3 with OD. It was wonderful.

 

[TR3AD]

Let your engine relax. Treat yourself and install the overdrive, especially if you are cruising on the highway. A nice indulgence. My experience is 70mph non-overdrive at 3500 RPM, relaxes to 2900-3000RPM in overdrive. No engine likes to work harder than it needs to, right?

 

[gsalt57tr3]

If you can't find the overdrive, or don't want to go to the expense, go for the Toyota 5 speed. I'm running about 2800 rpm at 70 mph.

And if it ever breaks, a replacement tranny will be less than $500.