RPMs Are Your Friend

This last Summer season I decided to drive a 7,500 rpm engine as if 3,000 rpms were quick sand. Quess what. I was right. It took awhile but the engine no longer has any sort of emphasima. Not that I even noticed at the time. This engine is tractible like a John Deer garden tractor flat head.

But it did not seem right. It seemed to me there must be some sort of trade off if you drive a Ferrari like a truck. Which IS something mine will do. And without much complaint. [Cogitate, Cogitate, Cogitate] "Lets pretend this 7,500 rpm engine actually might benefit by one lower gear." Its not as if 3,000 rpm at 60mph were something exotic. My 1965 Corvair does exactly that. And it has done so for almost 50 years now. And I DO drive the hell out of it.

Well guess what. The 3.2 now runs like a scalded hound.

 

Hi Bell

Three thousand rpms does not put stress on much of anything. As I pointed out my 1965 Corvair has turned 3,000 rpms at 60 mph for the last fifty years. In addition, full throttle at mid rpms does not hurt anything either. Specifically, I once owned a housboat with twine 327 ci Chevies that would turn 4,400 rpms at 3/4 throttle ten hours a day and that was the LAST thing that gave me trouble.

Finally, I put a possitive displacement supercharger on my last Lincoln Mark VII 5.0l with 7 psi and I typically used full throttle many times per day not generally exceeding 3,500 rpms. [Because that put every last vehicle in my rear view mirror and was approaching felony speeds.] After 190,000 miles the car did not use oil. Did not leak oil. And did not have exhaust blow-by. I sold it because the normal systems in the car like compass heading and climate control were becoming unreliable. That car would do 130 mph at 3,000 rpm which was the speed limititer.

In addition I reviewed rebuild documents on this engine and noticed specifically not to expect cylindar bore wear that would need much in the way of top cutting. These engines have a kind of imbedded silica [?] compound that is very resistant to wear. I do not believe they have steel liners.

As for driveline wear? This transmission feels more robust then my Camaro Z-28 five speed with which I ran so many 1/4 mile burn outs I can not count them all. And the CV joints are the same as used in Testa Rossa. I suspect I could do the same sort of burn outs with this car [it has a heavy fly wheel] but the consequences of a failure would mean scrapping the car.

Eventually I may give it a try though since I won't live forever. The secret is not to hesitate. Get 4,000 rpms, nail the throttle when the light turns green and drop the clutch. Many many times on my old Vega station wagon and the Z-28. Not one failure. Tires were another matter, but THATS where you want the energy disipated.

Anyway, I simply express my opinion from decades of doing this stuff that full throttle and middling rpms do not hurt anything. Seven thousand five hundred rpms at 90F? Well. My Mondial now has an entire new clutch system including all hydraulics and mechanicals.

I now pretend the redline is 6,500 rpms.

 

It got 1.5 miles per gallon regardless of speed. And I did not actually do 3/4 throttle all that often since normally I would just idle out into Hampton Roads [Chesapeake Bay] to anchor out for the weekend, drink beer and lie about in my sailors hamock under the rear deck canope.

I lived on the boat three years and it was cheap living. The boat cost me $12,000 which is what I sold it for after three years and dock fees were less then $100 per month utilities included. Only 300 ft square living space but it was more then enough. During Winter I closed off the pilot house to conserve heat.

Pretty much the time of my life.

 

And it just keeps getting better. I have been dilligent cruising at 3,000 rpms and shifting at 4-5k often full throttle and have noticed several benefits. First of all you get actual throttle response and need not down shift. In my mountain area this lets me do routine third gear full throttle in tight corners without embarrasment.

And a couple of other benefits. First, it sounds way cool and the transmission loses the molasess feel; I suspect the synchronizers like this. And almost every time I come in from a warm run like this the idle gets better. When I bought the car the idle was a bit lumpy, had some hobby-horse to it, and the engine had noticeable surge at light throttle acceleration at 3,000 rpm.

These were not disqualifying in any way but are symptomatic of valve carbon that is absorbing raw fuel from the constant flow system. A kind or erratic absorbtion - regassification cycle. And of course carbon accumulation disturbes the breathing for high rpm. Today the idle was damn near perfect when I got home. And the car ran like a scalded hound from about 3,200 rpm on up. My pretend red-line is now 6,500 rpm but thats the sweat spot anyway. There are potential downsides, as you point out.

For instance it spins the water pump and alternator faster. It is not clear to me these are problems because my 1965 Corvair has the original alternator and I have been reving the hell out of that car for the last thirty years. The Corvair water pump never needs replacement. [Air cooled]. And of course lucky us. A water pump replacement is shade-tree mechanic operation in the Mondial. I believe it is 'Engine Out' for the later configuration. Anyway, I appreciate any and all contrarian points of view because I know damn well there are lots of things I do not know.

[Reference my posts on Alpha clutch hydraulics from last year.]

 

I understand the debate and offer this caution. In the last year I purchased two cars from the 1980s and both of them were fine in normal driving. My 1986 Monidal, of course, and more recently my 1988 Lincoln Mark VII. And in both cases I did the following test on the brakes because I live in the mountians, drive briskly, and need to know their limits.

First the Mondial. At 44,000 miles the brakes were crap. They locked up suddenly, had some shimmy, and were too sensitive. I found all that out by torture testing them. If you do not smell serious fumes you are not torture testing. But the brakes did not fail, and over the last 7,000 miles they are rather sorted out nicely. Still not my favorites but ok.

This year I bought a very cherry 1988 Lincoln Mark VII LSC with about 50,000 miles. At first the brakes seemed normal. Then I torture tested them. Essentially catastsrophic failure. I do such tests in ways and places where catastrophic failure will not likely kill me. In the end all NONE of the brake systems failed Front brakes, rear brakes and parking brake.

So I slunk back up my mountain road to carport. This very day I ordered cryogenic brake discs [$120 each]. New calipers for all four corners and new brake hoses all around. I have scores of pads from which to choose and am exploring coefficient of friction because this car, like almost all cars, has brake bias to the front.

When I am done this car will be reliable mountain burner for a thousand or fifteen hundred bucks. Thats the stopping part of the problem. One fascinating thing is the stock suspension, though not tight feeling, was neutral to mild oversteer. This is not something I ever suspected and is not like my 1991 LSC.

So I need to decide about the routine suspension parts I already bought! I paid about $600 for an entire set stabilizer bars, struts, bushings etc etc. One nice thing about American Iron. Two cryogenic brake discs cost about the same as one rebuilt Ferrari hydraulic clutch master cylindar.

And so I can screw aroung with the Mark VII in ways I can not screw around with the Mondial. For instance, a possitive displacement supercharger at 6 psi for the Lincoln cost about $2,500 and does not require any engine modifications at all. I even ran 8 psi in my 1991 LSC for about 150,000 miles. Don't even need a hood modification.

The Ferrari? Just forget about it.

 

Be still my beating heart. In my drag racing days 1st gear in my prepped Vega station wagon was burning rubber the entire first gear. True. That was about 35 mph. But I could jump any of those clogged up Chevy 350's. And of course it was in 1/8 of a mile so does not count.

What year is you vehicle? My Mondial has a flywheel like a Midieval flour mill and dropping the clutch at 4,000 rmps should not do anything but catapult the vehicle 200 ft down the track. I don't try it because failure in a Monidal is not like failure in a Vega station wagon.

I might, however, be able to match your terrain, very good though your terrain is. Ever heard of 'Tail Of The Dragon' ? Bikers from around the planet converge in order to kill themselves. Most do not kill themselves because during tourist season bikes are like mosquitos in summer.

I had the misfortune of driving the entire length in December in my Z-28 pulling a trailer. My God. The road would not kill me but close to the end of it I might have killed myself out of shear despiration after 16 hours driving. Not one single vehicle either way. And for very good reason. You go there to die.

 

When I get terminal cancer I will do it in the way I have always done manual cars. First, there is no brip-brip-brib. No not at all. There is a constant 4,000 rpm on the tach; on this car perhaps 5,000rpm would be the best. The light turns green and I symultaneously floor the throttle and drop the clutch like a hot potato. My particular car has a heavy flywheel which would smooth things out. What would happen if it did this and did not break anything is this: two very long black rubber strips all the way through first gear right up to fourty miles per hour or whatever is max first gear.

Interestingly, this does not wear the clutch at all because the very purpose of doing so is not to slip the clutch at all. Instead, you are slipping the tires. Assuming nothing breaks, and I have no reason to believe this beefy drive line would, all the energy would be transmitted to the rear tires which have strong anti-slip and lots of rear weight. The car would catapult out like an F-18 off aircraft carrier.

And the engine would be running at the hp peak for the entire trip. Done it a hundred times on American Iron. And this drive line feels even beefier then my Z-28 Camaro. Of course I would only need to do this for about 2 seconds till hitting second. And if you have rev limiter you can not over rev the engine. Don't know if Mondial has one or not. I think not.

 

bobzdoor

I agree with you on the rev thing with one caution on my part. I trashed the clutch plate at 7,500 rpm at 90F and so pretend the red line is 6,500. I suspect that failure had to do with my experiment with Alpha clutch hydraulics I suspect of destructive hydraulic resonance.

That asside, I think you are correct about all the gum up etc. After 18 months and 7,000 miles almost everyting about the car is better after making a decision to run one gear lower. Specifically, I have been assuming this constant flow fuel injector is incompatible with low revs.

This is especially true at warm up where fuel condensation is an obvious issue. I am lucky in this respect because I live on top of a small mountain and take about a minute or two to get down. I have now been doing it in 1st gear between 2,000 and 3,000 rpms by which time the engine is mostly warmed up.

Next I moderately accelerate in each gear to 5,000 rpms then hardly ever drop below 3,000. Over the last few weeks three things have happened. First, the car runs like a scalded dog from 4,000 on up, and has a bit of umph even at 3,000rmp. Second, the idle has significantly improved. If it gets any better it will have a perfect 800 rpm v-8 burbble.

Finally, and this is a bit more tentative, my warm starts seldom require more then one key turn. This was not always the case in the past but I would not bet much money on it. However, almost every drive has me running 4,000 - 6,000 full throttle and loving it. Hell. I drive an old Malibu Maxx with a sweet and refined overhead valve vvt system. It runs like a sewing machine at 6,000 and hits the limiter at 6,500.

It only has 220 hp so I use every last one of them almost all the time. Its been two years since I changed the oil so thats probably something to do in the next six months. I ran experiments on oil changes since 1984 and my conclusion is it just does not matter much. I ran the hell out of all of my cars and not one of them ever deterioriated in oil consumption or crank case blow by. One of them [5.0 supercharged 7psi possitive displacement Mark VII] had 190,000 miles.

But thats just me.....

PS: That Kenne Bell supercharger was a straight bolt on. The car never had so much as a valve cover removed. It even used the same - though longer - serpentine belt.