I already had a thread like this some time ago when i fucked up my olds 350 rocket on the german autobahn driving 100mph for like 15 minutes or so.
I bought a new engine and rebuild the original one since that.

I know the simplest solution would be a engine & transmission swap if you want (like me) to drive those speeds constantly maybe even for hours on a german autobahn.
BUT would it also be possible to keep the original engine, maybe even the transmission and modify both to be able to handle those speeds?
Im not only talking about the 350 rocket i am also talking about mopar engines like found in the 69 charger and many others.

I actually drive a Mercedes Benz 560 SEC and a 1971 Oldsmobile Cutlass Supreme and now think about buying a second late 60s / early 70s muscle/mopar car AND doing an Engine/Transmission swap or keeping the original engine/transmission and modify.
After that i will maybe sell the 560 SEC because the late 60s/70s muscle cars are exactly my thing i like the design and comfort but i also need the performance of the mercedes, so basically i want to build a car that delivers the best of both worlds.

 

you need to determine what caused the failure.

 

A steady 100 mph should be within the capability of mechanically-sound 60s and 70s engines. The difference between those engines and modern engines is that the old ones develop more heat due to higher internal friction (mainly rings).

For high speed use, you will need to monitor the oil and coolant temperatures. Coolant should stay under 95°C and oil under 110°C. Older cars sometimes don't cool well because of scale in the block, heads, and radiator. As well, substandard water pumps that are sometimes fitted for repair will cause overheating at high engine speeds due to cavitation.

To have best engine reliability, you should keep rpm lower by going to a lower numerical rear axle ratio, or installing a modern overdrive automatic or manual transmission. Lower rpm will reduce the heat generated by the engine.

As already posted, you should tell us what failed on your Cutlass engine. That will give you an indication of what to be careful of. There ar plenty of people on here who can help with failure analysis.

 

i just know that the engine needed to be rebuilt.
I did not repaired the car by myself.
i guess that one cylinder/pleul was damaged. i read that there is not much oil in the engine for example.

the goal would be to drive steady 110 mph.
there is a good shop 50 mls from my home they modify us cars i guess it might be a good idea to contact them, maybe they are able to upgrade my engine / transmission.

What do you guys think would i have to invest for the upgrade?

 

It's not the engine, it's the transmission / rearend combination. An overdrive transmission and highway rearend gears will put you very comfortably in the 100mph+. Stock Mopars and Chevys put out about the same hp as Olds, small or big block. New technology, roller cams, aluminum heads, efi, makes a world of difference now on performance and gas mileage. This website and the internet will have your Olds sucking the doors off those euro cars. Don't forget the suspension. I would love to see the faces of your fellow motorists as you cruise by at 100+. Good luck

 

I agree that for 100+ MPH speeds you need rear end gears that will reduce the engine RPM to a low level that will allow sustained high speed (MPH) operation. My car originally came with 2.56:1 gears which would equate to 3800 RPM at 120 MPH. You would likely need an overdrive transmission with those gears for sustained high speed operation, or even lower gears and an overdrive transmission in order to keep the engine RPM at a sustainable level for long term operation.

 

The problem is that with gears that will sustain those speeds, the car will be a dog on the street and no fun. Just a thought, you might consider an OD transmission and gears that will make it fun to drive under normal conditions up to 70 mph. Then get an additional overdrive like a gear venders that would allow for another gear change to get to the higher speeds while keeping the rpm's within a good torque range.

 

Even if you do upgrade the powertrain, please make sure the car can handle and brake that speed.

 

Maybe it would be a option to simply swap the transmission to a (relatively) modern one?
if yes some examples?

sure if i do that i will also replace suspension, brakes etc.

 

I would look into some LS options once the suspension and brakes have been taken care of. JMO

 

Either a 2004R, an almost direct swap or the much more work 700R4 will drop rpms with the lock up torque converter by 1000 RPM or more. The Olds 350 with the new modern low drag, 1mm thin ring pack Mahle forged pistons will help a lot, along with the new forged rods coming out. It also helps the 350 has 2.5" main and 2.125" rod bearings. Compared to the 455 with 3" main and 2.5" rod bearings, it is much more RPM friendly. Look for other motors that are known to be RPM friendly. The 3 spd Mopar transmission's are good, the overdrive versions have flaky electronics and have more issues to fix. You can adapt something like the T-56/TR-6060 6 spd manual with a 50% overdrive 6th gear to Ford, GM and Dodge motors, even big power motors. Use this calculator, it is very accurate with a lock up torque converter. http://tech.oldsgmail.com/axle_RPM.php

 

An overdrive transmission should bring the engine speed down to sustainable levels for your requirements. But you might need to upgrade the engine to be sure it is making enough mid range power to push the car through the air at 110mph. Theoretically my 88 Royale would do 140mph, but it doesn't make enough power to get there.....

Roger

 

I just want to avoid this:
I want to drive 110mph but i do not want to have a very slow acceleration especially in lower speeds.

Thats the reason why i asked if it would be a option to swap the transmission to relatively modern one, that also would have more gears so the rpm should not get to high but high enough to accelerate not to slow.

 

As much as I hate to say this, it's a perfect candidate for LS/4l80E swap.

 

Find out what the rear gears are. My 70 was no dog with a 2300 stall lock up converter, 2004R and 2.78 gears. A better converter, like a D5 factory high stall torque converter helps substantially for off the line acceleration. My 9 to 1 compression, 214/214 custom cam from Cutlassefi in an Olds 350 with headers and 2.5" X pipe dual exhaust could spin the tires a quarter of a block and got 19 mpg imperial doing 70 mph, around 2000 rpm. Hope this helps. Stupid LS would be a dog with tall gearing.

 

Sorry I disagree. I'm all for keeping Olds an Olds, but this is a perfect candidate for LS swap. LS with a simple cam swap will run circles around your 350.
Technology moves us forward. As we work, we learn better ways of doing things with better results. The LS is a culmination of that. Easier, cheaper horsepower than the traditional small block. WAY better fuel economy without giving up that gained horsepower, and the dependability of fuel injection and the benefits it brings to both of the afore mentioned.
Six bolt mains. The block extends past crank centerline, also structural oil pan creating a much more ridged design, roller fulcrum rockers, 15* valve angle at the worst, symmetrical intake runners, better ignition, better gasket sealing, better piston design, ETC.

The blocks are two to three times as strong., the stock internals are good for more power than most small block guys ever dreamed of making. They will also get far improved fuel economy, not to mention power capability. You can't argue 40 years of technology.

And I'm sure parts are much more readily available even in Germany.

not trying to be a LS fanboy, but in this case where OP wants to run 110mph+ for extended period of time, LS (with 4l80E)is a perfect candidate.

 

I have to agree with the LS option, So many benefits if you want to run 110MPH down the autobahn. It just makes more sense in this case.

 

assuming hes german and hes driving his car as a registered classic (for less tax and insurance) he will have a lot of issues swapping a modern engine in there. he might lose this status.

transmission-wise it makes it hard to see for the untrained eye that this is not the original transmission (i think) but with a modern LS engine in there you will raise some unpleasant questions on the next car check.

 

The 4L80E is very sturdy trans but has a crappy first gear and deeper overdrive gear as well than the 4L60E or 2004R. I think the 6 spd manual would be better and more fun. Well he needs a cam swap, the stock 5.3 sucks. I will admit they do get better fuel economy though. A Gen 5 5.3 is a totally different story, very impressive and fuel efficient and now there are stand alone controllers for that swap.

 

Yes this is one of the reasons i would like to keep the original engine if possible.

I like manual transmissions but not in this car.
So i would like to keep automatic.

Thanks for all your opinions and advices i think its time to contact my local shop and ask them what they think about it.
Now i have some knowledge that helps me to argue with them.

As i do not want to modify my 71 olds cutlass i will buy a second car for that.
And for that reason i need to know if i need to look for a project without engine/transmission (if i will do a engine swap) or a good condition base car to modify.

 

One thing I haven't seen is if you're going to keep the revs that high for that long (even with steep gears it'll be spinning faster than usual) - heat management is important. An auxiliary transmission cooler and an engine oil cooler are musts.
Note that most of the oil cooler setups that are readily available are horrible. Spend some time picking parts and designs there.

 

I decided to bump this one more time.
Im seriously thinking about buying a 1969 dodge polara with a 440.

So after all your informations.
Do you guys think if i would install a Transmission from a Hellcat Challenger or a new 8 speed Chevrolet Automatic
AND would improve the oiling and cooling on the engine i would be good?

Goal would still be driving steadily 110mph! (125 would be awesome)

Or would i have to do more? what?
Or do you think the only way would be a engine swap?

I hope with the 8 Speed Transmission the car would be NO Dog on the Street.

 

Michael, the 440 in a Polara would give good power and should live well at reasonable engine speeds. In the 1960s, Dodge and Plymouth muscle cars had the lowest rate of warranty service on their drivetrains compared to the other manufacturers. I mention that so that you know you will be dealing with a reliable combination from the start.

With the Hellcat Torqueflite 8HP90, you would use a rear gear around 3.00 or high 2s. With that, your first gear overall ratio would be about 12:1, which would give very strong street performance with adequate tires. The overall ratio in 8th gear would be about 2:1, which would give about 3000 rpm at 125 mph, again depending on tires.

Make sure you put in a large, capable oil cooler with a thermostat to avoid over-cooling the oil in cooler weather.

High speed use reguires upgrades to suspension, which was mentioned. However, it will also require some type of front spoiler to partially block air flowing under the car, otherwise you will have too much front end lift and steering will feeel strangely disconnected from the road.

 

Dude! I remember my friend running a full size mid seventies Mercury at 110 plus for well over twenty minutes on the daily commute to high school. I ran my 69 Torino at those speeds as well. No issues other than the brakes weren't sufficient for those speeds. Both cars ran just fine when they were sold.

 

Thank you both for your replys! I think i will go for it.

Im surprised that you did not have any issues driving 110 plus DAILY, because i needed to rebuild my engine (350 Olds Rocket) after doing that ONCE.
Have these cars been modified?

 

I have a 2017 Challenger GT with a 305 hp V6, ZF 8 speed 8HP45 auto, AWD with 3.07 diffs. I runs around 1500 at 60 mph with it's tall 235/55R19 tires. It runs in the 14's in the 1/4 mile factory and gets 35 mpg imperial highway, 20 mpg around town even in the winter. The 8 speed has the same overdrive ratio as the 2004R just a much better gear spread along with a much steeper first gear. You will probabkly need an adapter to bolt it to the engine, maybe custom made and a controller as well. Carbs like Holley and the Street Demon, a 750 with the Aerospace body would look perfect, have TPS sensors available to work with electronic trans controllers.

 

There was a problem with your engine or cooling system. From new, it would have been capable of going that speed. In West Texas in the 1960s, people with stock V8s drove around 100 mph for long distances every day.

 

So that beeing said, do i even have to change the transmission when i buy a 1969 dodge polara with a 440?
Or do you think i would also be good upgrading the cooling/oiling and making sure the engine is in good condition?

As i cant do it myself and have to pay a mechanic, it would safe me a lot of money and trouble to keep the whole drivetrain original.

 

You will need to check on the rear axle ratio. It may not be suitable for sustained high-speed operation. When built, the car was optimized for fast street acceleration--and there is no overdrive gear in its 3-speed 727 TorqueFlite automatic.

The quality of work that has previously been done on the engine and cooling system is an important factor. For example, if the same people who worked on your Oldsmobile worked on the Mopar 440, you would expect mechanical problems regardless of how capable the car was when it left the factory.

 

Yeah after what i know now, i think its time to change the mechanic.

Okay thanks for all your help, now its time to act.

 

With the optional 2.76 gears, it would be around 4000 RPM at 110 mph. With the standard 3.23 gears expect about 4700 RPM at the same speed. This assuming 225/70R14 tires which are close to the stock tire size. You can lower it more with 15" and up rims with taller tires.