rpm limitations

[fishbatman]

does anyone know the rpm limitations to an 87-88 block? How high can you make it before things start to fall apart?

[TheVoyager]

It mostly depends on your setup. But I have heard 5,000-5,300 or something like that.

[glhsken]

The question really isn't when it falls apart, it's when does the power plunge off a cliff.

I know of NO-ONE making enough power over 6k that they shift any higher than that with an 8v. If you are shifting higher, you are not taking advantage of the cars natural torque characturistics.

Most shift a 2.2 by 55-5800 and a 2.5 from 5-5400 rpm. The stock engines are very stout pieces.

[fishbatman]

what i meant by the question, is.. is it a realistic possibility of making an 2.2 with a 9000 rpm redline (for example).
I know i can get it up to about 7500, because that's where we have our 86 jeep at, and it's running the original straight 6.

[tmef]

Quote:

Originally posted by fishbatman what i meant by the question, is.. is it a realistic possibility of making an 2.2 with a 9000 rpm redline (for example). I know i can get it up to about 7500, because that's where we have our 86 jeep at, and it's running the original straight 6.

But why would you want to? Read what Ken said in the previous post. Your power is way done by then. So to answer your quetion, I would say no. It is not realistic.

[88lebaron]

If you had an approbriate cam it could allow the power to be that high. Also you need the high RPM springs to avoid valve float (anyone notice valve float sounds kinda cool lol) and the bearings that can handle that kind of speed. Its not worth it I dont think. These cars were designed to not be like hondas (torque down low and low reving). If you want HP numbers im sure you could get the car with aprobrate cam to rev at like 7500RPM with like 200 lbs TQ and make like 285 HP but what would the point in that be? Our cars arent light and high reving HP is what gets little cars movig now 3000+lbs cars. Torque is what gets our cars moving.

[fishbatman]

i never said i wanted 285 hp, and 200 ft/lbs of torque. comparing the idea of a super high rpm motor to a honda is a cop out. just cuz it may not have as much torque as normal doesn't mean it won't have torque. realistically what i am looking for is equivalent amounts of hp and torque, at a high rpm. also having a turbo running fairly high boost will also add enough torque in it's own right. but realistically i was only looking for maybe 400-450 horsepower and relatively the same in torque. with hp that high. having lower torque shouldn't mean a thing, because there will already be a ton of it anyways.

[Shelby VNT]

I can't see anybody ever managing to get the horsepower and torque numbers to equalize in our 2.2 or especially the 2.5 liter turbo engines. To do so you would need some very very serious head porting, or better still a ported 16 valve head. If you go with an 8 valve head, a cam with more lift and duration will help, but there aren't that many readily available options for the 8 valve engines. Doing that will give you more valve over lap and your low end performance will suffer. The 2.2 and 2.5 is a large displacement 4 cylinder (large by automobile standards anyhow) and it's nature is to make more low end power.

Why try and make a peaky powerband, unless you are building a race only engine?

Quote:

I know i can get it up to about 7500, because that's where we have our 86 jeep at, and it's running the original straight 6.

Your kidding, right? Somehow I doubt that the straight six's hp is still climbing or hasn't already fallen off at that point.

[89daytonaTII]

I don't believe a 8v head can be made to flow for say 8k rpm in the first place. Also both the 2.2 and 2.5 have a longer stroke than bore, and that's not the combination for a high rpm engine. I think I remember reading somewhere that a 2.5 has a longer stroke than a big ol' 454...

when I think of a high reving TD I see a destroked engine to 2.0L (ala lebaron bonneville car), a hybrid 16v head, and lot's of research into cam selection. not a light work load...

[Aries_Turbo]

its the bore to stroke ratio that will make the power fall off even with a high flow head. the 2.5l especially wont rev high cause of the 4.09" stroke..... the piston speed will be too high. you want high revs.... you need a bigger bore than stroke.

Brian

[more_power]

I myselfwhat to make a high reving 2.2. The limitations are mostly on the top end of the motor. I wouldnt even try to use a 8valve. A neon DOHC 16valve's redline is like 7200RPM thats where im starting. a set of springs and cams maybe some ti retainersand 9 would be a posibility. And get the motor balaced.

[Aries_Turbo]

its NOT the valvetrain the limits these motors.... if you bolt on a high rpm valvetrain and a highflow head youll still make no power up on top like a jap torqueless motor. its the bore and stroke ratio that make the motor more geared for torque down low and less revs.

bore bigger than stroke = REVS

stroke bigger than bore (2.2 and 2.5l) = bottom end bliss and less ability to rev.

the 2.2 has more potential to rev than the 2.5l but its still not a 8-9k screamer and it wont be even with a high flow head.

why would you want less torque and more revs anyway.... just make a taller gearbox to match the torque.

if you want a screamer....buy a honda

Brian

[glhsken]

Quote:

Originally posted by Aries_Turbo why would you want less torque and more revs anyway.... just make a taller gearbox to match the torque. if you want a screamer....buy a honda Brian

WELL Said!!!

[GLHNSLHT2]

Go look at a Honda motor. They're undersquare just like ours Why don't they make torque and make hp?? I don't know. Why did my 2.2 like 5200rpm shifts at the track where my 2.5 with the same equipment as the 2.2 had like 5700+rpms?? I don't know that either. Maybe the fact that they're 16v with low velocitiy ports??? Not sure. But they're undersquare. Oh, and the 2.5 has a longer stroke than a 440 Mopar which has a longer stroke than that crappy 454 GM joke.

Later

Quote:

Originally posted by GLHNSLHT2 Go look at a Honda motor. They're undersquare just like ours Why don't they make torque and make hp??

Probably because they are only 1.8 liters. The B18B1 can only rev to 7200 RPM safely, the B18C1 (which has a shorter stroke) can rev to about 8200 RPM safely without the internals flying apart. The nature of a small cubic inch engine is to rev high.

I would say with the DOHC neon head with aftermarket cams you could rev to about 6500 RPM, unless you go wild with the cam and porting then maybe 7000 RPM.

Oh and longer stroke than the 440 doesn't mean anything. The 440 has a 3.75 stroke, but makes more torque than the GM 454 4'' stroke. It's all in the geometry, 440's have a good rod to stroke ratio for torque.