There is no rpm point that serves as a magic threshold whereby not exceeding it ensures long term reliability, and there no one on this board can truly offer any guarantees where longevity is concerned. This is a small engine being subjected to very high power levels and revolutions, and therefore some degree of uncertainty is the nature of the beast. One does the best job he can with it (or puts his faith into someone else who promises to do his best) and hopes for the best. Just keep in mind that high loads and excessive piston speeds are especially effective at creating wear and tear.

Again, the best thing one can do is plot the optimum shift points from a dyno chart and use no more rpm than is necessary. How long it lasts depends on a variety of factors. However, remember that engines tend to run 'just fine' until just before a bearing gives way, so no one [/i]really[/i] knows what is happening internally unless they personally disassemble several typical examples at the minimum interval considered acceptable for a necessary rebuild (which is largely dependent on one's pocketbook) and subject the pertinent areas to a thorough examination.

 

heh. funny.

my "good idea" idea being simply to consult with the engine builder? actually, if *you* read this thread, from the beginning, you'll find there is no mention of RnR even being consulted on this by the original poster, or what their guidance might be. not once. not in the original post, not in any of his replies to anyone chipping in with recommendations of 8000+ rpms. here- have a another look:

now, do you see anything in there that indicates he even had *contact* with RnR about this, let alone what they advised?

now, in the ~10 minutes it took me to get around to finishing my original post (which said, basically, "talk to RnR"), RnR did indeed weigh in the the matter. good on them. ryan seems pretty consistent with the 7500 number. whats the debate?

where exactly does their "opinion" fall on your smell-O-meter?

if you really feel that "there must be some reason why he is asking it on the boards instead of straight from the builder", isn't that really implying something wrong with the info he's getting from them, or that he should look for other "opinions"?

if you know something they don't, then by all means, enlighten us. otherwise, i think you're proving my point, not debating it.

 

Yeah, your right, what was I thinking, he clearly didnt ask RnR, nor did they comment on what they reccomend....


If it took you 10 minutes to finish your initial post...... nvm I wont go there.

Scorke

p.s. 7500 falls under the moderately smelly range, think blue cheese. It's sound advice for an engine that will last for a very long time, however we don't buy evo's nor put built motors and large turbos on them so that they last for XX,XXX miles, we do it to go faster, and if max RPM limits are raised we can accellerate for longer before shifting, and we like that!

 

I've heard that Cosworth crate engines (2.0 and 2.2 Liter) are comfortable with higher that nominal revs, like 8500 - 9500. Is this true, and if so, what makes them so stout?

 

It is true, I assume the bulk of the gains in redline come from 1.Stronger rod/rod bolts 2. Valve springs and retainers.

A 2.3 can rev to 8500 on stock valvetrain, its been done before, however I personally dont want to do that(From what I have observed), the 2.0 is probably the one that rev's to 9500.

Scorke

 

9200rpm in a 2.0 isnt all that. There are guys that bring it to over 9000 for long periods of times especially in the DSMs. Shep is going over 10,500 and he never pulled his motor the whole race season. Thats with over 1000hp too!

When I do my stroker I will take it to 8000, that should be enough.

 

Ted:

"so no one [/i]really[/i] knows what is happening internally unless they personally disassemble several typical examples at the minimum interval considered acceptable for a necessary rebuild (which is largely dependent on one's pocketbook) and subject the pertinent areas to a thorough examination."

What about Blackstone labs oil analysis? I'm waiting on the results of one right now, and I plan on doing them every ~5-10K. Don't they do a pretty good job of revealing what's happening internally (bearing wear) before it all breaks loose? The E46 M3 guys (I'm a former one) have had luck with this for early diagnosis of spun bearings.

 

Main Entry: men·tal·i·ty
Pronunciation: men-'ta-l&-tE
Function: noun
Inflected Form(s): plural -ties
1 : mental power or capacity : INTELLIGENCE
2 : mode or way of thought : OUTLOOK


there is a *mentality* on this board that feels the person who built your engine is simply "an opinion of one" regarding it's proper care and feeding.

there is a *mentality* on this board that a "statisically signifigant answer" equals truth.

there is a *mentality* on this board which minimizes the knowledge gained by years of training and work in a field, and emphasizes the lowest common denominator of understanding on any topic, since that will be supported most loudly.


i understand precisely what my words mean. i am generally alone in that regard in these threads.


Main Entry: meth·od·ol·o·gy
Pronunciation: "me-th&-'dä-l&-jE
Function: noun
Inflected Form(s): plural -gies
Etymology: New Latin methodologia, from Latin methodus + -logia -logy
1 : a body of methods , rules, and postulates employed by a discipline : a particular procedure or set of procedures
2 : the analysis of the principles or procedures of inquiry in a particular field

good luck!

 

heh. yeah, that's it.

just...

can't...

type...

fast...

enough.....

 

Dude:

Not sure of your point...

"there is a *mentality* on this board that feels the person who built your engine is simply "an opinion of one" regarding it's proper care and feeding.

If one entity (shop) built your engine, it's an opinion of one entity. Opinions from more expert entities are better. Are you advocating ignoring the advice of experts like Buschur or AMS about a product like a stroker which is alsmost identical between vendors? Same, block, rods, pistons, bearings, dimension, bore, stroke, etc.

"there is a *mentality* on this board that a "statisically signifigant answer" equals truth."

Well, generally, statistically significant data is closer to the truth than non- statistically significant data. Are you advocating the use of one data point sample sizes in scientific studies? Machines (motors) are scientifically designed/engineered.

"there is a *mentality* on this board which minimizes the knowledge gained by years of training and work in a field, and emphasizes the lowst common denominator of understanding on any topic, since that will be supported most loudly."

Here you're supporting my point--gathering opinions from as many experts as possible--AMS, Buschur, RnR, Scorke :-)

 

Nothing. At any given rpm, the piston speed is lower in both of those engines than in a 2.3L 4G63. The rod/stroke ratio of a 2.0L 4G63 is 1.7. I don't know the rod length of the 2.2L stroker kits offered by Cosworth, Toda, et al, but I'd be curious to know that so we could consider the rod/stroke ratio of those kits. My guess is no less than 1.6 (e.g. 150mm rod and 94mm stroke).

A 2.3L 4G63 has the highest piston speed and least favorable rod/stroke ratio of any 4G63 or 4G64 combination, which generally means that it is the least suitable/efficient for high rpm use. Where piston speed is concerned, 7500rpm for a 2.3L is equivalent to 8500rpm with a 2.0L (25 m/sec).

Here's a quick comparison of a 2.3L 4G63 vs. my 2.3L turbo Ford for a bit of perspective:

2.3L 4G63
Rod - 150mm
Stroke - 100mm
Rod/Stroke Ratio = 1.5
25 m/sec piston speed = 7500rpm

2.3L Ford
Rod - 132mm
Stroke - 79.5mm
Rod/Stroke Ratio = 1.66
25 m/sec piston speed = 9400rpm

Consider the differences in rod/stroke ratio and piston speed.



I've never done it, but if it works, it may be a worthwhile idea. Nevertheless, the best thing to do is not spin it any higher than necessary. You'll probably find that the typical power curve for a 2.3L 4G63 w/GT35R doesn't warrant stratospheric optimum shift points.

 

Okay, for the time being I'll shift by 7500 max, and I'll set the rev limiter at 7700 for protection so I don't keep hitting it with the occasional over-rev. Thanks for all the feedback.

 

A gt35R will max out too easily on a 2.3 for my comfort. I was running 64 lbs/min at 28-29 psi. But that's just my personal opinion and setup strategy.

Without getting into the philosophical debate, I'll just add my experiences with the 2.3 in my DSM. I would set the rev limiter to 8500 or 8750, and shift at close to 8500. This was for track use. On the street, I would set the redline to 8k or 8250, and shift very close to 8k. I can't recall how many miles I got out of this setup because of all the other problems I had, like a 255LP running out of steam at the above mentioned 64 lbs/min, snapped transmission input shaft, multiple 2600s ****ting the bed, etc. I personaly have no reservations going to 8500 based on my own experience with my motors, but any higher than that I would need a long rod motor to be able to sleep at night.

This is just my own 2 cents, take it for whatever it's worth to you.

 

A longer rod will attenuate some of the side loading and improve high rpm efficiency somewhat. However, it doesn't reduce the average piston speed, which poses the most obvious detriment to longevity.

The fundamental drawback to a 2.3L 4G63 is the fact that the increase in swept displacement is achieved solely through lengthening the stroke. Because of this, using a turbo larger than a GT35R tends to create more problems than it solves, especially where a street vehicle is concerned. For a street vehicle, perhaps the only real advantage in using a 2.3L is in low rpm street flexibility with a 3076R or GT35R.

For a strict drag racer that elects to use a turbo that requires pushing a 2.3L 4G63 to the very edge of its mechanical limits, longevity isn't an issue, and finances shouldn't be either.

 

....and most serios 2.0 4g63s spin to 10k.