Which Mopar engines breathe well enough to make use of 7000+ RPM?

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MRGTX

MRGTX

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I think it goes without saying that Chrysler has provided many of the absolute best engines ever made, especially when talking about performance engines.

That said it seems like they're often designed to make their power down low in the RPM range...which is almost always more useful for street engines, can be put to excellent use on the drag strip too...but it is still a different experience than what you might get in something like a Boss 302 or a '69 Z/28 where you can zing the engine well past 6,000 RPM, keep making power and not punch a connecting rod through the side of the block.

Sure, having to wring an engine's neck to go fast is not always the fastest way to make power but it sure is a hell of a lot of fun.

Which Mopar engines do the best job of this kind of performance? The 340 4bbl and 340 Six Pack seem to be the best candidates but in stock form, both of these motors make their peak power in the mid 5000 RPM range. Still pretty damn good but it's a long way from being useful at 7k.

Has anyone build a Mopar engine to rev like this? Can it be done?
Are the Gen 3 Hemi engines candidates for high RPM build?
 
Mopar engines were more for torque than horsepower. The Chevy guys just dream of engines with a over 6" rod. LOL You don't need a lot of rpm to develop torque. It's all in the heads.
 
The faster you spin it, the closer it is to coming apart. Why rev it if you don't have to? Mopar under-rated their engines. Build a second gen Race Hemi if you want rpm.
 
Demonic said:
The faster you spin it, the closer it is to coming apart. Why rev it if you don't have to? Mopar under-rated their engines. Build a second gen Race Hemi if you want rpm.
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3rd. :poke::lol:
 
I have always taken stock 340 up past 6000. Some stayed together for a long time . Some couldn't take it once. Everyone I put a hole in was a 4spd car shifting third with steel mounts. Always number 7 or 6 right behind the mounts? I think the strongest that i have owned at high RPM's were the 383's Them dam motors took a beating. I had many RR's and Bee's. After a couple drinks back in the 70's I would try and blow them up. Hold some flat to the floor with the clutch in for a couple seconds and then let the clutch fly and pull second as soon as the car would leap.

The GTX's and R/T's 440's couldn't take that. I would put the Dana and the 18 spline in the 383 cars add a solid lift cam and you would have a indestructible carnival ride .

Yeah I was stripping B's back then I was hard on them and used the parts myself. Back when street racing was fun when they didn't have radials. If you didn't have slicks on you didn't stand a chance making money. Steel rims with Cheater slicks was the sly move.
 
Like he said, 383 or 400 with high compression, solid cam, and a tunnel ram.
 
In Trans Am where the Boss 302 and DZ302 were used, Mopar had a destroked crank to make a 340 be ~305cid. It probably saw 7K a lot with TA or W2 heads.
 
Not really what you are asking, but....
In preparation for the Daytona Compact Car races, Chrysler ran the 170 Hyper Pak engines to 7k on the dyno. Never have seen any dyno reports showing torque numbers, but they did it.
 
Oldmanmopar said:
I have always taken stock 340 up past 6000. Some stayed together for a long time . Some couldn't take it once. Everyone I put a hole in was a 4spd car shifting third with steel mounts. Always number 7 or 6 right behind the mounts? I think the strongest that i have owned at high RPM's were the 383's Them dam motors took a beating. I had many RR's and Bee's. After a couple drinks back in the 70's I would try and blow them up. Hold some flat to the floor with the clutch in for a couple seconds and then let the clutch fly and pull second as soon as the car would leap.

The GTX's and R/T's 440's couldn't take that. I would put the Dana and the 18 spline in the 383 cars add a solid lift cam and you would have a indestructible carnival ride .

Yeah I was stripping B's back then I was hard on them and used the parts myself. Back when street racing was fun when they didn't have radials. If you didn't have slicks on you didn't stand a chance making money. Steel rims with Cheater slicks was the sly move.
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Some go and some blow! Those 383's have a shorter stroke than a 350 Chevy. They are quite an engine if built right.
 
MRGTX said:
I think it goes without saying that Chrysler has provided many of the absolute best engines ever made, especially when talking about performance engines.

That said it seems like they're often designed to make their power down low in the RPM range...which is almost always more useful for street engines, can be put to excellent use on the drag strip too...but it is still a different experience than what you might get in something like a Boss 302 or a '69 Z/28 where you can zing the engine well past 6,000 RPM, keep making power and not punch a connecting rod through the side of the block.

Sure, having to wring an engine's neck to go fast is not always the fastest way to make power but it sure is a hell of a lot of fun.

Which Mopar engines do the best job of this kind of performance? The 340 4bbl and 340 Six Pack seem to be the best candidates but in stock form, both of these motors make their peak power in the mid 5000 RPM range. Still pretty damn good but it's a long way from being useful at 7k.

Has anyone build a Mopar engine to rev like this? Can it be done?
Are the Gen 3 Hemi engines candidates for high RPM build?
Click to expand...
The way engines were delivered as stock and what can be done to them afterwards are 2! Totally different worlds. Some manufacturers made engines that were good power makers at 6K OOTB. Some don’t have to!
Getting a small block to rev safely past 6600 is minor oil mods and past 6900/7000K make requires a little more attention and effort.

Im not so sure about the Ford oiling system, but the Chevy can go very high in the rpm range as delivered and stock.

When it comes to making an engine make power at said rpm, the first things is attention to the oiling system so it will live and then the overall engine package. It boils down to getting the air in and out as effectively as possible without restriction.

Then it is camshaft specs and valve spring control.
If you get the valve springs to control the valve on that high lift long duration camshaft your in good shape.

MoPar engines have small ports vs there CID when you compare them not only to other stock engines but they show a massive deficit on the race side of what needs to be done.

Also, do so be reminded that just because you can rev an engine to engine 10,000, doesn’t mean your making any lower up that high. My Chevy friend tried to brag about spinning his small block to 10K ...... and I told him just what I typed above. Hey! I can’t help it if he got mad as hell at me. It was his *** he put on his shoulders. Not me.

Bottom line, it’s all about the package and a good balance of it coupled with quality parts and machine work with a great oiling system, yea, you’ll get there!
 
My Gen 2 472 Hemi hits 7000 rpm with ease.
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Stock for stock never seen a 302 beat a 340. My 383 road runner beat my friend 68z easily. My 340 see's 7000+ all the time. Stock bottom end with forged pistons.
 
steel crank 340, light forged pistons, ported heads, double valve springs, balanced, blueprinted, solid lifters = 7000 every day
 
aaronk785 said:
Stock for stock never seen a 302 beat a 340. My 383 road runner beat my friend 68z easily. My 340 see's 7000+ all the time. Stock bottom end with forged pistons.
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With no drilling of the oil passages or other work done?
Lucky you as I see most every guy try this and cry later on the engines oiling failure. 7K or even north of 6600 I would not ever try again without paying some attention to the system. I paid tuition that way once and only once when I was young and dumb.
 
My 340 seen 7600 all the time street or strip that's what it liked.

I will add : with a stock bottom end also!
 
Demonic said:
The faster you spin it, the closer it is to coming apart. Why rev it if you don't have to? Mopar under-rated their engines. Build a second gen Race Hemi if you want rpm.
Click to expand...

You're absolutely right...but if this is your argument, why not run a diesel that makes lots of torque way down low, peak power by 2.5k and revs to just 3k? Why run a big old V8 when a small, hotrodded 4cyl engine with a turbo does the job just as well and uses half the gasoline? Why run a carburetor when fuel injection keeps AFR within a much tighter range? Why run a manual transmission when an automatic is way easier on the rest of the drivetrain and faster too?

Why run an internal combustion engine when electric cars are so damn quick?

We do it because life is short and gas engines are FUN. :D
The sound and the feeling of revving a good breathing motor out is an absolute blast. A motor that is built to handle the revs and actually make power up there is a rare and fantastic experience.
 
The 340 in my '70 dart has seen 6500 rpm shifts regularly in the 19 years ive had it back on the road. I dont push it to 7000 because of the hydraulic lifters and stock valvetrain - there is no point.
 
This 470 stroker has seen hundreds of 8000 rpm shifts with nos. Even my old 340s with solid cams reved to 7000, well that’s what the tac said. Kim

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B blocks have an inherently stronger bottom end than the RB engines. Mains are better supported. A 383 stroke is only 1/16" greater than a 340. Kind of a larger small block.

Modern SS/AH Gen2 Hemis zing to, or just under, 10,000.
But they're tuned and maintained better than a chocolate-covered beer mug.
 
Oldmanmopar said:
I have always taken stock 340 up past 6000. Some stayed together for a long time . Some couldn't take it once. Everyone I put a hole in was a 4spd car shifting third with steel mounts. Always number 7 or 6 right behind the mounts? I think the strongest that i have owned at high RPM's were the 383's Them dam motors took a beating. I had many RR's and Bee's. After a couple drinks back in the 70's I would try and blow them up. Hold some flat to the floor with the clutch in for a couple seconds and then let the clutch fly and pull second as soon as the car would leap.

The GTX's and R/T's 440's couldn't take that. I would put the Dana and the 18 spline in the 383 cars add a solid lift cam and you would have a indestructible carnival ride .

Yeah I was stripping B's back then I was hard on them and used the parts myself. Back when street racing was fun when they didn't have radials. If you didn't have slicks on you didn't stand a chance making money. Steel rims with Cheater slicks was the sly move.
Click to expand...
Ditto on 383 being the toughest by far.
 
My old 69 Dart 383 4spd race car that I ran in super stock. Side stepped the clutch at 6k, shifted at 7700, and went through the traps at a little over 8k.
 
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