Mopar 383 vs Chevy 383 stroker

[BLK 68 R/T]

Found this video over on Moparts. Pretty cool!

https://www.youtube.com/watch?v=L-uV61qilqU

Edit: here is the Moparts link
http://board.moparts.org/ubbthreads/ubbthreads.php/topics/1978263/engine-masters-dyno-shootout-mopar-383-vs-chevy-383.html#Post1978263

[skip68]

Awesome low end mopar power.   Thanks for posting.   
I've often wondered about the two.   

[BLK 68 R/T]

My guess is with a little tuning the "lowly" Mopar 383 would probably clean house on the Chevy motor 

[Ghoste]

Yes, but don't underestimate the light weight reciprocating mass and valvetrain in the Chevy and its lighter engine too.

[A383Wing]

which is why a lot of the Chrysler small blocks will out perform the B-RB engines....and why the 383 will out perform the RB engines

[Mike DC]

 
I've always been kind of mystified at why the Mopar 383 is such a torque-monster.  It seems disproportionately good for its size.    


I know the B-block advantages over the RBs.  Stiffer cylinder walls?  Bottom-end geometry?  Reciprocating weight?  bigger airflow vs displacement?  I don't see how any of that stuff explains low-compression low-RPM torque.  

I mean, 383 Magnums made well over 400 ft-lbs at 3000 RPM.  That makes sense when it's a total truck motor with small heads and a small cam.  But the 383 Magnum wasn't a truck motor.  The show wasn't over at 4500 RPM.      

[1974dodgecharger]

which is why a lot of the Chrysler small blocks will out perform the B-RB engines....and why the 383 will out perform the RB engines

NOT based on the internet gurus, lmao.......people on youtube and facebook tell me my car is NOT a 383, but a 440 because NO WAY IN HELL A 383 CAN PRODUCE THAT POWER that I have.

[c00nhunterjoe]

The 383 mopar makes good torque because of how large the bore is. Yes, i know how levers work and that a 440 has more stroke,  BUT, its the same basic principle as a see-saw. The bigger the kid is on the seat, the better the ride is going to be. The 383 chevy needs a bigger kid sitting on top of the crank to push that longer stroke down, whether it be via compression or bigger bore or both. The chryslers have big bores to start and thats why they react so well to stroker cranks.

[BLK 68 R/T]

I recall seeing a 69 383 Superbee beat a LS6 454 Chevelle in one of the pure stock drag races that was posted in muscle car review a few years back. I know driver reaction times, traction, gearing, blah blah blah all play into it but I was still impressed at the outcome.

[Mike DC]

The 383 mopar makes good torque because of how large the bore is. Yes, i know how levers work and that a 440 has more stroke,  BUT, its the same basic principle as a see-saw. The bigger the kid is on the seat, the better the ride is going to be. The 383 chevy needs a bigger kid sitting on top of the crank to push that longer stroke down, whether it be via compression or bigger bore or both. The chryslers have big bores to start and thats why they react so well to stroker cranks.

I have always doubted the "longer lever" story about big stroke motors.  When the crank throw gets longer it also means the rod angle increases and that would offset any gains.  The end result of the conventional wisdom might be true but IMO it's probably for different reasons.  Maybe piston speed & valve size. 

[A383Wing]

Ya'll should read this thread on FBBO site....some people in there are almost fighting through the computer about this

http://www.forbbodiesonly.com/moparforum/showthread.php?104198-383-chevy-versus-mopar-383

[TruckDriver]

Very cool video. And interesting. 

[Kern Dog]

Ya'll should read this thread on FBBO site....some people in there are almost fighting through the computer about this

http://www.forbbodiesonly.com/moparforum/showthread.php?104198-383-chevy-versus-mopar-383

They might end up locking that one up.

[BLK 68 R/T]

  I lost interest about the 5th time it was mentioned how much money everything cost.

[c00nhunterjoe]

Mike, longer lever will make more power. That cant be denied. But there are more factors then just putting the lo ger stroke to it. You have to have the push needed to swing that lever and in my opinion, this dyno shootout shows what i mean. The larger bore of the 383 given the grind of the cam gave a better charge then that of the smaller bore/ bigger stroke of the chevy version.

[1974dodgecharger]

Ya'll should read this thread on FBBO site....some people in there are almost fighting through the computer about this

http://www.forbbodiesonly.com/moparforum/showthread.php?104198-383-chevy-versus-mopar-383

lmao....wow!!! I guess we never grow up...I never did 

[Mike DC]

Mike, longer lever will make more power. That cant be denied. But there are more factors then just putting the lo ger stroke to it. You have to have the push needed to swing that lever and in my opinion, this dyno shootout shows what i mean. The larger bore of the 383 given the grind of the cam gave a better charge then that of the smaller bore/ bigger stroke of the chevy version.

I can agree that the bore might very well be the factor making the big torque.  Bigger bore engines are usually thought of as hi-revvers but IMO that may be more due to the room for big valves/heads.    



I can't see the lever-arm part though.  

Think about doing push-ups - does your torso get "heavier" if your arms get longer?  No.  Not if your hands are always in the same place directly under your shoulders.  Your torso weight is always pushing down directly over your hands, no matter how far your elbows do or down't kick out to the side due to arm length.  (Don't think about how you use your arm muscles here, think about how your body weight bears down against your hands.  In an engine the piston has downward force and there is no other "muscle" acting directly on the rod's pivot points.)

A piston is always pushing down directly over the crank centerline no matter how far the rod journals move out to the side.   My sense of physics says the only direct effect of strokes & rod angles would be related to piston speed & inertia.

[c00nhunterjoe]

Think of the bore discussion as the analogy of swinging a hammer with 2 different size heads but the same length handle. The one with the heavier head will clearly give you more power to drive the nail in then the smaller one. The size of the hammer head is not directly comparedto the piston size, but more of the power/pressure created in the combustion chamber as a result of it.

Compound the bore size vs stroke differences as a hammer of different length handles and different size heads.

Then move on to the physics principle of weights and levers. Center pivot points to lift a certain weight mass determines how much mass is needed on the opposing side of the pivot.

[Mike DC]

                  
I could see the stroke leverage thing maybe working in the sense of speed vs power.  The piston's force on the crank rotation is delivered more slowly with a longer stroke.  If speed is lost then force must have been gained because it's a lever.  I dunno if this effect would be very big in the practical sense though (street production engines).


And all this "stroke leverage = torque" discussion is still flying in the face of the 383 engine video's test results.  



I recall a dyno test in a magazine like 10 or 15 years ago where they tried several combinations of bore & stroke & rod ratios in a streetable SBC (always the same displacement total).  They found no real difference in how it performed.  

[crj1968]

Thats pretty good stuff- Freiberger is always pretty entertaining. As I recall he built a junkyard 318 and got some good power out of it....

$3600 for a bolt in 440HP chev motor seems a pretty good deal....you know for a Chevy guy.

Did they show the specs of that mopar 383 anywhere? 

[c00nhunterjoe]

Only thing i recall was bone stock 906s other then milling to bring the compression up to 9.5:1 and standard replaceme t .060 pistons, which tells me if they had to mill the heads to bring the compression up, they are MOST LIKELY the normal low compression slugs that we see on here frequently. The key to their hp and torque numbers is the cam profile and being a roller helped too. But as we all know, one dyno reads difference then the next, the more important thing is the comparison between the 2 engines, not the peak number