Double check that 1958 year engine list.
A 383 RB engine was available.
bore vs stroke
- Thread starter Wyrmrider
- Start date
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A 383 RB engine was available.
That's why it would be interesting to build identical 340 and 360 to compare...
yellow rose
Overnight Sensation
Right. So by YOUR definition, the 360 would be UNDER your ratio and the 340 will be right at it.
And if we did your little test (which happens to happen every single weekend at drag strips around the country) you'd soon find the 340, even at the same weight will beat the 360. You can use more gear, more converter and more RPM. That beats your torque every day of the week and twice on Sunday.
Go look at Comp Eliminator. Better yet, research Modifed Eliminator. You'll get the picture.
Biggest bore you can get, shortest stroke to get displacement, the longest Rod you can stuff in there and get the chassis and drivetrain tuned up.
Simple really.
MOPAROFFICIAL
Oogliboogli
a bigger difference would be more adhesive to the point of the article
.100 bore diff, .50 stroke diff.
.100 bore diff, .50 stroke diff.
Wyrmrider
Well-Known Member
sorry krazy
there was a RB 383 4 1/32 bore nominal 4.030
59 & 60 around 100 000 made
otherwise great contributions
there was a RB 383 4 1/32 bore nominal 4.030
59 & 60 around 100 000 made
otherwise great contributions
Ohhhhh!!!! There’s the magic!!!!
But I think we were just talking about dyno runs for fun.
But I think we were just talking about dyno runs for fun.
I feel both would have very similar power bands. The small bore big stroke would on paper would be a little more efficient in a fuel economy pollution kind of way, why a lot of newer engine are built that way.
Surface area of the piston affects the burning, once the burning is done, it's the cylinder pressure that pushes down on the piston... The mixture does not burn for the whole stroke, but just until all of the gasses are burned and the efficiency of the burning... Once the gasses are burned, the pressure in the cylinder is what pushes the piston down...
Now when the piston is at mid stroke, the crank is at 90° which is the pure definition of torque - force times perpendicular distance... The longer the stroke, the more perpendicular distance, hence the greater torque generated...
Also at mid stroke is maximum side load on the piston as the force is maximum when the crank is at 90°... That's why most cylinder wear is measured at mid stroke in the bore... A longer stroke with the same rod length will increase side load on the piston and cylinder wear...
The more gear, more converter are more variables to the equation...
Just run the numbers of identical 340 vs 360 on a dyno to see how they affect the output...
I don't know much about the 50's engines... What was the stroke and bore on the 50's 383???
IIRC, 4.03 X 3.75.... Hold on a second... BRB...
There—-> Mopar (Chrysler, Dodge, Plymouth) RB series V8 engines: 383, 413, 440, and 426
Thanks, I've never looked that far back... All of my Mopars have been mid 60's to mid 70's...
yellow rose
Overnight Sensation
Who cares? We already know that the induction/exhaust systems define power. The other parameters define the RPM range.
Any time, ANY TIME you can get more power cycles you make more power. If you want to argue that, get a seance going and get Smokey Yunik on the horn. Or, just read his book.
It's simple science. It's all about TIME. How much WORK (power) can you do in a set amount of time (1320 feet as an example).
You have 1320 feet to get as many firing cycles in as you can get. In a circle track race, it's how many power cycles you can get from corner to corner.
It's simple physics and math.
Now, I won't argue if you think that blowing the tires off the car at highway speeds is cool, if you think every time you try and drag race you can't get any "hook" and you ***** because the track prep is crap, except right after you couldn't hook your stroker a AA/GS legal car goes up and runs 200 plus MPH in the 6.80's, then you can have that.
The more traction limited you are, the more stroke length kills you. Made many circle track cars (especially on dirt) go quicker with shorter stroke bigger bore combos.
I'm not in the group who thinks smoking the tires is cool.
MOPAROFFICIAL
Oogliboogli
Lol Right on.
yellow rose
Overnight Sensation
I think for most guys the decision on what your engine geometry should be, should be based on how much RPM, gear, converter are you comfortable with.
If you think 6000 is zinging it up there and you love 3.23 gears, then by all means, put some arm in it.
If you don't mind shifting at 7000ish and you can live with the gearing it takes to do it, the take some 4.10's and throw a 4K converter at it and let it eat.
If you have rocks in your head, and you think 8500 is cool then the biggest bore you can get, a reasonable stroke length (for that RPM 3.79 would be about IT for me) the longest Rod you can stuff in there and get a reasonable ring belt and gear and converter it for it and let 'er rip. But you better have your crap wired tight. The tune up window is almost nonexistent and even a small error is catastrophic...BTDT.
I think for most guys on here, RPM should dictate what you do.
If you think 6000 is zinging it up there and you love 3.23 gears, then by all means, put some arm in it.
If you don't mind shifting at 7000ish and you can live with the gearing it takes to do it, the take some 4.10's and throw a 4K converter at it and let it eat.
If you have rocks in your head, and you think 8500 is cool then the biggest bore you can get, a reasonable stroke length (for that RPM 3.79 would be about IT for me) the longest Rod you can stuff in there and get a reasonable ring belt and gear and converter it for it and let 'er rip. But you better have your crap wired tight. The tune up window is almost nonexistent and even a small error is catastrophic...BTDT.
I think for most guys on here, RPM should dictate what you do.
They actually don’t even touch their engines. Kim
Back in the early 80 a buddy was running 340s at 10.70. He then built a 360 after blowing up the 340. Both had the Mopar performance pistons for the same compression for their size. He used the same heads, induction and roller cam from the 340. The 340 ran 2/10s faster. Kim
Generally, tractors and semi's use long stroke engines to maintain the torque as engine speed decreases. In a racing engine the torque drops dramatically as the rev's drop. If a nascar engine is tuned for 10,000 rpm, how much power does it put out at 3,000 rpm? And if you put that 800 hp nascar engine in a loaded semi that originally came with a 220 hp Cummins, you wouldn't be happy with the results.
Wyrmrider
Well-Known Member
Not so krazy
I hope you meant- when discussing wear above- that the rod and crank throw were at 90 degrees not that the crank was 90 degrees on the degree wheel
When Rod is perpendicular to the crank is when you have the most leverage, torque, and side thrust this is also when piston speed is highest
But flow lags this point but you still want to have the induction flowing good
Note that the short rod engines get to this point many (a few but it matters) crank degrees earlier than long rod engines so the chevies have to start opening the intake earlier to get the flow curve right. One reason not to use a chevy camgrinder to spec your mopar cam. You can easily end up with more overlap and reversion
Some say the factory did not have enough capacity (or would have had to add shifts) to make more 383 B motors but the RB line had capacity to spare so they cranked out the small bore 383's
Good luck finding pistons
If you look at the production figures there were many times more B than RB
I hope you meant- when discussing wear above- that the rod and crank throw were at 90 degrees not that the crank was 90 degrees on the degree wheel
When Rod is perpendicular to the crank is when you have the most leverage, torque, and side thrust this is also when piston speed is highest
But flow lags this point but you still want to have the induction flowing good
Note that the short rod engines get to this point many (a few but it matters) crank degrees earlier than long rod engines so the chevies have to start opening the intake earlier to get the flow curve right. One reason not to use a chevy camgrinder to spec your mopar cam. You can easily end up with more overlap and reversion
Some say the factory did not have enough capacity (or would have had to add shifts) to make more 383 B motors but the RB line had capacity to spare so they cranked out the small bore 383's
Good luck finding pistons
If you look at the production figures there were many times more B than RB
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