|07-21-2012 09:59 AM|
|CNC BLOCKS NE||WOW up from the dead!!|
|07-21-2012 09:35 AM|
350 cubic inch race engine making 400 hp?
long rods vs short rods? will it make a difference? sometimes,,, depends on rpm,combustion chamber,ie fast burn.fuel used ,piston dome shape, head material,,so basically everything.
The piston goes to the top of the bore,stops,reverses direction and stops then does it over and over.The piston accellerates from stop to, w/e,then decellerates.there fore the speeds in the bore are different rates depending on where in the bore the piston is atm. A short rod and long rod have slightly different angles just after tdc so the excelleration rates will be different for each piston. The flame propagation will be different from one head to another,fuel burn rate different,and many other factors. Many engineers coundnt form a mathematical formula for every situation.
|07-20-2012 11:34 PM|
I built the Hot Rod mag 400 block with 327 crank engine.
my variations were 10.5:1 compression , World heads with a larger runner then the 170, in the Hot Rod article.
My results were good. It was put in a 71 chevy 4X4 with 3.08 gears,and a 350 w/ shift kit. Unladen weight was 5200 lb. The engine requires 14 deg. initial advance to run decent. The cam was an rv truck cam. It ran with no problem with 82-87 octane. it would break the tires loose with little throttle position.
The pipes were twice as loud with the same headers a stock 350 engine. Man it is great having gray hair . The cops just shake thier heads when it was wound out.
|11-09-2009 06:31 AM|
|11-08-2009 06:38 AM|
|CNC BLOCKS NE||
|11-08-2009 06:21 AM|
|barnym17||Carl do you find the longer rods better in all cases or mainly in restricted induction engines?|
|11-08-2009 05:46 AM|
|11-08-2009 04:48 AM|
I had never heard of this before,and I could have got a dozen or more 300 rods for nothing a couple years ago,darn.
|11-07-2009 08:41 PM|
Not exactly what you have in mind, but that is what a 348 chev had for specs. I'm thinking the rods are 6.135"-ala the Mk IV big block. (348 is Mk I).
These were heavier, obviously, being the first big block, but they ran real nice. Real nice. Torquey.
|11-07-2009 01:35 PM|
reply to CNC blocks
I currently have 2 SBC 400's one with standard stock 5.56 rods and the other with 6.0 rods. I haven't noticed any difference. These are street engines and don't turn over 6000 rpm.
|11-07-2009 08:51 AM|
There have been many articles written both ways on long and short rods.
Nascar guys say on restricter plate engines have better performance with long rods. There power band is different than a streetcar.Some companies switch back and forth between long and short rod in the same engines and dyno them. It was my understanding from Dema Elgin that the cams should be changed when the rods are changed and I have not seen that done in anything I have read.R & M did a article in National Dragster years ago and switching rods in a Big Block chevy did little or no difference
|11-07-2009 06:17 AM|
|CNC BLOCKS NE||
We have some engines street and strip with 1.000 compression height and no problems.
The engines you have run with the long rods what have been your problems or are you one that has never tried it and are posting just hear say.
|11-06-2009 10:46 PM|
You are right, Some of the nascar engines use long rods, but get real, they run 8000-9000 RPM and run one race. In a street engine the difference is so neglible you will never notice it. Longer rods weigh more, cause short piston ring stacks and higher wrist pin placement, this is not really that good for long term reliability in a street engine. Spend money elsewhere, like cylinder heads and valve train. it will be money well spent.
|11-03-2009 11:18 AM|
|SDLuck||There is a guy running nhra with a rumor very shot rod and buzzes it really high.And is a class winner|
|11-03-2009 11:15 AM|
Cup motors are large bore short stroke long rod,but also have large port 15 degree cylinder heads
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