420A Bottom End

[Lightning_0809]

Whats the advantage or dis advantage of running the 420A long rod kit or the standard rod kit. The motor will be turbo'd t3/t4 turbonetics hybrid turbo, megasquirt(standalone) cams most all the good stuff. Its a street car no rally racing or anything. Thanks and sorry if this has been asked a million times I did search.

 

[LD25Delta9]

The long rod kit will up your compression ratio, which will give you better low end and throttle response. On the other hand, with a higher compression ratio there is more chance for detonation under high boost.

 

[Lightning_0809]

how would it up the compression ratio with th 8.6 to 1 cr pistons. also would it affect the rpms make it rev faster higher?

 

[GsXdSmKingGsX]

Your compression will go down allowing you to run more boost but watch your logger for knock, because it will increase

 

[CODE4]

Your rod length will not affect your compression ratio WHATSOEVER if you are using the appropriately mated pistons for the long rod kit. Do not listen to these replies.

An good article describing long rod effects: http://www.stahlheaders.com/Lit_Rod Length.htm

The rod length has an effect on speed at BDC and TDC.

 

[black cotton]

Code4 is correct long rod has absolutely no correlation to compression ratio what so ever.

outside of reading the article a quick fact on long rongs...

Long rods: due to the increased length in rod shaft length, the rotational radius thus becomes longer. Because of this increased attribute the piston itself is given longer time (note we're talking milli seconds) to stand at both Top Dead Center, and Bottom Dead Center. The benifits to having this increased attribute, is to A: Increased TDC Piston Dwel time, enables the air fuel mixture a longer period of time to burn thus resulting in a longer more complete burn, this in turn will help generate more power. On the flip side B: longer BDC piston dwel time, enables for longer air intake time, thus in a booster motor, giving the turbo more time to cram more air into the cylinder. And as we all know, more air + more fuel = more power.

Thats the skinny of it in a nut shell. If you are building a basic bottom end, and just looking for a slight edge, their is no reason NOT to make the motor a long rod, being parts are the same cost.

 

[all_motor_mike]

everytime the long rod question come up i just say something like "the pistons have more dwell some u make more tq/power" but what cotton wrote is everything u need to know. another thing that was not mentioned is that longer rods make for a better rod stroke ratio, the 2l is at 1.67 r/s ratio i think and by doing the .136 longer rods brings u to 1.71 (i think...... i havent done the math in a few years) and that makes for less side loading on the cylinder walls which will in theory make for longer engine life.


mike

 

[Lightning_0809]

Anyone know where u can get the long rod kit from. I know you can get it howell but there was also another site and i cant seen to find it. thanks for your help guys.

 

[all_motor_mike]

Anyone know where u can get the long rod kit from. I know you can get it howell but there was also another site and i cant seen to find it. thanks for your help guys.

i just happen to have a new long rod set that ive never used........... in case u cant find any i sell u mine.



mike