getting ready to build my blower short block, I'm on a budget so a lot of the work will be done myself. I have never built a low compression motor since I am kinda new to FI. So I have just a few questions.

This is a 94 TA NA forged pistons .30 over motor w/ a P1SC twin intercooler, 12 rib running 10lbs. Cam is a CC306. 42 lb injectors. Basicaly it is a NA motor that I threw a blower on for the summer.

1. The diffrence between using 5.7 ---> 6.0 inch rods? What does the change do and what do you give up by going with a 6.0 rod?

2. If I stroke it....how much machine work has to be done for a 3.75 stroke?

3. My block is already 0 decked and I need to bring my compression down. - 31 cc JE's sound good but, can the be run on a 6 inch rod. I have stock CC's that were milled .10 long ago.

Was scoping out Eagle crank and H-beams, just not sure about pistons and wether to stroke this motor.

Chris

 

1. 6 inch rods reduce the room available for the rings, so the ring lands get really thin and fragile.

2. Balancing a stroker costs alot more because heavy metal usually has to be added. Other than that, the block needs to be clearanced.

3. The JE's for 6" rods can be run with 6" rods. The JE's with 5.7 rods can be run with 5.7 rods.

 

Where at in Akron are you? I don't believe i've seen your car around or at any of the tracks - good luck with the combo, you'll love FI.

 

What does the change do and what do you give up by going with a 6.0 rod?

What is the effect of using a 6 inch rod, there has to be a good reason why..... I see them used but what is the advantage?


Anyone out there run a CC306 with FI? What are some guidelines foor camshaft overlap?

 

6" rods have various advantages and will make more power. Lots of information is out there on this. However, in a FI application, it weakens the piston. Most choose a shorter rod/stouter piston.

 

I'm not certain that's an issue unless you increase the rod length AND the stroke. Please correct me if I'm wrong.

However, there is another issue. A forced induction engine, whether mechanical or chemical (N2O), is on average; more prone to detonation then an NA engine. Under those circumstances it is probably better to get the piston away from the head faster, thus decreasing the time where the mixture is most prone to self-ignition. Unless of course you are running alcohol for fuel, in which case the piston dwell time might be worthwhile.

 

Basically a 6" rod will reduce side wall loading and will increase piston speed. The increased piston speed will make more horse power, but you have to be careful because you add alot more stress when you do this. Force = Mass x Acceleration Physics was good for something other than mid day naps after all.

In a nutshell, if you're using stock heads on a 383, you're going to need to stick with a 5.7" rod for compression/ringland issues. If you have access to aftermarket heads with larger chambers, then use which ever you prefer/can afford.

 

Increasing the stroke, rod length, or especially both will reduce room available for ring lands.

 

6.0 should be fine. I am running 6" on my bulit 383LT1 and have been street tuning last yrs 14psi and a few times hit 20psi no problem. I am also using JE havey duty blower/turbo piston. Any one remember BiG RICK?? his 396LT1 runing in the 8s @ 170mph. He is also running 6" rods. Just a thought.

 

The thinner ring lands are fine as long as you don't have detonation. If you do (like most at some point), then they are much less forgiving.