Muddytazz
1 ton status
A small block 400 comes stock with 5.565"rods. I'm going to be rebuilding my 400 here shortly and am trying to figure out what/why the benefit of upgrading to 5.7" or 6" rods? Is there really any added benefit to doing this?
CK5
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SB400 rods
- Thread starter Muddytazz
- Start date
84_Chevy_K10
Banned
Forget the 6" rods, they're not practical for a street engine in my opinion.
The reason to go with the 5.7" rods is rod angle. It reduces the side loading on the pistons (reducing bore wear) and also prolongs the time the piston stays at TDC and BDC. It is theorized that this will result in more power, although not really proven to be significant.
If I was intending on building a street 400 that I wanted to last a long time, I'd use the 5.7 rods. If I wanted a budget motor that I was going to use on the trail, I'd likely use the 5.565" rods. If I was buying pistons already I'd definitely go 5.7".
The reason to go with the 5.7" rods is rod angle. It reduces the side loading on the pistons (reducing bore wear) and also prolongs the time the piston stays at TDC and BDC. It is theorized that this will result in more power, although not really proven to be significant.
If I was intending on building a street 400 that I wanted to last a long time, I'd use the 5.7 rods. If I wanted a budget motor that I was going to use on the trail, I'd likely use the 5.565" rods. If I was buying pistons already I'd definitely go 5.7".
84_Chevy_K10 said:
What he said. The 5.7" rod is better in every aspect (except you have to scavenge some rods from a 350). Better power, longer lasting engine, etc.
SUBFAN
1/2 ton status
5.7's for sure, the 6" is possible....http://www.chevyhiperformance.com/techarticles/148_0401_imp/
Good reading....
Good reading....
Beast388
1/2 ton status
I'll hop on the bandwagon and recommend the 5.7 rods too, but only if you are buying pistons. If not, the 5.565's will work just fine.
I'd stay away from the 6.0" on a street motor due to the fact that the compression height (wrist pin location) leaves the oil-control rings somewhat unsupported.
400 piston with 6.0" rod:
400 piston with 5.7" rod:
I just like the support under that oil-ring. I'd rather have a bit more durablity and peace of mind in a street/DD motor.
I'd stay away from the 6.0" on a street motor due to the fact that the compression height (wrist pin location) leaves the oil-control rings somewhat unsupported.
400 piston with 6.0" rod:
400 piston with 5.7" rod:
I just like the support under that oil-ring. I'd rather have a bit more durablity and peace of mind in a street/DD motor.
I've got 5.565" rods in my 406 and no problems.
rjfguitar said:
Of course you have no problem. We are just saying that it is such an easy mod that it is worth the roughly 1% gain in power (I saw a very complex program that compared the three SBC rods and what power they would make) and the better engine wear.
