9,000rpm oem rotating assembly, how would you do it?
Mar 22, 2012 | 10:10 PM
#52
I have been working on this for a little while now , when I mentioned it everyone said no low end torque build a stroker blah, blah ,blah mine started life with an 07 4.8 and a 08 ly6 . i have gone through about 2 sets of 4.8 rods to find a full set all close in wieght now I'm going to ARP bolt em and hone them then smooth and balance I'm using the ly6 pistons (just bought another set in case they get f ed up taking em off the rods ) the heads are coming apart for lightwieght valves ( thinking ls3 valves) or ls9? its going in my swhen blazer 2wd gutted with a t56 and 8.5 rear and promise i wont shift till it stops pulling or gets quiet 
Mar 23, 2012 | 11:34 AM
#54
I have been working on this for a little while now , when I mentioned it everyone said no low end torque build a stroker blah, blah ,blah mine started life with an 07 4.8 and a 08 ly6 . i have gone through about 2 sets of 4.8 rods to find a full set all close in wieght now I'm going to ARP bolt em and hone them then smooth and balance I'm using the ly6 pistons (just bought another set in case they get f ed up taking em off the rods ) the heads are coming apart for lightwieght valves ( thinking ls3 valves) or ls9? its going in my swhen blazer 2wd gutted with a t56 and 8.5 rear and promise i wont shift till it stops pulling or gets quiet
Mar 23, 2012 | 11:50 AM
#55
Some things i would consider are staking the mains, removing all the casting flash from the crank, knife edge itand try to polish the entire thing. You want the counter weights as smooth as possible so the oil will just slide off of it. I would also try to cut it down an much as possible to keep it super light. Clean the casting off of the rods as well would be a huge improvement. Id try to find as many rods as possible and pick the lightest out of the bunch to start with. Same with pistons too. They already have a short skirt from the factory compared to the gen 1's.
as far as valve train goes ive spun my old 402 to 8500 with stock rockers, comp lifters, magnum pushrods and pac springs. I'd really focus on making sure your spring hights and everything is in check.
Your gonna need a good head cam intake to go that high. With that sma of cubes i dont see why a set of cnc'd l92's wouldnt work.
as far as valve train goes ive spun my old 402 to 8500 with stock rockers, comp lifters, magnum pushrods and pac springs. I'd really focus on making sure your spring hights and everything is in check.
Your gonna need a good head cam intake to go that high. With that sma of cubes i dont see why a set of cnc'd l92's wouldnt work.
Mar 23, 2012 | 04:28 PM
#59
Idea
No offense whplsh but, I don't think all this stuff is necessary.When you knife edge a crank, isn't that going to take away a lot of material? In a internally balanced motor with a stock rod, I would think you wouldn't be able to balance that motor..... Just a balance as stated before and good bolts and bearings I believe is all you need. knife edging, polishing the whole crank and finding the lightest rods to match seems a little far fetched to me. The rods aren't going to weigh that much different. Plus they are matched at the time of the balancing of the rotating assy..... they will make sure all weigh the same.
I've been seriously thinking about doing a build like this for my GTO. My thought was using a LS6 block or a Aluminum 5.3 block bored to 3.898-3.905 to accept a set of Forged slugs designed for a 4" stroke and 6.125" rods. Then, since using a 3.26" crank, get a company to custom manufacture a set of Lightweight hybrid I/H beam rods for those specs. It'd end up being roughly a 6.492" rod, even longer than the stock 4.8" rods. Have those designed with the piston skirt dimensions in mind so that you don't end up with any conflicts there. Hell, there might even be an off the shelf rod that could be machined a little bit to make it work with the off the shelf forged stroker pistons.
You might also want to take a look at A.I.'s 218cc 706/862 heads, or their 219cc 241 heads to help keep compression up where you're wanting it.
Last edited by ForcedTQ; Mar 23, 2012 at 04:53 PM.
Mar 23, 2012 | 07:09 PM
#60
Staging Lane
Joined: Feb 2012
Posts: 56
Likes: 0
From: Anchorage, AK
rotating weight
No offense whplsh but, I don't think all this stuff is necessary.When you knife edge a crank, isn't that going to take away a lot of material? In a internally balanced motor with a stock rod, I would think you wouldn't be able to balance that motor..... Just a balance as stated before and good bolts and bearings I believe is all you need. knife edging, polishing the whole crank and finding the lightest rods to match seems a little far fetched to me. The rods aren't going to weigh that much different. Plus they are matched at the time of the balancing of the rotating assy..... they will make sure all weigh the same.
I used to work in a machine shop and we had a chart on the wall which showed weight's vs rpm and how much mass is generated.
When balancing you find the lightest rod and make them all that weight.
Knife edge cranks cut down on windage, which creates less crankcase psi and oil flying around. IE slowing down the rotating assem
Internally balanced engines can use all the above mentioned mods. IMHO