upgrade 4.0 to 4.6

barginbucket · Post by **barginbucket** » Thu May 17, 2007 9:09 pm

just a quick one,what parts do i require to upgrade my 4.0 [crossbolted] to 4.6,just a 4.6 crank and rods maybe or pistons as well,cheers

ihatesissycars · Post by **ihatesissycars** » Thu May 17, 2007 9:17 pm

Crank and rods. If you reuse the 4.0 pistons you get a hike in compression, about 10.5:1 i fink. A rebalance might be a good idea though.

Post by **katanaman** » Thu May 17, 2007 9:19 pm

crank and rods, keep your 4.0 pistons if you want higher compression ratio.

barginbucket · Post by **barginbucket** » Thu May 17, 2007 9:55 pm

thanks good people,top site with top people,will be keeping a beadie eye out for those parts then

jrv8 · Post by **jrv8** » Thu May 17, 2007 11:20 pm

Hi ,
I have a 4.6 crank for sale , if you're interested in it.
It's been ground 10 thou all over , and comes complete with new main and big end bearings.
Jim

mgbloke · Post by **mgbloke** » Fri May 18, 2007 6:57 am

Ive done this to my enging. Yes its just crank and rods.Its well worth keeping the 4.0L pistons as they have a smaller dish to help raise CR.
Once you have driven the 4.6 the 4.0L will seem weedy in comparison.
Have you modified the heads? as this will help too.

Mark

adamnreeves · Post by **adamnreeves** » Fri May 18, 2007 3:17 pm

I think you will need to check the clearance with the sump and at the bottom of the cylinders with a 4.6 crank has it has large lobes. Note sure but well worth checking!

barginbucket · Post by **barginbucket** » Fri May 18, 2007 7:56 pm

thanks fella's,yes heads are modified 41.5/35.5[a bit tame compared to today standards],webber 500,mallery unilite,real steel stomp puller cam,[you cant beat torque on the real roads],is there any disadvatages for raising the comp/ratio i should look for,and sorry can i use my existing bearing caps with 4.6 crank

i need a new clutch so i might upgrade her when shes out

thanks again

steve

Post by **katanaman** » Fri May 18, 2007 8:07 pm

Yes you can use your bearing caps, a 4.0 and 4.6 block is the same thing with different serial numbers on them. Its been said that they are graded differently with the highest quality blocks being the 4.6. I dont know if its true or not or even if its anything to bother about.

More compression is always better (unless your forced induction) but with that cam I wouldnt go any further than using the 4.0 pistons unless you want to run the risk of running into detonation on standard unleaded fuel.

barginbucket · Post by **barginbucket** » Sat May 19, 2007 4:41 pm

cheers for the advice marki