4.6L crank etc in 3.9L block

[Evan]

Hi all,

Can a 4.6L crank and rods etc be put in a 97/98 model 3.9L engine ?
whats with the cross bolted stuff in the 4.6 , wouldn't the 3.9l engine also be a cross bolted design ?

Evan

[Bush65]

I haven't had anything to do with 3.9's. The 4.6 has larger journals. The heads of the cross bolts are clearly visible on the outside of the crankcase, so it should be easy to tell if the 3.9 has them.

[mickrangie]

Hi all,

Can a 4.6L crank and rods etc be put in a 97/98 model 3.9L engine ?
whats with the cross bolted stuff in the 4.6 , wouldn't the 3.9l engine also be a cross bolted design ?

Evan

I was toying with the idea of puttin a crank out of one of the 4.6 motors i have but with only 5000k on my 3.9 and having recently dynoed i really couldn't be bothered taking the motor out again..... and more to the point my GF would have my nuts cause I have a house to renovate.....


The 4.6 crank has bigger journals and the 4 bolt main and uses a different CAM.. There are no other phsical differences at all. LR use the same rings, pistons in the 3.9 as the 4.6 the only other thing I havn't checked and maybe some on the forum could help out with is, does the 4.6 use bigger rods? but that wouldn't matter if you have the 4.6 rods in the 3.9 block


HTH

Mick

BTW all the motors are gone!!!

Will try and source some more in the next few months...

[Evan]

What have you done to your 3.9 ? and how did it dyno , did you do a power run or just tuning ?
I need to rebuild my 3.9 or replace it, or go a 4.6 or i dont know yet. Superchargeing is expensive , rebuilding motor to 4.9l almost seems cheaper.
Evan

[mickrangie]

What have you done to your 3.9 ? and how did it dyno , did you do a power run or just tuning ?
I need to rebuild my 3.9 or replace it, or go a 4.6 or i dont know yet. Superchargeing is expensive , rebuilding motor to 4.9l almost seems cheaper.
Evan

I got rid of the Lucas ECU and replaced it with a Wolf 3d computer..

It's no 4.6 but it's a lot beter on the juice and power... I am very happy with the way it go's now..
put it this way It drive's like it did when it was std with 29" tyres and no chunks of steel attached..... I run 4.11 diffs and 33" road slicks round town and 35" ET's for the bush.... It moves a lot better with the ET's then the 33" (gearing is to low with 33") so some 35 or 36" road's might be on the cards soon.

[Evan]

Sweet, i was going to use autronic becuase i can get SMC's at a good price. I can only dream of tyres that big because mine is a disco but hey its also the tow car sometimes so cant have huge treads.
Does all i ask of it i guess.

For ages i have been pondering if to keep it (cheapest), buy a late 80's early 90's rangie, or get a company leased car D90 new disco or soemthing else. tooo many decisions !

Evan

[mickrangie]

hmmm get a D90 with 38"........


here is a pic of my Dyno chart...

Andrew from LRA was telling me they did a 4.6 + supercharger conversion the other week and got a 187kw at the rear wheels!!!!!!!! I got 79kw so the 4.6 with SC would be horn!!!