My 4.6 V8 Rebuild Thread

[101RRS]

The D2 already has a very low max torque rpm,,
going to a 4.6 with the standard cam should give you, what 20% (?) more at the same revs,, 9.1 should bump the other up too,,
how many revs at 100kph Gary?

Somewhere around 3200rpm. You are right about the increase in torque just by going to a 4.6. Low down the 3.5 has more than enough with the 101 low gearing so I am not too worried about the lower end but mid range need to be better - again a standard 4.6 will provide this but more will be better. I am not after higher speed as on the flat the 3.5 will pull it faster than the chassis really wants to go but it just has to see a gentle hill and it dies in fourth and to a lesser extent third - slow down enough to get into second then it just pulls like a train.

So an increase in mid range torque is what I want.

An aftermarket cam might just be a bit harder and last a bit longer to.

After Phillip's thread a while back about his issues with a new cam I also had this in the back of my mind. Though the 4.0 cam (I think the same as a standard 4.6) I have has just been run in and is in great condition.

Cheers

Garry

[clubagreenie]

When I pulled my 4.0 it was fairly shagged out and the cam (I know it was at least it's second by receipts in 180,000k's) was equally shagged. Some lobes were no higher than the bearing surfaces.

[101RRS]

The 4.0 engine I have had only done 40,000km and was only scrapped because of an over torqued head bolt stripping the block thread. I probably could have simply reassembled the engine after the block repair but I want to make sure there are no other issues.

Cheers

garry

[ozscott]

I have just had a Crow tow (their mid level) cam installed. I will let you know how it goes but the mechanic reckons it goes harder than a stock One (its got some head work too) and torque is up can short shift with no probs and she pulls... Eg first to third.

Cheers

[ozscott]

When I pulled my 4.0 it was fairly shagged out and the cam (I know it was at least it's second by receipts in 180,000k's) was equally shagged. Some lobes were no higher than the bearing surfaces.

My cam at 200 000 was sweet but I wanted extra grunt. Mobil 1 for most of warranty then from 100k Penrite hpr 10.

Cheers

[101RRS]

I have just had a Crow tow (their mid level) cam installed. I will let you know how it goes but the mechanic reckons it goes harder than a stock One (its got some head work too) and torque is up can short shift with no probs and she pulls... Eg first to third.

Cheers

Thanks - what head work did you get done. The engine builder indicated that he thought the valves in the Rover V8 were a little small for a 4.6 so when I get to the heads I will need to have a look at what mods I need.

Garry

[ozscott]

Basics only mate - chemical clean, new inserts, ported exhaust and intake ports to match the gaskets.

Cheers

[clubagreenie]

It's a big job (in the scope of things you are planning) to machine out to replace with bigger valves. I'd be looking at some options of off the shelf stuff available.

Sorry, re your other question about Mark Adams, he's on here as user, Mark Adams. Can't exactly remember his website but I think it's Tornado Systems or something similar. He chips D2's and has a lot of knowledge in the tuning dept.

[101RRS]

I am not really up on things like valves etc so I will look into it a bit closer when I get to it. The heads I have really do not need any work other than cleaning up and maybe port matching - if work is difficult for little gain I will not get it done but if easy then I may do.

I will look up Mark on here.

Thanks

Garry

[clubagreenie]

Yeah lots of work vs gain and it really needs to be part of a bigger upgrade path if induction. Such as inlet, larger MAF (or elimination), cams, valves, exhaust.

The V8's they ran in the grp A 3500's had little if any actual valve work. I know they are smaller but as a comparison the Toyota 1UZ (4.0) runs same set up in that, the 4.7 and larger. I went to the maximum lift and duration that could be done within the scope of machining the original heads for lobe clearance and spring capacity (added about 6-7mm to the tip of the lobe in weld) and still used the stock valves and they weren't the restrictive area of the intake.