P38A Difference between 4.0 and 4.6 Thor

domino · Jul 27, 2016

Would I be right in saying the only difference between these cars (in the engine bay) is the internals of the engine i.e. the stroke. Everything else is the same such as alternator, ac system, radiator etc?

tomcat59alan · Jul 27, 2016

domino said:
Would I be right in saying the only difference between these cars (in the engine bay) is the internals of the engine i.e. the stroke. Everything else is the same such as alternator, ac system, radiator etc?

Inlet system is different for a start.

Saint.V8 · Jul 27, 2016

tomcat59alan said:
Inlet system is different for a start.

Both the 4.0 and 4.6 THOR engines are the same in that respect Alan.....GEMS and THOR are different which is probably what your were thinking of.

The only differences between the 4.0 and 4.6 in both GEMS and THOR variants is the Crankshaft and Camshaft....to acheive 4.6 they stroked the crank....bore size is the same.

domino · Jul 27, 2016

Excellent. Thanks Ant, just as I thought.

tomcat59alan · Jul 27, 2016

Saint.V8 said:
Both the 4.0 and 4.6 THOR engines are the same in that respect Alan.....GEMS and THOR are different which is probably what your were thinking of.

The only differences between the 4.0 and 4.6 in both GEMS and THOR variants is the Crankshaft and Camshaft....to acheive 4.6 they stroked the crank....bore size is the same.

I stand corrected.

Misread it as Thor and Gems.

martynv8 · Jul 28, 2016

As Ant said,
The crankshaft, con rods, pistons & cam are the only changes. I have the 4.0L pistons fitted to 4.6 crank & con rods to up the compression on my 4.6 (there is less dish on the 4.0 piston crowns).

gazman · Jul 28, 2016

it's obvious the differences. it's 0.6 obviously

martynv8 · Jul 28, 2016

PS. The 4.6 has the stronger ZFHP24 transmission. I assume the engine ECU is different. Maybe it can be re-programmed for 4.6?
Assuming you are looking at transplanting a 4.6 into your 4.0?

rewmer · Jul 28, 2016

isnt the 4.6 cross bolted ?

pwood999 · Jul 28, 2016

so is the 4.0

martynv8 · Jul 29, 2016

rewmer said:
isnt the 4.6 cross bolted ?

Think all Rover V8 blocks are cross bolted above 3.5.....stronger for the crank....weaker for the liners

domino · Jul 29, 2016

martynv8 said:
PS. The 4.6 has the stronger ZFHP24 transmission. I assume the engine ECU is different. Maybe it can be re-programmed for 4.6?
Assuming you are looking at transplanting a 4.6 into your 4.0?

Nope - just when replacing bits like radiator, air-con etc, I can get stuff from a 4.6 Thor.

Does raise the question of there are any interchangeable parts from the gems to Thor similar to the above?

biketeacherdave · Jul 29, 2016

The most obvious difference........ Its faster..

tomcat59alan · Jul 30, 2016

biketeacherdave said:
The most obvious difference........ Its faster..

Only from a "teacher".

jamesmartin · Jul 30, 2016

martynv8 said:
Think all Rover V8 blocks are cross bolted above 3.5.....stronger for the crank....weaker for the liners

most of the 3.9s wernt, im not sure why its worse for the liners, they are below liner level

martynv8 · Jul 30, 2016

jamesmartin said:
most of the 3.9s wernt, im not sure why its worse for the liners, they are below liner level

I meant the cross bolting on 3.9 & 4.6 made for a stronger crank but boring out to 94mm created it's own problems....liners!

jamesmartin · Jul 30, 2016

martynv8 said:
I meant the cross bolting on 3.9 & 4.6 made for a stronger crank but boring out to 94mm created it's own problems....liners!

my bad ,too right it did

fanatic · Jul 30, 2016

Burn it

P38A Difference between 4.0 and 4.6 Thor

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