4lt V8 and 4.6lt V8 differance

[CraigH]

Hi guys,
I'm going to look at a D2a on Friday and the guy who is selling it claims it has has a 4.6lt short engine fitted to it not long after he purchased it 5years ago. I asked him why, did it slip a cylinder liner or over heat and what did it cost? He said he wanted more power and it cost him around $5-6k.

He said he has the receipt for the engine fitted.

Apart from driving it to feel the performance difference, is there a way of visual inspection you can tell the difference between the 4.0lt V8 and the 4.6lt V8?

Cheers
Craig

[brougham]

When I tested v8s I found a definite difference in driving the 4.6 fitted cars. They just seemed snappier at city driving, less hesitation and not worried by the car's weight.

[walker]

You should be able to get the engine number from the block which should tell you if it's a 4.6

[clubagreenie]

4.0 will probably be 42 or 44a, 4.6 46 or 48a.

There will be a definite difference but ask what he's done, if anything, about ECU.

[brougham]

Sorry missed the 'visual' bit.

[walker]

4.0 will probably be 42 or 44a, 4.6 46 or 48a.

There will be a definite difference but ask what he's done, if anything, about ECU.

The 4.6 in my Rangie ute is 59, I havnt checked what the Disco is.

[clubagreenie]

Where did you source it?

46, 60 & 96 are the choice, high comp.

[walker]

I bought the block from Deacon Automotive. It wasn't high comp but I installed high comp pistons when I rebuilt it.

[walker]

Here is a good site with all the V8 engine numbers.

Rover V8 Engine Numbers (http://www.rimmerbros.co.uk/content--name-Rover-V8-Engine-Numbers)

[wopac5]

Funny thing...I have an original matching numbers and it has a 56D engine for a 4.0lt V8 Hi comp. motor...not listed????

[Collins]

Funny thing...I have an original matching numbers and it has a 56D engine for a 4.0lt V8 Hi comp. motor...not listed????

Same here, have a 55D engine number, 4.0L low compression, not listed.
Not a very comprehensive listing

[101RRS]

The stroke in the two engines is as follows 4.6 = 82mm
4.0 = 71mm

If you are able you could remove a spark plug and measure the stroke.

Garry

[101RRS]

Here is a good site with all the V8 engine numbers.

Rover V8 Engine Numbers (http://www.rimmerbros.co.uk/content--name-Rover-V8-Engine-Numbers)


Same here, have a 55D engine number, 4.0L low compression, not listed.
Not a very comprehensive listing

I have been trying to determine whether my D2 4.0 engine is Hi comp or low comp. No VIN but engine number is 55D03758A - due to the block being skimmed the comp ratio stamped on the engine number pad has been removed. I have been searching the engine number vs comp ratio lists online and finding numbers for 4.0 RRs but not D2s. As part of that search I came across this old thread that I had previously contributed too.

So on the basis of the above quotes can I definitely assume the engine I have is low comp??


Thanks

Garry

[loanrangie]

The depth of the dish in the pistons should be a give away.

Sent from my K4000_PRO using AULRO mobile app

[Pedro_The_Swift]

was there such a beast as a low comp 4L thor??
the dish on the 4.6 is bigger, but compression due to the stroke remains the same as the 4L
none of the 3.9 engine parts transfer,
apparently you can buy low comp pistons,, (which I would guess would be the 4.6 ones)
and transferring the 4l pistons to the 4.6 will give you higher comp

[101RRS]

The depth of the dish in the pistons should be a give away.

Sent from my K4000_PRO using AULRO mobile app

Yes but hard to measure when the engine is still assembled.


was there such a beast as a low comp 4L thor??
the dish on the 4.6 is bigger, but compression due to the stroke remains the same as the 4L
none of the 3.9 engine parts transfer,
apparently you can buy low comp pistons,, (which I would guess would be the 4.6 ones)
and transferring the 4l pistons to the 4.6 will give you higher comp

Thanks - understand all that but Collins above indicated his 4.0 was Low comp and his engine number starts with 55D so just seeking confirmation.

Cheers

garry

[discorevy]

do a compression test , this will tell you the ratio and the state of the engine

[Pedro_The_Swift]

55D = South Africa. ?

[101RRS]

do a compression test , this will tell you the ratio and the state of the engine

Thanks - but I asked the question relevant to the engine number for a particular reason, mainly that the engine is assembled but not in the vehicle so not running. Not wanting to proceed until I resolve this.

Most RV8 engine number lists have just about every RV8 listed but not 4.0V8s in D2s.

Cheers

Garry

[discorevy]

Easy enough to do comp test with engine out of car , just need a flywheel and starter bolted up

[ballbag]

I have 1999 4L low comp engine number 55D.