The V8 Owners Forum -

Thanks Minor, spoke to V8D, and was advised to check the head cc's as there are two versions apparently, then base piston choice on that. I've a set of 4.6 rods though the previous owner muddled up the caps, so instead of sorting might just bite the bullet and grab some forged internals.

I believe the chamber size of my Merlins is 31 cc.

As for forged internals, I don´t know if anyone supplies them for 4.6 engine. In any case, at least your "affordable" engine is no longer affordable

Not cheap nope


Diamond Forged Pistons & Lunati Chevy 6" H Beam Rods,

Coops wrote:Not cheap nope


Diamond Forged Pistons & Lunati Chevy 6" H Beam Rods,

Those are nice Coops what crank did you attach the to? Hopefully a forged steel one!

Ian

nope off set ground the 4.6 one mate and before you say that wont be strong enough I have been assured it will work,

a few guys (a couple on here too) have been doing it including Pel if I remember correctly and he was putting poop loads of power into his crank,

minorv8 wrote:I believe the chamber size of my Merlins is 31 cc.

As for forged internals, I don´t know if anyone supplies them for 4.6 engine. In any case, at least your "affordable" engine is no longer affordable

Mine are to.

Indeed they came in two versions, the 31cc the LC ones.
Thought the other ones had somewhere in the 20's cc but not sure as I can't find my old Real Steel catalogues which lists them.

Are these for 2,100" crank pin ? Pistons then, are these Chevy or custom pistons ?

Tony's pistons are custom, however I have been playing with the numbers for a 5.7 rod engine based on a 4.6 as we have two sets of 5.7 rods available.
This will be the rod journals turned down to 2" and offset by 0.050" in the process. With a Keith Black Ikon 305 Chevy forged piston, the stock Chevy bore size needs a 0.037 overbore on the block. With flat top pistons this will give a deck height of around 0.010 and compression will be around 12-1 to 12.5 -1. Capacity will be 289 cubic inches. I believe a dished piston is available in the Ikon range but have not looked into this as we run Methanol. I see no reason this cannot be built and the rods and pistons are available off the shelf from US mail order suppliers.

Just another option

Alan

For the ultimate rover you'll need one of these,


A billet steel work of art

the pistons came from www.v8performanceparts.co.uk I think they use an off the shelf piston with the stock 4.6 bore, along with the 6" chevy rods (2" journal)

I have a more modest option waiting for the current engine to expire:




SBC Crower 6 inch rods and Icon +20 pistons from Real Steel.

The crank is a weirdo TVR crank with around 90 mm stroke. The only issue with this crank is that it has narrow TVR sized con rod journals.



So, the rods had to be narrowed a lot, the big end width is around 19,40 mm.



The only thing missing is a good block

Blown v8 wrote:For the ultimate rover you'll need one of these,


A billet steel work of art

That looks like the Holy Grail.

What capacity will that make?

Ian

Quite some options going on.. What spec do you currently run Minor? And what's the plans? Not that keen on offsetting cranks narrowing rods etc, etc, all a bit over my head really. Doesn't look like there is a straight forward forged rod swap option? I wouldn't mind going for the 4.8 option, with forged Pistons, I understand the stroke is the same as standard with the bore taken out to 96mm. Just trying to future proof the engine a little, in case the rotrex option becomes a reality.

I spoke to Ray at V8D he suggested the +20 Pistons, are they forged Minor? He was extremely helpful without being pushy at all, will be using V8D for machining and a few induction parts.

Shopping list at V8D currently is:

Top hat block
New cam bearings, core plugs etc.
Ported inlet
Ported plenum base

Hoping to get the block to V8D between xmas and the new year.

Spoke to Tim at ACT, again an extremely helpful guy, no hard sell, in fact the opposite, mentioning that a few of the systems would be overkill for my needs. So definitely an ACT induction system is on the list. The triple system with a Morgan inlet for packaging is favourite for the bling factor, though the single Westfield type setup with a big body is the practical option.

Picking up the heads next weekend so will check the chamber size then and go from there. Probably the 31cc versions. as they've been on a TVR which I would imagine has high compression pistons.

My spec can be defined as leftovers, to be honest. A s/h block bought with one damaged cylinder (molten piston), s/h HC pistons, std crank and rods, Real Steel Tornado cam, ported Merlin heads with CNC machined seats, modified Efi intake, modified plenum with a single 75 mm throttle body (facing front). Basically nothing exotic.

My Icons are forged and have Chevy piston pin size. Thus not a direct fit to 4.6 rod. You need to keep that in mind.

Today it is hard to find a machine shop that will do offset grinding. It is slow work and if charged by hour, also pretty expensive. I think that factory crank and rods are good enough for road use, even the piston are quite modern compared to former Rover designs. Basically for road going engine I would choose a factory 4.6 bottom end. Given the engine size, it will have the best torque potential.

About the Merlins: they are an upgrade from factory heads but honestly could be a lot better. The head guy who did the CNC seat work laughed that it is unique to see heads with 4 different ports. Same performance can be made with Stage x Rover heads. And current price at RPI is ridiculous... They really are not worth that much money.

If you go the 4.8 route with 96mm bore don't forget to factor in full engine balance.

When I had my 4.6 top hat linered they (chesman's) asked - what bore do you want sir... It took a lot to say keep it standard to match my current pistons but going bigger would have cost more than 1K extra.

The standard 4.6 bottom end is strong and does handle reasonable boost very well, so long as you have it tuned well and avoid detonation.

You need to think what your long term goals are/ power levels and then hope that your budget can cope?

Bang for buck you can't beat super/Turbocharging (on a road car, excluding nitrous which I don't think works well on the road)

Tom.