XD Engine Upgrade

[discostew]

I would like to put together a 4.6 with 4.0 pistons and whatever camshaft I can come up with. Mostly for the boost in compression.
I personally don’t feel like the 6 tenths of a litre is worth spending much money on. Comparing these things to Chevy small blocks I grew up playing with. 5.7 is 350 cubes. 5.0 is 305 cubes, we called it a 3 oh nothing. I personally believe it’s hard to make power with less than 5.0 litres in a pushrod engine.

 

[4Runner]

The other thing to consider is the heads. They don’t flow well and getting heads that do, will set you back a fair amount.

 

[special ed]

OK, once again WHY? Why try and go out of the box and build a stroker thats going to take a lot of work to accomplish very little and not be a reliable engine. A 4.6 can pump close to 280hp without major modifications. Annabelle has stupid pulling power (she will climb up to big bear pulling a 5000lb trailer doing 45 mph) and im about to go even more with a full roller cam and rocker setup. Build a good 4.6 with a nice cam, maybe do a 4.0 piston swap and you will move your rover nicely without any weird grinds, sleeves pistons...

That said we get fascinated with how much. Oh i can build this or that. I always tell people i am not building a race engine and the focus is on power With reliability. something you can build once and it will last. So top hat sleeve the block, replace all the bearings, seals and rings. do a 4.0 piston to gain compression 1 point and put a nice cam in it. It will run great and is a tried and true build. If your not an engine builder and dont mind taking it apart time and time again like me (annabelle is a toy and an experiment) then you just want reliability and enough power.

 

[JohnB]

Even 6 years ago I could not get a timing gear that was made correct from aftermarket. Was lucky I could get one from Land Rover.

From what I've read you can't do that anymore.

Don't even get me started about my all makes cam shaft and lifter nightmare that almost took out my engine. Luckily the filter caught most of the crap.

 

[terryjm1]

I have a set of 4.6 pistons and crankshaft I’m planning to put in an early 4.0 block.

I have considered using the 4.0 pistons but my understanding is you then need to run fuel with an octane not readily available at typical fuel stations.

Anyone have personal experience with 4.0 pistons and a 4.6 crankshaft? Do you use premium fuel without any octane booster?

Also, I have gone back and forth on using a standard 4.6 camshaft or spending a little more for an uprated one. I was leaning toward a standard 4.6 cam but based on how much an uprated cam improved one of my old 3.5 engines, it makes me want to go that route again.

I am after a little more power but want to retain as much reliability as possible. I have a à low mileage 4.0 in one of my D1s and it is quite enough for everyday driving but it isn’t great pulling a trailer up hills (everywhere here) which has led me to the desire to go with the 4.6 ”conversion” in another one that has a tired engine. The tired one runs fine but is way down on power compared to the low mile one. I assume it is mostly due to a worn camshaft.

It will be a low budget build using mostly parts I already have. Everything I have is still within standard spec (cylinder bore, pistons, and crankshaft) so spending a bit on a camshaft isn’t major issue. I will also be using a brand new set of heads I sourced years ago. I don’t plan to do anything to the block except clean it and install new cam bearings. Of course, the new cam will get new lifters and with new everything that wears for the rest of the engine. I also have a pristine timing cover with nearly no wear in the oil pump casing.

Any thoughts, rude remarks, or other comments on my tentative plan?

 

[roverchef]

I have a set of 4.6 pistons and crankshaft I’m planning to put in an early 4.0 block.

I have considered using the 4.0 pistons but my understanding is you then need to run fuel with an octane not readily available at typical fuel stations.

Anyone have personal experience with 4.0 pistons and a 4.6 crankshaft? Do you use premium fuel without any octane booster?

Also, I have gone back and forth on using a standard 4.6 camshaft or spending a little more for an uprated one. I was leaning toward a standard 4.6 cam but based on how much an uprated cam improved one of my old 3.5 engines, it makes me want to go that route again.

I am after a little more power but want to retain as much reliability as possible. I have a à low mileage 4.0 in one of my D1s and it is quite enough for everyday driving but it isn’t great pulling a trailer up hills (everywhere here) which has led me to the desire to go with the 4.6 ”conversion” in another one that has a tired engine. The tired one runs fine but is way down on power compared to the low mile one. I assume it is mostly due to a worn camshaft.

It will be a low budget build using mostly parts I already have. Everything I have is still within standard spec (cylinder bore, pistons, and crankshaft) so spending a bit on a camshaft isn’t major issue. I will also be using a brand new set of heads I sourced years ago. I don’t plan to do anything to the block except clean it and install new cam bearings. Of course, the new cam will get new lifters and with new everything that wears for the rest of the engine. I also have a pristine timing cover with nearly no wear in the oil pump casing.

Any thoughts, rude remarks, or other comments on my tentative plan?

That is one of the best improvements you can do if you have the parts laying around. Using the 4.0 pistons with the 4.6 crank and rods is a great set-up and no you don't have to run anything other than premium pump gas which you should have been doing the whole time anyway. Give RPI a call or email and tell them what you are doing and they should be able to set you up with the correct grind for your new cam and you could also get Mr Adams to burn a matching set of chips to get everything you can out of your new set-up without sacrificing longevity/endurance. Save yourself a pile of $$ and get a valley pan gasket and a bunch of Dremel bits and start matching your new heads/intake with the gasket. Cut the trumpets too if you haven't already. Breathing makes a huge difference on these little V8's. Have fun.

 

[4Runner]

I also have the 4.0 pistons in a 4.6 platform. Just running premium gas will work. I also did the larger cam. I feel like an ECU tune is also needed for this set up. Port matching is great but hard on this set up. You never know how it’s going to work out till it’s completely torqued down.

 

[Tugela]

Any thoughts, rude remarks, or other comments on my tentative plan?

Yes! You're overlooking the obvious, if obscure factory option on early Discos in the UK market: the MPi engine!

To paraphrase Winston Churchill, which is something I sometimes do, "It has all of the virtues I dislike and none of the vices I admire."

 

[discostew]

I have a set of 4.6 pistons and crankshaft I’m planning to put in an early 4.0 block.

I have considered using the 4.0 pistons but my understanding is you then need to run fuel with an octane not readily available at typical fuel stations.

Anyone have personal experience with 4.0 pistons and a 4.6 crankshaft? Do you use premium fuel without any octane booster?

Also, I have gone back and forth on using a standard 4.6 camshaft or spending a little more for an uprated one. I was leaning toward a standard 4.6 cam but based on how much an uprated cam improved one of my old 3.5 engines, it makes me want to go that route again.

I am after a little more power but want to retain as much reliability as possible. I have a à low mileage 4.0 in one of my D1s and it is quite enough for everyday driving but it isn’t great pulling a trailer up hills (everywhere here) which has led me to the desire to go with the 4.6 ”conversion” in another one that has a tired engine. The tired one runs fine but is way down on power compared to the low mile one. I assume it is mostly due to a worn camshaft.

It will be a low budget build using mostly parts I already have. Everything I have is still within standard spec (cylinder bore, pistons, and crankshaft) so spending a bit on a camshaft isn’t major issue. I will also be using a brand new set of heads I sourced years ago. I don’t plan to do anything to the block except clean it and install new cam bearings. Of course, the new cam will get new lifters and with new everything that wears for the rest of the engine. I also have a pristine timing cover with nearly no wear in the oil pump casing.

Any thoughts, rude remarks, or other comments on my tentative plan?

Where do you get your cam bearings? I got some from Rover one time that was just a tube. I had to cut them and drill the oil hole in them. Damn nightmare

 

[terryjm1]

Where do you get your cam bearings? I got some from Rover one time that was just a tube. I had to cut them and drill the oil hole in them. Damn nightmare

Wow, that seems crazy. I haven’t looked around yet for this one but the last set I purchased, admittedly a long time ago, was nothing special, just a set from the local parts store ordered from their affiliated warehouse. They fit perfect and the cam spinned freely with no issues. My plan this time was to buy them from the Turner Engineering along with all the small bits (like stretch bolts). I figure using what they use for their builds is a safe bet.

 

[roverchef]

Wow, that seems crazy. I haven’t looked around yet for this one but the last set I purchased, admittedly a long time ago, was nothing special, just a set from the local parts store ordered from their affiliated warehouse. They fit perfect and the cam spinned freely with no issues. My plan this time was to buy them from the Turner Engineering along with all the small bits (like stretch bolts). I figure using what they use for their builds is a safe bet.

Stud it for best results or even use a set of the old school steel bolts with steel gaskets to bump the compression a wee bit but please don't use the stretch bolts on anything you care about. The threads in your block will thank you.

 

[p m]

Stud it for best results

IIRC, the nuts on the studs have to be re-torqued after some period. I wonder if anyone who's used studs is doing that.

 

[discostew]

Stud it for best results or even use a set of the old school steel bolts with steel gaskets to bump the compression a wee bit but please don't use the stretch bolts on anything you care about. The threads in your block will thank you.

What did Buick use for head bolts and torque specs?

 

[special ed]

IIRC, the nuts on the studs have to be re-torqued after some period. I wonder if anyone who's used studs is doing that.

Never retorqued studs. It would be interesting to check the ones in annabelle since they are going to be exposed soon. Ill see if they have changed at all. Heads probably have 1000 miles on them since i did them.

 

[terryjm1]

What did Buick use for head bolts and torque specs?

That is a great thought. I built an Oldsmobile version of the engine many years ago and I know they were not stretch bolts and did not require any re-torque. As a side note the Oldsmobile version used an extra head bolt but you could use the Buick heads or Rover heads. I believe the extra bolt was added to the Oldsmobile version because they had a factory turbo charger and mechanical fuel injection on a limited number of them. They used the engine in the Oldsmobile F85 which if memory serves me correct was the predecessor to the Cutlass. I put that engine in a TR7 and ran an Isky camshaft with an Offenhauser dual plane manifold with Holley 450 carburetor. It was a lot of fun!

 

[discostew]

That is a great thought. I built an Oldsmobile version of the engine many years ago and I know they were not stretch bolts and did not require any re-torque. As a side note the Oldsmobile version used an extra head bolt but you could use the Buick heads or Rover heads. I believe the extra bolt was added to the Oldsmobile version because they had a factory turbo charger and mechanical fuel injection on a limited number of them. They used the engine in the Oldsmobile F85 which if memory serves me correct was the predecessor to the Cutlass. I put that engine in a TR7 and ran an Isky camshaft with an Offenhauser dual plane manifold with Holley 450 carburetor. It was a lot of fun!

One thing I remember about the olds version is that they would not start at near zero outside temp. It would flood every time. We had to drag them in the shop and let them warm up.

 

[roverchef]

What did Buick use for head bolts and torque specs?

Buick used standard steel bolts.

That is what I used to use before the stud kits were available when building Rover motors. Usevthe steel gaskets to bump the compression a wee bit if needed.

 

[roverchef]

IIRC, the nuts on the studs have to be re-torqued after some period. I wonder if anyone who's used studs is doing that.

Over the yrs I have gone back and checked studs for accuracy on different clients motors and found they are just like every other single fastener out there...
Some are spot on and some are not.
Even when you use the stretch bolts not a single one of them is the same torque or tightness when installed. I've chalked that up as material and differing qualities of manufacturer.

 

[StangGT5]

I use ARP bolts from West Coast British. You have to call, but they're great bolts with none of the issues studs bring along.

My biggest improvement comes from head work. I have had noticeable improvements with ported heads on stock 4.6s. The machine shop I use in Atlanta will completely work a set for $850 (stock rebuild is $250). It's well worth it to me, especially on the exhaust side. The stock ports are pathetic.

I recently dissected the stage 3 RPI 4.6 in my RRC and found their heads are even more aggressive. They also fly-cut the pistons, but I've never had any PTV issues with entry level Crower cams and shaved heads. I did not measure the valves in the RPI heads, they could be bigger.

 

[DiscoClay]

Great thread. I was going over these options for a Disco-frame based M-37 (Dodge) project and orbited around engine options vs. cost for a long time.

It turned out that I could actually build a nice rover/buick engine for a disco sized truck for around $7500 bucks.. and a clean hemi or LS swap was not much cheaper, when I dialed in all the fiddlybits. The LS/Hemi is more powerful for sure, but not much cheaper.. and time/effort-wise.. the stroker rover seemed easier (given we weren't doing the machining).

We concluded it is worth building a naturally aspirated stroker to produce 270hp up to about 300hp with similar torque numbers (ft-lb). While this is really a "stretch goal" for the buick/rover engine and essentially a *floor* for the LS and hemi swap, it is a great power range for the disco. A 300hp NA D1 is a very peppy, competent, and confident wagon. 500hp is not necessary for this vehicle (for my intended use) though I have not driven a D1 with this much power so... I could be wrong

I am still researching roller cam efforts and am surprised these are not *common* upgrades for an engine with small block buick lifters and a history of flattening cam lobes. So much low and mid-range power can be made with a modern hydraulic roller that it just seems like a no-brainer to me.

On the subject of sleeves and big budget stuff:

Has anyone tried installing aluminum nikasil sleeves? I think Darton makes them (https://dartonsleeves.com/) and will customize for the Rover/Buick. Maybe even a MID conversion (if possible). Also interesting, would be to drop aluminum (nikasil) sleeves in. If I won the lottery I'd do it just because.
(https://dartonsleeves.com/)

From the D&D guy it is possible to make a 3.9 stroker with the Buick 300 crank (making 4.8L/293in) by boring 0.01 over (3.701) "with early 5.66 rods or modified Chevy rods and Ford 255 pistons".

The variety of options is really quite impressive

Great stroker info:

Displacement

D&D Fabrications is the Aluminum V8 Specialists Worldwide. Featuring Buick & Olds 215 CI and Rover 3.5, 3.9, 4.0, 4.2 and 4.6 liter engines.

aluminumv8.com

TA Performance makes aftermarket Buick 350 heads:
(https://www.taperformance.com/products.asp?cat=421)

TWS has fantastic info on building power with the rover v8:

TWS Motors

TWS Motors (formerly The Wedge Shop) has been serving the British car community since 1990. We are a provider of OEM and performance products for many British cars including: Triumph TR8, TR7, TR3, TR4, TR6, TR250, Spitfire, GT6, Land Rover, Jaguar, Lotus and MG. We carry a full line of OEM...

thewedgeshopstore.com

...but MAN are they pricey (note their, rare, roller cam is $2200: https://thewedgeshopstore.com/roller-cam-setup-rover-v8/)

RPI Engineering seems to have a lot of knowledge in this realm:

R P I International Ltd

At RPi Engineering we have be specialising in the Rover V8 engine for 30+ years. We supply not only parts but fully built engines world wide and also have full workshop facilities.

shop.v8engines.com

Roller cam info:

Hydraulic roller cam for Olds/Buick/Rover aluminum V8 - Don Terrill’s Speed-Talk

And lastly, I hope this one doesn't get me in trouble, the buickV8 forum has some great insights into cross-breed compatibilities and upgrades:

Small Block Tech

Curioius about the little brother? Ask here how to get your 215/300/340/350 some respect!

www.v8buick.com

And to answer the Why question... Why not?