The V8 Owners Forum -

Hello all,

I’ve another project in the go.

I’m looking at building a 4.6/4.8 top hatted block for a super charged engine.

The current 3.9 has bent rods and melted pistons.

I’m looking for forged pistons and rods. Really struggling to find anything.

Are there any suppliers that could help?

Be using my early 36cc heads.

Thanks.

Paul V8 wrote: ↑

Thu Dec 22, 2022 7:35 am

Hello all,

I’ve another project in the go.

I’m looking at building a 4.6/4.8 top hatted block for a super charged engine.

The current 3.9 has bent rods and melted pistons.

I’m looking for forged pistons and rods. Really struggling to find anything.

Are there any suppliers that could help?

Be using my early 36cc heads.

Thanks.

how did they manage that damage ?

I ran a standard 4.6 bottom end for some time when I used my TT RV8 years ago, never had any concerns about those rods. I did eventually melt pistons, but that's entirely my fault. The actual pistons themselves were a decent design for standard pistons.

Although I'm sure standard 4.6 engine's aren't commonplace these days either

What about some of the stroker setups/kits Real Steel sell ?

John Eales keeps forged “blower” pistons on the shelf

John Eales was the 1st person I’ve tried and everyone since has said to go to him.

After several emails to him, he has said he has nothing suitable.

Real steel haven’t anything.

I think out piston issues were cause by incorrect fuelling, the rods, unsure of reason.

Previous engine was a 3.9, 8.13 pistons and 36cc heads.

post a picture of damage.

detonation can bend rods and destroy pistons, although usually pistons let go first.

Also depends under what circumstances it happened. Some rev limiters can also be harsh on rods.

Pistons should be easy, even if it meant getting some custom made. And push come to shove you could get rods made too.
Do real steel even do their stroker kit anymore ? Their own site doesn't seem to have it in their very ancient catalogue, although this listing whoever they are does

http://www.avrosystems.co.uk/realsteel/section1.pdf

Dave Powell at Performance Unlimited could source any custom stuff needed, but it can take a little while, and custom parts are not the cheapest route.

Here’s some pictures of the pistons.

Real steel don’t offer the stroker kit, but this would have been high compression.

Didn’t think it would be so hard to find parts for a top
Hatted 4.6.

Guess it’ll be custom.

I'd say just detonation.

Lean melting I'd usually more associate the sides of the piston melted too. But again, under what circumstances did it happen ? normal on load ? low rpm ? high rpm ? or on a rev limiter ?

As you say rods are also bent ? Cast pistons even if a pretty good design, are more fragile when it comes to detonation.

Also high/low is relative. I doubt I'd do any boosted engine much under 9.0:1 these days unless it was either very high boost or limited to poor fuel.

I don't think I'd ever do anything down around 8.0 or very low 8's. If using good fuel like ethanol or race fuel, you'd easily be well into the 9's or even 10's

I'd always try and find off the shelf solutions though. If you ever need to replace parts in the future, it can be a PITA when everything is custom.

What's your power goal?
My supercharged (centrifugal) 4.6 is using standard bottom end and all seems well. Running standard compression ratio for a 4.6 - with a light skim of the block and heads. I did biuret the heads and calculate it but i've long since forgotten the exact number! - It was more than 9:1 but less than 10:1 Probably around 9.5:1
Running upto 10psi and she loves it! I 'calculated this should be somewhere around 400bhp?
I tophat linered my block and at the time there was the option of changing the pistons but the cost was way higher - and everything I had read suggested the 4.6 had improved/stronger pistons over the 3.5/3.9 and would be fine for my humble power goals.

My fuel system is more than capable of supporting over 400 boosted horses using a Bosch 044 fuel pump and Bosch 968 (green giant) injectors. Also running wasted spark coil packs so have a decent mapable fuel & spark with wide band lambda sensor.

what fuel and spark are you using? and how much boost?

stevieturbo wrote: ↑

Sat Dec 24, 2022 10:45 am

I'd say just detonation.

Lean melting I'd usually more associate the sides of the piston melted too. But again, under what circumstances did it happen ? normal on load ? low rpm ? high rpm ? or on a rev limiter ?

The top pic he shared looked rather melted at the side to me?
Fuel system/lean AFR? maybe?

this might be interesting!

rover v8 4.8 short engine Forged Pistons 4.6 Top Hat Project. Currently £50. 5 days to go.

https://www.ebay.co.uk/itm/285119426860 ... media=COPY

That looks like its being sold by Rob of V8 Developments

SuperV8 wrote: ↑

Wed Jan 25, 2023 8:43 am

stevieturbo wrote: ↑

Sat Dec 24, 2022 10:45 am

I'd say just detonation.

Lean melting I'd usually more associate the sides of the piston melted too. But again, under what circumstances did it happen ? normal on load ? low rpm ? high rpm ? or on a rev limiter ?

The top pic he shared looked rather melted at the side to me?
Fuel system/lean AFR? maybe?

Still only the top ring land area.

Either way, it needs tuned properly.

I think that Real Steel catalogue may actually be up to date, judging by all the missing items compared to older printed catalogues that I have at home. Their stroker kits were actually quite interesting. I needed piston rings for one piston and contacted RS. They no longer had them but the code on the ring package had a part number that referred to an 90´s GM (?) V6 engine. Rings were naturally NLA. I found a set at ebay.com. So, instead of using a V8 set they used a 2 sets of V6 rings to make one V8 set with leftovers. Makes a lot of sense.

Rover engines and parts seem to be of dying breed. Parts availability is getting worse and worse.

Did a lot of the stroker kits not adapt and use chevy parts ?

Let's face it, it's a very old engine, not really that heavily used these days, and the market is getting smaller. Doesn't really warrant people developing a lot of parts.

If you're prepared to pay, it's very easy to get custom rods or pistons made to suit whatever, but it will not be cheap.

I'd have no issue using the OE 4.6 rods, and even pistons if you can get good ones. Or just get some custom pistons made. I don't think most Rover engines will make enough power/torque to have any major concerns about the rods

Or is there a database anywhere of rod measurements, as there's probably a rod already out there that could be very close ?

Interesting thread on forged pistons:

viewtopic.php?t=10232