5 litre piston rattle - what cost to fix?
Discussion
Mine also has the piston slap on overrun always been there for the 15 years ownership.
My understanding is that the 500 piston has very short skirts on the stroked standard TVR 500 engine, it is this that makes the 'marbles rolling around in a jar' sound when the piston is unloaded causing slap.
If something was out of tolerance then the noise would be worse under load, with different bearings becoming worse at low or high RPM
All IMHO
My understanding is that the 500 piston has very short skirts on the stroked standard TVR 500 engine, it is this that makes the 'marbles rolling around in a jar' sound when the piston is unloaded causing slap.
If something was out of tolerance then the noise would be worse under load, with different bearings becoming worse at low or high RPM
All IMHO
Unfortunately it looks like another bottom end rebuild.
There is a lot of talk about the 500 design and reliability. Before rebuilding mine, which had no appreciable bottom end wear, I spoke at some length to John Eales. He was averse to re-using the TVR pistons. He also advised internally balancing. His experience, considerable, was that no 500 he had rebuilt with new pistons and internally balanced had problems or failed.
On this advice I had them pressure test the block and that being sound, rebore to 94.5 mm (from memory!), supply new pistons to suit fitted to existing rods and the rotating assembly all balanced, and block cross bolted. I assembled the engine. His charge was very reasonable. No problems to date. This was the sensible and economic approach for me.
Dougal.
There is a lot of talk about the 500 design and reliability. Before rebuilding mine, which had no appreciable bottom end wear, I spoke at some length to John Eales. He was averse to re-using the TVR pistons. He also advised internally balancing. His experience, considerable, was that no 500 he had rebuilt with new pistons and internally balanced had problems or failed.
On this advice I had them pressure test the block and that being sound, rebore to 94.5 mm (from memory!), supply new pistons to suit fitted to existing rods and the rotating assembly all balanced, and block cross bolted. I assembled the engine. His charge was very reasonable. No problems to date. This was the sensible and economic approach for me.
Dougal.
If it's making a noise when cold ,what is the noise ? The internals must be knocking against each other .
Mine was built by one of the top players and would cost you 8k today .
It's a 5l with a 96 bore with an offset ground 4. 6 crank .
What is the heavy metallic knock ?
It's done two maybe three track days and I only did s few laps then rested the car .
Its been used st pod and dusky maybe half a dozen times and I have never reved it untill warm.
I have used even vr1 or 15w60 fully synthetic penrite.
Its cet annoying .
After about two minutes on idle the sound goes but if I put it under load in a high gear I can hear it .
Bloody annoying and frustrating .
Mine was built by one of the top players and would cost you 8k today .
It's a 5l with a 96 bore with an offset ground 4. 6 crank .
What is the heavy metallic knock ?
It's done two maybe three track days and I only did s few laps then rested the car .
Its been used st pod and dusky maybe half a dozen times and I have never reved it untill warm.
I have used even vr1 or 15w60 fully synthetic penrite.
Its cet annoying .
After about two minutes on idle the sound goes but if I put it under load in a high gear I can hear it .
Bloody annoying and frustrating .
SILICONEKID 357HP said:
If it's making a noise when cold ,what is the noise ? The internals must be knocking against each other .
Mine was built by one of the top players and would cost you 8k today .
It's a 5l with a 96 bore with an offset ground 4. 6 crank .
What is the heavy metallic knock ?
It's done two maybe three track days and I only did s few laps then rested the car .
Its been used st pod and dusky maybe half a dozen times and I have never reved it untill warm.
I have used even vr1 or 15w60 fully synthetic penrite.
Its cet annoying .
After about two minutes on idle the sound goes but if I put it under load in a high gear I can hear it .
Bloody annoying and frustrating .
My Cerb engine has a knock - worse when cold and quietens when hot .. Dom did the bottom end machining and supplied the parts and I built it. I was gutted. So gutted in fact that I paid AJP guru Andy at APM to take it to bits and sort the knocking out .. he said he couldn't find anything wrong with any of it so put it back together.Mine was built by one of the top players and would cost you 8k today .
It's a 5l with a 96 bore with an offset ground 4. 6 crank .
What is the heavy metallic knock ?
It's done two maybe three track days and I only did s few laps then rested the car .
Its been used st pod and dusky maybe half a dozen times and I have never reved it untill warm.
I have used even vr1 or 15w60 fully synthetic penrite.
Its cet annoying .
After about two minutes on idle the sound goes but if I put it under load in a high gear I can hear it .
Bloody annoying and frustrating .
Not unsurprisingly it still has the exact same knock. Double out of pocket, double gutted.
Sometimes you just have to live with it. We'd all like to have quiet engines, and many of them are quiet it's true, but I've heard some awful sounding AJPs from the big names costing teens of thousands of pounds .. strangely it doesn't seem to affect them and they go for tens of thousands of miles making noises and performing faultlessly.
In your instance - TVR never got all the 5 litre RV8s to be quiet when new - some of those were as rough as a bear's bottom. I'm surprised there weren't more complaints about the tvr 5 litre engine when new, some of them really were awful. The worst were the later engines - the early ones were much smoother for some reason.
It's a shame - especially in your case where it was at one time a quiet RV8 engine so something has changed, but unless you want to spend more money you are going to have to live with it I reckon. Changing oils isn't a fix, it's a sticking plaster.
You've got to make a decision .. live with it, fix it, or sell it. Posting about it on forums but not actually taking action won't fix anything.
Daz's engine is one of Rob's short stroke 5.0s
That noise could be anything. I had a cam bearing become loose from a previous engine for no reason at all. Yours would require a strip and investigation if you were so in the mood. I probably would do that very thing as Joolz did.
Even though these engines are quite good for what they are, you can't compare them with a fairly modern engine in my opinion. My old 1.8 turbo VAG engine would sing flat out all day long and ask for more and yet would idle at a whisper.
That noise could be anything. I had a cam bearing become loose from a previous engine for no reason at all. Yours would require a strip and investigation if you were so in the mood. I probably would do that very thing as Joolz did.
Even though these engines are quite good for what they are, you can't compare them with a fairly modern engine in my opinion. My old 1.8 turbo VAG engine would sing flat out all day long and ask for more and yet would idle at a whisper.
The other way to look at this is that human beings have been building internal combustion engines that don't make such noises for well over 100 years now, internal combustion engine design is hardly a new science and its not like the old Rover V8 is an unknown entity or a cutting edge design, if an engine builder has failed to build a quiet version of a very well understood late 1950's designed V8 that was in production for 40 years or more quite frankly he's got something fundamentally wrong. In the case of TVRs 5.0 litre variant of this super well understood engine, that may simply be because the engine builder is unknowingly repeated the exact same mistakes TVR did when they created their 5.0 recipe.
The thing is if you call yourself an engine builder and especially if you call yourself a specialist in the Rover V8, there really are no excuses for repeating the mistakes of others on such a well known engine. If TVR got their gudgeon pin offset sums wrong or worse still never really did those calculations correctly in the first place when choosing the pistons for their stroker kit, there's really no reason why over 20 years later a so called Rover V8 engine specialist need repeat the exact same mistake.
Well there are a few reasons actually...
1. He simply didn't think about what he was doing
2. He didn't understand what he was doing
3. He failed to learn from the mistakes made by TVR
When its quite clear 3.5, 4.0 & 4.6 litre variants of this super well known engine don't rattle on the overrun it doesn't take a genius to realise we need to study the components used in TVR's 5.0 litre variant that are unique to that engine recipe. If you then consider what over 100 years of internal combustion engine knowledge points to when any engine rattles on the overrun, it's quite clear the focus of suspicion lands fairly and squarely in the area of the little end.
The primary reason for offsetting the gudgeon pin from the centre line of the piston is to prevent the piston skirt coming into contact with the cylinder bore after TDC (piston slap), but there's a lot more to it than that. The direction of crankshaft rotation dictates when the engine is under power there will always be an increase in load on the thrust side of the piston crown as it passes over TDC, conversely that load will shift back towards the piston centre line when you unload the engine, ie on the overrun.
These shifting loads are the unavoidable consequence of turning reciprocating motion into rotational motion especially when engine speeds and cylinder pressures are expected to vary, with the exception of the wankel rotary engine all internal combustion engines must be designed to manage these shifting loads. Since the early days of the steam locomotives the way engineers have been solving this issue is to offset the gudgeon pin, and there are well known mathematic formulas that were developed over a hundred years ago to help anyone get this critical offset correct.
No ship Sherlock... there's a reason why you will always find 'Front' or the '>' symbol on the crown of a piston, ignoring it and fitting the piston back to front would be to reverse the gudgeon pin offset carefully calculated by the highly skilled engine designer with disastrous consequences for your engine, so the question is were TVR highly skilled engine designers who understood the mathematical formulas used to calculate gudgeon pin offset or did they just cook up an stroker kit to create the 5.0 litre without really doing the maths
Maybe they did and maybe they didn't, personally I suspect what they were trying to achieve within the restrictions of the basic engine architecture forced some real geometry compromises they understood, but chose to accept! If you really study what they did its quite clear it sits right on the bleeding edge of acceptable, certainly if any half competent engine designer started with a clean sheet of paper he would never design an engine with the bore and stroke combination TVR ended up with when they stroked old Rover to 5.0 litres, there's a reason Land Rover stopped at 4.6 litres folks
All these RV8 engine builders are doing when they serve up rattling 5.0 litre TVR Rover V8 engines is blindly repeating TVR's compromised design, they repeat the geometry issues on reused pistons with slight wear in the little end that on any other engine would be deemed within tolerance, they then finish it off with nice tight rings and refreshed cylinder heads that will likely have been skimmed too. What they end up with are all the original inherent geometry compromises of TVR's recipe, but now with lots more cylinder pressure acting on that worn and fundamentally poorly offset little end.
No wonder they rattle on the overrun
The thing is if you call yourself an engine builder and especially if you call yourself a specialist in the Rover V8, there really are no excuses for repeating the mistakes of others on such a well known engine. If TVR got their gudgeon pin offset sums wrong or worse still never really did those calculations correctly in the first place when choosing the pistons for their stroker kit, there's really no reason why over 20 years later a so called Rover V8 engine specialist need repeat the exact same mistake.
Well there are a few reasons actually...
1. He simply didn't think about what he was doing
2. He didn't understand what he was doing
3. He failed to learn from the mistakes made by TVR
When its quite clear 3.5, 4.0 & 4.6 litre variants of this super well known engine don't rattle on the overrun it doesn't take a genius to realise we need to study the components used in TVR's 5.0 litre variant that are unique to that engine recipe. If you then consider what over 100 years of internal combustion engine knowledge points to when any engine rattles on the overrun, it's quite clear the focus of suspicion lands fairly and squarely in the area of the little end.
The primary reason for offsetting the gudgeon pin from the centre line of the piston is to prevent the piston skirt coming into contact with the cylinder bore after TDC (piston slap), but there's a lot more to it than that. The direction of crankshaft rotation dictates when the engine is under power there will always be an increase in load on the thrust side of the piston crown as it passes over TDC, conversely that load will shift back towards the piston centre line when you unload the engine, ie on the overrun.
These shifting loads are the unavoidable consequence of turning reciprocating motion into rotational motion especially when engine speeds and cylinder pressures are expected to vary, with the exception of the wankel rotary engine all internal combustion engines must be designed to manage these shifting loads. Since the early days of the steam locomotives the way engineers have been solving this issue is to offset the gudgeon pin, and there are well known mathematic formulas that were developed over a hundred years ago to help anyone get this critical offset correct.
No ship Sherlock... there's a reason why you will always find 'Front' or the '>' symbol on the crown of a piston, ignoring it and fitting the piston back to front would be to reverse the gudgeon pin offset carefully calculated by the highly skilled engine designer with disastrous consequences for your engine, so the question is were TVR highly skilled engine designers who understood the mathematical formulas used to calculate gudgeon pin offset or did they just cook up an stroker kit to create the 5.0 litre without really doing the maths
Maybe they did and maybe they didn't, personally I suspect what they were trying to achieve within the restrictions of the basic engine architecture forced some real geometry compromises they understood, but chose to accept! If you really study what they did its quite clear it sits right on the bleeding edge of acceptable, certainly if any half competent engine designer started with a clean sheet of paper he would never design an engine with the bore and stroke combination TVR ended up with when they stroked old Rover to 5.0 litres, there's a reason Land Rover stopped at 4.6 litres folks
All these RV8 engine builders are doing when they serve up rattling 5.0 litre TVR Rover V8 engines is blindly repeating TVR's compromised design, they repeat the geometry issues on reused pistons with slight wear in the little end that on any other engine would be deemed within tolerance, they then finish it off with nice tight rings and refreshed cylinder heads that will likely have been skimmed too. What they end up with are all the original inherent geometry compromises of TVR's recipe, but now with lots more cylinder pressure acting on that worn and fundamentally poorly offset little end.
No wonder they rattle on the overrun
Daz, is it pinking? Sounds to me as if it had knock/detonation under load in which case it needs setting up on the rollers.
Is the noise at cold the same noise you hear when hot and under load? A noise at cold could be anything, maybe a follower assuming your's are hydraulic.
Is the noise at cold the same noise you hear when hot and under load? A noise at cold could be anything, maybe a follower assuming your's are hydraulic.
Edited by Boosted LS1 on Friday 7th February 10:21
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