rebore from 4.6 to 5.0. Am I being diddled?
Discussion
spitfire4v8 said:
They're right to a point .. but the short stroke 5 litres are 4.6 bored to 4.8 then the crank offset ground to get the last 200cc aren't they ? In which case it might look to a casual observer like a 4.6, and have a 4.6 engine number ?
Thanks very much for the info. It's just that the garage have been cagey as to where they sourced the engine. I am worried they just gave me a 4.6 and hoped I wouldn't notice! spitfire4v8 said:
They're right to a point .. but the short stroke 5 litres are 4.6 bored to 4.8 then the crank offset ground to get the last 200cc aren't they ? In which case it might look to a casual observer like a 4.6, and have a 4.6 engine number ?
V8 Developements produce 5000cc this way. IMHO the best & strongest way of doing it (esp with crossbolted main bearings).If you have access to the short engine and a 6" steel rule, then it's easy enough to measure the 'capacity' of your new engine:
CC = l x 3.142 r2 x 8
where
l is the distance in cm the piston travels in the bore over one rev.
r2 is the radius of the bore in cm (squared).
and 8 is the number of cylinders.
What are your numbers?
CC = l x 3.142 r2 x 8
where
l is the distance in cm the piston travels in the bore over one rev.
r2 is the radius of the bore in cm (squared).
and 8 is the number of cylinders.
What are your numbers?
V8 GRF said:
It's quite possible for your engine to have a 4.x number (I assume you mean the number stamped in the block?) if it was a re-bore/rebuild of an older engine that started out with a different capacity.
Thanks. What I am finding so far is that if it goes to a reputable rebuild engineer, they will overwrite the factory engine number with their own number.Wicker Man said:
If you have access to the short engine and a 6" steel rule, then it's easy enough to measure the 'capacity' of your new engine:
CC = l x 3.142 r2 x 8
where
l is the distance in cm the piston travels in the bore over one rev.
r2 is the radius of the bore in cm (squared).
and 8 is the number of cylinders.
What are your numbers?
Cheers. I am loath to dismantle the engine that this point, but if it comes to that, it's good to know there is a simple calculation.CC = l x 3.142 r2 x 8
where
l is the distance in cm the piston travels in the bore over one rev.
r2 is the radius of the bore in cm (squared).
and 8 is the number of cylinders.
What are your numbers?
ChilliWhizz said:
If it's of any help, the V8D lump in mine was built in 2011, was the 'high performance' 5 litre, has a stroke of 86.36mm, 96mm bore, is cross bolted, and is externally identical to a 4.6 block.. Capacity is actually 5001cc 
Thanks. All I know is that I am very confused! They do indeed look identical, though it's been said to me that a 5.0 cannot be cross bolted. Punboy3 said:
ChilliWhizz said:
If it's of any help, the V8D lump in mine was built in 2011, was the 'high performance' 5 litre, has a stroke of 86.36mm, 96mm bore, is cross bolted, and is externally identical to a 4.6 block.. Capacity is actually 5001cc
Thanks. All I know is that I am very confused! They do indeed look identical, though it's been said to me that a 5.0 cannot be cross bolted. The original 5.0 engine in my Chimaera was not cross bolted, if I recall it didn't have the 'lugs' on the block casting that could be (some say inadvisably) drilled out for cross bolting.. also, the 'original' TVR 5.0 was based on the 3.9 lump not the 4.6.. hopefully I'm not talking bo**oxs
ChilliWhizz said:
Ah ok, sorry, should have said, the V8D 5.0 lumps (at least mine) are/were built from a new 4.6 Coscast block (which are cross bolted from new/as standard - I'm told), the crank is offset ground to give the 86.36mm stroke, and the cylinders are fitted with top hat liners to give the 96mm bore.
The original 5.0 engine in my Chimaera was not cross bolted, if I recall it didn't have the 'lugs' on the block casting that could be (some say inadvisably) drilled out for cross bolting.. also, the 'original' TVR 5.0 was based on the 3.9 lump not the 4.6.. hopefully I'm not talking bo**oxs
thanks a lot. it's starting to make a little sense now. I knew I should have paid more attention in metal work!The original 5.0 engine in my Chimaera was not cross bolted, if I recall it didn't have the 'lugs' on the block casting that could be (some say inadvisably) drilled out for cross bolting.. also, the 'original' TVR 5.0 was based on the 3.9 lump not the 4.6.. hopefully I'm not talking bo**oxs
BarnFind said:
Punboy3 said:
Thanks. All I know is that I am very confused! They do indeed look identical, though it's been said to me that a 5.0 cannot be cross bolted.
My 5 Litre is cross bolted.... ), I seem to recall reading somewhere that some of the later 5.0 cars were cross bolted..ChilliWhizz said:
May I ask what year it is? (not 2015 ), I seem to recall reading somewhere that some of the later 5.0 cars were cross bolted..
Well, the year is just one part of the mystery. I bought an engine and no paper work came with it on delivery. There appears to have been work done to it but the garage won't give me any clue as to how it became a 5.0 litre from being originally a 4.6. Anyway, I had to buy another engine because I can't trust the first one. Now I am negotiating to have compensation for the first one. All good clean fun! ), I seem to recall reading somewhere that some of the later 5.0 cars were cross bolted..Hope you get sorted OK....
Old thread from 2006 may throw a bit more light on the subject... Seems the (much) later 500's were based on the 4.6 (as fitted to the Chim 450's I be
http://www.pistonheads.com/gassing/topic.asp?h=33&...
Old thread from 2006 may throw a bit more light on the subject... Seems the (much) later 500's were based on the 4.6 (as fitted to the Chim 450's I be
http://www.pistonheads.com/gassing/topic.asp?h=33&...
Edited by ChilliWhizz on Tuesday 5th May 15:28
Punboy3 said:
Well, the year is just one part of the mystery. I bought an engine and no paper work came with it on delivery. There appears to have been work done to it but the garage won't give me any clue as to how it became a 5.0 litre from being originally a 4.6. Anyway, I had to buy another engine because I can't trust the first one. Now I am negotiating to have compensation for the first one. All good clean fun!
thanks will take a look.
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