Piston / Conrod specs
Discussion
Just putting together the plan for the rebuild of my 4.0S. Budget won't stretch to a 4.3 so will be reusing original crank.
2 of the pistons are already in need of replacing but now the engine is apart, I can't help feeling I should replace the others too.
I guess what I'm needing advice on is what are my options for new pistons and rods?
Is it worth it for peace of mind, are there any performance improvements compared to the originals (late 2004 build)
Str8six will be doing the rebuild although Jasons been a bit odd in not really talking through the whole spec/options available so it'd be good to hear what others have chosen?
I've seen some references to different specs of pistons available, I beam or H beam rods, and lower friction piston rings??
2 of the pistons are already in need of replacing but now the engine is apart, I can't help feeling I should replace the others too.
I guess what I'm needing advice on is what are my options for new pistons and rods?
Is it worth it for peace of mind, are there any performance improvements compared to the originals (late 2004 build)
Str8six will be doing the rebuild although Jasons been a bit odd in not really talking through the whole spec/options available so it'd be good to hear what others have chosen?
I've seen some references to different specs of pistons available, I beam or H beam rods, and lower friction piston rings??
MrChips said:
Just putting together the plan for the rebuild of my 4.0S. Budget won't stretch to a 4.3 so will be reusing original crank.
2 of the pistons are already in need of replacing but now the engine is apart, I can't help feeling I should replace the others too.
I guess what I'm needing advice on is what are my options for new pistons and rods?
Is it worth it for peace of mind, are there any performance improvements compared to the originals (late 2004 build)
Str8six will be doing the rebuild although Jasons been a bit odd in not really talking through the whole spec/options available so it'd be good to hear what others have chosen?
I've seen some references to different specs of pistons available, I beam or H beam rods, and lower friction piston rings??
I went through the same thought process as you..in addition I was happy with the power of my 4.0S and just wanted to make sure it was strong and reliable.2 of the pistons are already in need of replacing but now the engine is apart, I can't help feeling I should replace the others too.
I guess what I'm needing advice on is what are my options for new pistons and rods?
Is it worth it for peace of mind, are there any performance improvements compared to the originals (late 2004 build)
Str8six will be doing the rebuild although Jasons been a bit odd in not really talking through the whole spec/options available so it'd be good to hear what others have chosen?
I've seen some references to different specs of pistons available, I beam or H beam rods, and lower friction piston rings??
The links below have more info:
http://www.pistonheads.com/gassing/topic.asp?h=0&a... Craft Con Rods and Pistons
http://www.pistonheads.com/gassing/topic.asp?h=0&a... engines
My understanding is that the TVR Indian rods (I beam)on pre-2005 are just about upto the job but can stretch..
The Indian rods were replaced by Linton rods (i beam)..see the link below:
http://www.pistonheads.com/gassing/topic.asp?h=0&a... for 'used' Linton conrods for a speed six 4.0&mid=184571
which were an improvement but are no lighter(Jason will be able to confirm if you have these).
The Carrillo forged steel conrods are the H-Beam's and are the ultimate for strength and lightness but they are over £1000 a set (same as used on the 4.3 and 4.5 upgrades)
I imagine Jason is being a bit odd because there are not many ways to cheaply upgrade the bottom end..and not much power to be gained.
I was lucky and managed to source some good used parts but it took some research...but this was probably a bit of a headache for Jason, with all the questions being asked and having to pull components in of unknown quality..and then being asked for a warranty..
The original 4.0s pistons were, by all accounts very good Italian sourced components..you might want to ask Jason about the Racing Green pistons which seem to be lighter..
TVR Power may also have some used billet steel cranks, which were part the original spec for the speeed six (not cast which does flex) ...
I can add a little more as i was in a similar position with my engine in bits at Jason's place and not really knowing where to start.
The pistons in my engine were the later 'coated' type and pretty good so i decided to leave these, the rods were the indian type but Jason looked them over and they were actually pretty good, they are typically a bad fit between cap and rod but mine were good - the next problem was the little end bearings, the originals were very worn so i had them replaced. I also upgraded the half time bearing which is a common failure point.
You may want to consider the later engine block too - better oilways and cooling and a stronger block, mine rund cooler and as a result im sure the risk of detonation is reduced.
Obviously the rest of the engine was also overhauled, cams and followers were replaced by RG before Jason got to it and they were still fine, but the valve seats, valve guides, piston rings, big end bearings etc etc all neeed replacing.
So really, bar the crank, (which was polished) rods (new little end bearings) pistons and head casting, everything else needed attention.
Id also agree that its probably difficult to advise where to go with the rebuild without spending significant cash (for marginal gains - you already have an s spec engine). New rods may be stronger but to what end if the indian rods are up to the job? I havent heard of any significantly better pistons that the coated 's' / red rose pistons or piston rings...but i will wait to be corrected!!!
The pistons in my engine were the later 'coated' type and pretty good so i decided to leave these, the rods were the indian type but Jason looked them over and they were actually pretty good, they are typically a bad fit between cap and rod but mine were good - the next problem was the little end bearings, the originals were very worn so i had them replaced. I also upgraded the half time bearing which is a common failure point.
You may want to consider the later engine block too - better oilways and cooling and a stronger block, mine rund cooler and as a result im sure the risk of detonation is reduced.
Obviously the rest of the engine was also overhauled, cams and followers were replaced by RG before Jason got to it and they were still fine, but the valve seats, valve guides, piston rings, big end bearings etc etc all neeed replacing.
So really, bar the crank, (which was polished) rods (new little end bearings) pistons and head casting, everything else needed attention.
Id also agree that its probably difficult to advise where to go with the rebuild without spending significant cash (for marginal gains - you already have an s spec engine). New rods may be stronger but to what end if the indian rods are up to the job? I havent heard of any significantly better pistons that the coated 's' / red rose pistons or piston rings...but i will wait to be corrected!!!
Edited by Robertjp on Monday 17th October 16:01
Cheers for the replies.
I've already given the go ahead for a new block as it has not only better oilways, but also coolant paths (running between cyl 5 and 6?). As my issue was detonation then this was a no-brainer for me. Maybe look to turn my old block into a coffee table or something!
Had some extra info from Jason and i've asked him to replace all 6 pistons. The ones he uses are high quality as far as I can make out, so as he's happy to warranty them for 5yrs, then i'm happy too.
My engine was one of the first mk2 S models built (December 2004) so we're not sure if the rods will be the earlier Indian ones or the later Linton ones. Jason's agreed with pretty much the sentiment here... if they're the Linton ones then they're fine, if there the Indian ones then less so, but we may still be able to re-use.
It appears there are a couple of options for replacements but only the H beam steel rods would be any lighter and the benefit would hardly be felt at all.
The difficult decision is just if I go down the route of changing pistons and rods, then i'm halfway to doing the 4.3 in terms of cost. Not that I really need any more power, just thinking that if I ever sold the car then the 4.3 would probably add a little to the sale price so make up the extra spent now. Difficult call though as I haven't seen any mk2 sold with the 4.3.
So it looks like if I do stay with the 4.0. I'll change the pistons to the str8six ones and then only replace the rods if necessary. I'd rather spend any extra money on anything else that crops up as part of the build, and then hopefully will have a small pot for a decat and bespoke mapping, maybe some airbox trumpets as well.
I've already given the go ahead for a new block as it has not only better oilways, but also coolant paths (running between cyl 5 and 6?). As my issue was detonation then this was a no-brainer for me. Maybe look to turn my old block into a coffee table or something!
Had some extra info from Jason and i've asked him to replace all 6 pistons. The ones he uses are high quality as far as I can make out, so as he's happy to warranty them for 5yrs, then i'm happy too.
My engine was one of the first mk2 S models built (December 2004) so we're not sure if the rods will be the earlier Indian ones or the later Linton ones. Jason's agreed with pretty much the sentiment here... if they're the Linton ones then they're fine, if there the Indian ones then less so, but we may still be able to re-use.
It appears there are a couple of options for replacements but only the H beam steel rods would be any lighter and the benefit would hardly be felt at all.
The difficult decision is just if I go down the route of changing pistons and rods, then i'm halfway to doing the 4.3 in terms of cost. Not that I really need any more power, just thinking that if I ever sold the car then the 4.3 would probably add a little to the sale price so make up the extra spent now. Difficult call though as I haven't seen any mk2 sold with the 4.3.
So it looks like if I do stay with the 4.0. I'll change the pistons to the str8six ones and then only replace the rods if necessary. I'd rather spend any extra money on anything else that crops up as part of the build, and then hopefully will have a small pot for a decat and bespoke mapping, maybe some airbox trumpets as well.
MrChips said:
Cheers for the replies.
I've already given the go ahead for a new block as it has not only better oilways, but also coolant paths (running between cyl 5 and 6?). As my issue was detonation then this was a no-brainer for me. Maybe look to turn my old block into a coffee table or something!
Had some extra info from Jason and i've asked him to replace all 6 pistons. The ones he uses are high quality as far as I can make out, so as he's happy to warranty them for 5yrs, then i'm happy too.
My engine was one of the first mk2 S models built (December 2004) so we're not sure if the rods will be the earlier Indian ones or the later Linton ones. Jason's agreed with pretty much the sentiment here... if they're the Linton ones then they're fine, if there the Indian ones then less so, but we may still be able to re-use.
It appears there are a couple of options for replacements but only the H beam steel rods would be any lighter and the benefit would hardly be felt at all.
The difficult decision is just if I go down the route of changing pistons and rods, then i'm halfway to doing the 4.3 in terms of cost. Not that I really need any more power, just thinking that if I ever sold the car then the 4.3 would probably add a little to the sale price so make up the extra spent now. Difficult call though as I haven't seen any mk2 sold with the 4.3.
So it looks like if I do stay with the 4.0. I'll change the pistons to the str8six ones and then only replace the rods if necessary. I'd rather spend any extra money on anything else that crops up as part of the build, and then hopefully will have a small pot for a decat and bespoke mapping, maybe some airbox trumpets as well.
Has anyone used titanium rods in a speed six rebuild?I've already given the go ahead for a new block as it has not only better oilways, but also coolant paths (running between cyl 5 and 6?). As my issue was detonation then this was a no-brainer for me. Maybe look to turn my old block into a coffee table or something!
Had some extra info from Jason and i've asked him to replace all 6 pistons. The ones he uses are high quality as far as I can make out, so as he's happy to warranty them for 5yrs, then i'm happy too.
My engine was one of the first mk2 S models built (December 2004) so we're not sure if the rods will be the earlier Indian ones or the later Linton ones. Jason's agreed with pretty much the sentiment here... if they're the Linton ones then they're fine, if there the Indian ones then less so, but we may still be able to re-use.
It appears there are a couple of options for replacements but only the H beam steel rods would be any lighter and the benefit would hardly be felt at all.
The difficult decision is just if I go down the route of changing pistons and rods, then i'm halfway to doing the 4.3 in terms of cost. Not that I really need any more power, just thinking that if I ever sold the car then the 4.3 would probably add a little to the sale price so make up the extra spent now. Difficult call though as I haven't seen any mk2 sold with the 4.3.
So it looks like if I do stay with the 4.0. I'll change the pistons to the str8six ones and then only replace the rods if necessary. I'd rather spend any extra money on anything else that crops up as part of the build, and then hopefully will have a small pot for a decat and bespoke mapping, maybe some airbox trumpets as well.
jcpgasoline said:
Has anyone used titanium rods in a speed six rebuild?
The answer is yes..but I have only seen pictures..Please see the thread below:
http://www.pistonheads.com/gassing/topic.asp?h=0&a... ,cast ,forged,crankshafts..anyone got any pics.
You should contact Dave at RND Engineering. He has the proper pistons and correctly weighted conrods you need. Also have a read of the latest Sprint Mag, there is a write-up on the whole subject. It makes you think why these companies still use the inferior components in some engine rebuilds.
Edited by Night Rider on Sunday 30th October 07:33
Gassing Station | Speed Six Engine | Top of Page | What's New | My Stuff