V4 convert from alloy cast bore to wet liner !?
V4 convert from alloy cast bore to wet liner !?
(OP)
Hi All,
Just read this thread whilst trying to find some info for a project I'm working on.
Big Overbore Limitations
http://www.eng-tips.com/viewthread.cfm?qid=312712
Same scenario, but with an 800cc V4 motorcycle engine rather than the 400 in the original. Open deck cylinders.
I've already concluded that wet liners with a flange are the way to go & can source these from other models along with pistons etc, so thew only mods I would need to make would be custom modified head gaskets.
There are two questions I need answers too.
1. What is a safe minimum horizontal distance for a water tight seal with an MLS head gasket between the bore edge & the water cooling holes ?
2. What is the best way to seal the wet liner into the alloy crankcase to avoid water ingress to the crankcase ?
Thanks for any assistance with these questions.
Regards
Chris.
Just read this thread whilst trying to find some info for a project I'm working on.
Big Overbore Limitations
http://www.eng-tips.com/viewthread.cfm?qid=312712
Same scenario, but with an 800cc V4 motorcycle engine rather than the 400 in the original. Open deck cylinders.
I've already concluded that wet liners with a flange are the way to go & can source these from other models along with pistons etc, so thew only mods I would need to make would be custom modified head gaskets.
There are two questions I need answers too.
1. What is a safe minimum horizontal distance for a water tight seal with an MLS head gasket between the bore edge & the water cooling holes ?
2. What is the best way to seal the wet liner into the alloy crankcase to avoid water ingress to the crankcase ?
Thanks for any assistance with these questions.
Regards
Chris.





RE: V4 convert from alloy cast bore to wet liner !?
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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.
RE: V4 convert from alloy cast bore to wet liner !?
RE: V4 convert from alloy cast bore to wet liner !?
How do you propose to retain the sleeve at the bottom? An O-ring certainly won't do it; will there be a solid step for the sleeve to seat against?
jack vines
RE: V4 convert from alloy cast bore to wet liner !?
Bore out the old MMC liner, machine the base such that a stepped press fit to seat the bottom of the new wet liner with one or two O-rings to seal the crankcase from coolant contamination. The flange on the liner top will be skimmed to level everything & that will be the sealing face to the head. The liner will be supported over 2/3rds of it length in the crankcase, with only the top third as an open deck.
The liners I have in mind have 75mm bore (stock is 72) & may get bored to 76mm. That will leave 3mm wall thickness for a total diameter of 82mm. Current alloy cylinders are 88mm diameter OD, so the coolant capacity of the block will increase a bit which will be a small benefit & should help compensate for the reduced thermal conductivity of the iron wet liners.
Cheers
RE: V4 convert from alloy cast bore to wet liner !?
RE: V4 convert from alloy cast bore to wet liner !?
The wall thickness is 8mm as stock, but the MMC liner is castleated & 2.5mm wall thickness & due to casting movement from a block I cut up, it needs to be bored out to 78mm to clear the MMC fully. That would leave 5mm wall thickness, so possibly enough, possibly not.
A friend in New Zealand has taken my research & bored the MMC to 74mm for 825cc & added 20hp !
The wall can't be nikasil coated in the traditional manner as no company I've contacted can do a crankcase with 4 integrated bores.
I did find a very helpful Austrian company that do plasma deposition work for F1 etc & they could do the boring, plasma coating & final honing, but for 2000 euro ! so no :(
I have a local (ish) machine shop that is willing to under take the work to fit wet liners. They just did a wet liner replacement for a big bore twin cylinder for me.
RE: V4 convert from alloy cast bore to wet liner !?
RE: V4 convert from alloy cast bore to wet liner !?
RE: V4 convert from alloy cast bore to wet liner !?
RE: V4 convert from alloy cast bore to wet liner !?
RE: V4 convert from alloy cast bore to wet liner !?
RE: V4 convert from alloy cast bore to wet liner !?
You'll need a good support flange at the bottom. Suggest you load the flange to perhaps 50% of the compressive strength of the aluminum at maximum based on the bolt loads. Make the liners stand about .002"/.003" taller than the deck to start.