How much boring inside the cylinder liners?

[Schrade]

Some of you have bored your cylinders, but I wonder - how much CAN you open up the holes, before you're into the block?

.010? .030? .060???

[A26B]

For the LT5 open deck design, the original cylinder sleeves are made from aluminum and cannot be bored. The i.d. of the sleeves is coated with Nikasil, a very hard, durable material which requires a diamond hone to finish.

Increase of bore diameter is accomplished by replacing the original cylinder sleeve with an aftermarket design manufactured from high quality cast iron. Without machining the upper crankcase (block) to accept large o.d. sleeves, the upper limit of aftermarket cylinder sleeve bore diameter is normally considered to be 4.000" (0.100" larger than the stock bore of 3.900")

LT5 Open Deck Cylinder Sleeve

[Paul Workman]

The two approaches stemming from "FBI" territory to accomodate 4.125"* sleeves are caging the sleeves via the Haibeck fixture, or the AES Racing's closed deck sleeve system; both requiring considerable machining to the block.

*AES Racing claimes 4.165" sleeves possible yielding a 450 cid LT5.

Haibeck's open-deck, caged sleeve approach:




AES Racing's closed deck approach:




To my knowledge, there hasn't been enough LT5 samples of either design built to qualify yet as a valid sample size, far as reliability testing goes, except both concepts have been have been significantly vetted in other applications. And, the existing LT5 samples of each design have proven very reliable to date; examples of each making well over 680 NA chp!

P.

[rkreigh]

the haibeck fixture is really strong but requires a ton of work and cost to weld into the block.

how much work is needed to put in the AES liners and what do they cost?

really like the design of both but I believe the AES liners might be much more in line with my budget.

thinking of taking the 390 out to a bigger bore and going lower compression to run turbos.

or maybe leave it "as is" and run E85 full time. I believe I'm at 12-1 compression right now.

thanks!

[VetteVet]

Has anyone researched the possiblilty of oversized aluminum sleeves with Nikasil coating? I'm not sure if there is enough room available in the block to accomodate oversize aluminum liners without compromising coolant flow or having the walls of the liners too thin. The reason I ask is that there is a company in Wisconsin that does all of the Nikasil coating for Mercury Racing. We run Nikasil coated bores in the Formula I outboard motors that we race and they do all of our Nikasil coating work.

Jep

[Daniel_Mc]

Jep,

Like we spoke about I am also interested in how the cast iron heats and cools compared to the aluminum liners and aluminum block also what if any long term consequences will result from this?


Daniel

[VetteVet]

Daniel,

Outboards use aluminum blocks with steel sleeves for the production stuff. The high performance/racing stuff is all aluminum/nikasil.

I would imagine that the heat cycles with the dissimilar metals would contribute to head gasket fatigue/failure. Obviously not rapid, as proven by the cast iron sleeve motors that are out there, but the dissimilar thermal expansion coefficients have to take some kind of toll in head gasket durability. Doesn't Cometic have a gasket available for our motors? If so, that's what I would consider if I did a big-bore motor.

The bottom line is that as BMEP increases(resulting in higher thermal and mechanical loading), the dissimilar metals become more of an issue.

Jep

[Kevin]

i would think...based on my vast experience with cook wear....that the aluminum would heat up/cool down much faster than the cast iron