Stroker Questions

[Ish]

I've done lots of reading from some great resources, including the traditional books and forums, but I just have some questions:

 

I understand Kameari offers a stroker kit for a 3.2L L28 that utilizes an 85mm crankshaft, and their own pistons and rods...after some number crunching, they really like a really high compression ratio.  And I'm concerned about how high their kit sits atop the deck.  Rebello seems to offer a few different options as well.

 

I have an N42 block that needs to be bored at some point (some scoring from previous rebuild before I purchased the motor...looks like a ring notched the top of the cylinder wall pretty badly).  Right now, I'm just focusing on getting the car running as is before I seriously start building on it, but I'm just looking ahead...

 

I know the conventional 3.1L setup is 240Z rods with larger rod bolts, LD28 crank with 720/D21/240SX pistons, 89mm bore, and that combo yields a piston that's only 0.6mm above the deck--and that's pretty manageable with Cometic headgaskets and other headgaskets.  I've done some searching, and found lots of questions on various places without anyone really posting some serious results/experiences with an 85mm crank achieved by offset-grinding an LD28 crank.

 

Is there any tried setup that utilizes an 89mm piston, 85mm offset-ground crankshaft and some kind of connecting rod?  I'm not -as- concerned about rod/stroke ratio as long as it is 1.5:1 and above.  I'm just kind of feeling out and trying to learn from others.

[datzenmike]

I know the conventional 3.1L setup is 240Z rods with larger rod bolts, LD28 crank with 720/D21/240SX pistons, 89mm bore, and that combo yields a piston that's only 0.6mm above the deck--and that's pretty manageable with Cometic headgaskets and other headgaskets.  I've done some searching, and found lots of questions on various places without anyone really posting some serious results/experiences with an 85mm crank achieved by offset-grinding an LD28 crank.

 

Does not add up if assuming an 84.5mm stock stroke LD28 crank.

 

Deck height on the L28 block is 207.85mm ??? so crank/rod/piston must fit within this.

 

LD28 crank (84.5mm/2=).......... 42.25mm

L24 rod....................................133.0mm

KA or Z24 piston........................34.0mm

Total crank/rod/piston.............. 209.25mm or 1.4mm above the deck. Must have missed something here.

 

 

The KA24E piston is only 2.8cc. In addition just have a shop lath 1mm off the top outer edge and that 1.4mm becomes 0.4mmm  above the deck. Here are my KA24E pistons. Pin height is the same as the Z24 at 34mm...

 

 

 

Is there any tried setup that utilizes an 89mm piston, 85mm offset-ground crankshaft and some kind of connecting rod?  I'm not -as- concerned about rod/stroke ratio as long as it is 1.5:1 and above.  I'm just kind of feeling out and trying to learn from others.

 

 

The deck height on the L28 is 207.85mm correct? crank/rod/piston must fit this height without being more than about 0.3mm above the deck.

 

LD28 crank at 85mm stroke is... 42.5mm

KA24E piston pin height............ 34mm

L28 or L16 rod.........................130.2mm

Total........................................ 206.7 or 1.15mm below the deck. Do-able or mill 1mm off the deck for more compression.

 

 

I understand Kameari offers a stroker kit for a 3.2L L28 that utilizes an 85mm crankshaft, and their own pistons and rods...after some number crunching, they really like a really high compression ratio. And I'm concerned about how high their kit sits atop the deck. Rebello seems to offer a few different options as well.

I pick my teeth at their prices.

[datsunaholic]

I've often wondered why folks don't take the LD28 BLOCK, which has a higher deck like the L20B, and bore that out.  Then you could use the LD28 crank and rods, not worrying about excessive rod angle and overextended pistons.  You'd use the gasoline L-6 head and an L20B timing cover.  Or am I totally off on that?  Can you not bolt a L28 head to an LD28 block?

 

The other thought is to add a spacer block on top of the cylinder block, between the head and block.  Overbore the block and sleeve it (the sleeve would extend into the spacer), giving more deck height.  That's really a weird idea, but it comes from my experience with aircraft engines that use a separate crankcase, cylinder block, and head design.

[Lockleaf]

Some motorcycles also do that sort of "extended sleeve" as well. Never seen it in a car though. Interesting idea

[Doctor510]

I've often wondered why folks don't take the LD28 BLOCK, which has a higher deck like the L20B, and bore that out.  Then you could use the LD28 crank and rods, not worrying about excessive rod angle and overextended pistons.  You'd use the gasoline L-6 head and an L20B timing cover.  Or am I totally off on that?  Can you not bolt a L28 head to an LD28 block?

 

The other thought is to add a spacer block on top of the cylinder block, between the head and block.  Overbore the block and sleeve it (the sleeve would extend into the spacer), giving more deck height.  That's really a weird idea, but it comes from my experience with aircraft engines that use a separate crankcase, cylinder block, and head design.

 

MONEY  !!!!!!!!!!!!!!!!!!

[datsunaholic]

Well, yeah, I know sleeving and spacering is expensive, but when you look at what some folks spend to X-ray a block to find out if it can be overbored to an almost unsafe level, plus the cost of custom rods and pistons, offset grinding, ...  It's like folks that cut down the counterweights on a Z24 crank and clearance the block just so they can use a Z24 crank in a L16.  For way less you can use the Z24 block.

[Stoffregen Motorsports]

I've often wondered why folks don't take the LD28 BLOCK, which has a higher deck like the L20B, and bore that out.  Then you could use the LD28 crank and rods, not worrying about excessive rod angle and overextended pistons.  You'd use the gasoline L-6 head and an L20B timing cover.  Or am I totally off on that?  Can you not bolt a L28 head to an LD28 block?

I've done it. I built one using a billet crank, 6" rods and a turbo. It was a 3.2 liter.

 

It made almost 650hp on the dyno.

[Ranman72]

I've often wondered why folks don't take the LD28 BLOCK, which has a higher deck like the L20B, and bore that out.  Then you could use the LD28 crank and rods, not worrying about excessive rod angle and overextended pistons.  You'd use the gasoline L-6 head and an L20B timing cover.  Or am I totally off on that?  Can you not bolt a L28 head to an LD28 block?

 

The other thought is to add a spacer block on top of the cylinder block, between the head and block.  Overbore the block and sleeve it (the sleeve would extend into the spacer), giving more deck height.  That's really a weird idea, but it comes from my experience with aircraft engines that use a separate crankcase, cylinder block, and head design.

I dont think it would be considered a stroker with this combo 

[Stoffregen Motorsports]

Yeah, I guess something about the term "stroker" implies stuffing something that barely fits into a space it was not designed for.

 

Wow, out of context, the above could be read a few different ways...

[datsunaholic]

I get where making a "stroker" requires using the smaller block and the larger crank.  The L28E has a larger bore STOCK than an LD28, so without doing any extensive machine work it's the "easy" way to 3.0L.

 

I looked a litter further.  I guess the biggest problems with using the LD28 block is it can't be bored as much as an L28 block (some saying 86mm is the max, some saying 87, whereas some L28s can go to 89 but not many) but there's also the problem of the engine fitting under a stock hood due to the taller block.