Jump to content
HybridZ

STROKER MODS


Guest Anonymous

Recommended Posts

Guest Anonymous

I have a friend with a worn out 280 inj motor. I have a 84 diesel Maxima. We would like to build a stroker motor, but need to keep a lid on the budget. REALLY NEED HELP ASAP!!! eek2.gifugg.gifhail.gif

Link to comment
Share on other sites

What kind of budget are you looking at? The latest SportZ mag has a writeup on a budget stroker project using mostly used parts, and does it for about $2500. Do not think you can do a good one for less, as quality machine work is critical on this build up.

Link to comment
Share on other sites

Stroker short-rod engine or long-rod? That's the main decision you need to make because one involves using your 280Z block with the LD28 crank, and the other uses the LD28 block and crank. Read up on rod/stroke ratios and why a long-rod engine is better suited to high rpm use and tuning. The usual stroker L6 is an L28E block bored .120" over, to 89mm; LD28 crank; L24 or L16 rods (9mm bolts, 133mm length); Z24 or KA24 pistons, machined down a bit on top to reduce both compression ht and dish cc; and L28E cylinder head and gasket/cc of choice for desired compression ratio. Rod/stroke = 133/83 = 1.67.

An alternate stroker engine is LD28 block bored 0.60" over, to 86mm (or larger if using o.s. L28 pistons); LD28 crank; Z22E (E not S) rods (9mm bolts, 148.6mm length); L28E (p79) flat-top pistons; L28E cyl head of choice, head bolt holes drilled from 10mm to 12mm; BMW headbolts; L20B front cover; L20B timing chain; drill block boss for rear dipsick/rear sump use (Maxima is front sump); Z car oilpan. Rod/stroke = 148.6/83 = 1.79.

DAW

Link to comment
Share on other sites

DAW,

Well, I have never heard of a LD blocked stroker. I guess you could do it, but here are some thoughts. First, that only yields a 2992 cc motor, not much bigger than a stock L28. Second, a friend did a sonic bore test of a LD block to see how much material you could remove. The thought was with it being a diesel that "theoretically" it should have more "meat" to take out. Well, that proved incorrect, as it had the same average thickness as the L28, so a 3mm overbore was the max, even pushing it. And while the weight was fairly similar, you have all kinds of issues making the head work with the block not to mention the timing cover, etc... In the end, all you get is a different rod/stroke ratio, at nearly the cost of a stroker, if not more!

I would be interested to learn more about anyone who has done the LD block stroker - reasons, how it worked, etc..

-Bob Hanvey

Link to comment
Share on other sites

It's not a project for everyone. I've done an L28 stroker both ways. Why did Nissan increase the height of the L18 block when they increased the stroke? Rod/stroke. The L18 is essentially an L28 minus two cylinders (85mm vs 86mm bores, too), with rod/stroke = 130.4/79 = 1.65. Nissan retained the 85mm bore in going from the L18 to the L20B, but increased the stroke to 86mm and at the same time increased the block ht by the same distance as L28 vs LD28 ht, thus allowing use of longer rods which improved rod/stroke (L20B = 145.9/86 = 1.7). Nissan went further with factory long-rod engines by changing the 145.9 rod to 154.45 in the Z20E (car) engine which has a r/s = 1.77. The rod length differences are taken up by the differences in piston compression ht. When they further stroked the shortblock in the Z22 to 92mm, they increased the rod length in the car engine (Z22E) for a r/s = 1.62; while the truck engine (Z22S) kept L20B rods. With the increased stroke the r/s = 1.59 (a low r/s is OK for a pulling/lugging truck). In order to stroke that engine any further, they again had to increase the block ht (Z24 = 96mm stroke, r/s = 1.72), or the r/s would have been too low.

I used a mule car ('82 Maxima) for the initial LD28 block/crank stroker development. I took a diesel Maxima shortblock (84.5mm bore, 140mm rods with 23.5mm pins!) r/s = 1.69, and adapted an N42 head (10:1) with 280Z injection & 280ZX distributor. 280Z wrapped header with 3 into 2 3ft collectors into 2.5 exhaust. The engine runs smooth, strong & torquey, and reliable. The shortblock has 225K miles on it. I've driven it regularly for over a year. I don't go racing around in this Maxima but on occasion I've seen dropped jaws in the rearview mirror. This engine is going into a '72 240Z daily driver. My only concern is hood clearance in the Z due to the taller block (19.7mm). A turbo top-end assy combination onto an LD28 shortblock is next, then some overbore/longrod combinations using LD28 block. I think this taller block would have been the next natural evolution of the L6 by Nissan had they not gone with the VG30. DAW

Link to comment
Share on other sites

Typo above re Z20E connecting rod length: should be 152.45; not 154.45. BTW the truck (Z20S) engine rod is 148.6 (r/s = 1.73); while the car (Z20E) r/s = 1.78. The point is that a difference in r/s of .05 is significant enough that Nissan engineers separate rod & pistons to use in the same block, tailored to application.

DAW

Link to comment
Share on other sites

I've heard from a few different sources who have tackled this project that the LD28 block combo does NOT fit under a stock 240z hood when mounted in the stock location. Custom mounts and some creativity will be required.

 

Best of luck,

 

Michael

Link to comment
Share on other sites

Guest norm[T12SDSUD]

You want cheap and reliable?

 

Throw the diesel crank in yoru L28 and make sure you have crankthrow clearance on all the pistons. If lacking in clearance file a very small amount off the crank throw if its touchinga piston.

 

Shave the tops of the pistons .015" by hand on emery paper and run two stock head gaskets.DO NOT USE FEL PRO!

Try Victor Reinz headgaskets at your local NAPA.

 

I ran and raced this exact setup for 2 and 1/2 years with no problems. I ran a 12.88 @ 105.8 mph in the 1/4 mile with this daily driven Z engine.I finally broke a ring land after trying to rev her to 7600 rpm.

7100 rpm is max safe rpm's but 6800 max rpm's is recommended

 

After the overev I rebuilt it last year with stock pistons shaved .070" and 1 head gasket and am still driving her today.

 

Its cheap, its fast and it works.

 

Later,norm

Link to comment
Share on other sites

re LD28 block in 240-280Z, it was stated that it won't fit under the hood. I'm not sure about that, I checked hood clearance by sticking a stack of modeling clay on the highest point of the engine of my '72 with L28, sprayed vegetable oil on top of the clay to prevent sticking to the hood, and closed the hood. The LD28 with L28 head is 19.7mm taller than the L28 and although it's close, it looks like it will fit. If not, I've got a '67 Vette 427/435 hood scoop that looks good on the car. My concern is the clearance to the strut bar. There's no way that it's going to clear without modifying the strut bar and using a hood scoop; or, dropping the engine by slotting the mounts.

DAW

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...