Engine Building Woes

[Mooghosty]

Today I finally relieved the call from the machine shop and the much awaited day had arrived; my LZ frankenmotor was done and ready to be picked up. So I went down to the  machine shop (Misison Auto Parts in San Antonio). They short block was machined and assembled with the parts I supplied, however I noticed an issue when I was inspecting the work. At TDC the pistons sit about a pinky width below deck height... Now that can't be right...

 

I think what happened was the ebay seller supplied me the wrong connecting rods (I never measured them before taking them into the shop). I think they sold me Z22E con rods in place of Z20E rods. Data from the Jason Grey ratsun thread says Late Z20E rods are 152.5mm long and Z22E rods are 149.5mm long. Which would account for the difference in piston and deck height. So my question is, do I roll with it as is since there's already money invested (I doubt I could get my money back on the wrong rods since they're already installed)? Or do I swap out the rods and buy the correct ones? 

If anyone is math inclined I would love to see a number crunch of the CR is with this current setup. 

 EDIT: If Ozdat is to be believed this will have a 7.860 CR :(

[datsunaholic]

A pinky width?  I don't know how big your pinky is, but that's 10 to 15 mm... WAY more than using a 3mm short rod would be.  Giving you compression somewhere in the 4 or 5s, I'd say.  I think you have L20B or early Z20S rods in there (145.9mm, same as an L20B), which would be around 6mm short.

[spottedog]

The end of my pinky is about  0.540" thats over half a inch! When your machinist put in the first piston and rod and saw this why didn't he call you!

Piston crown half a inch below the block deck WTF?

[dr.feltersnatch]

Somethin is way wrong here. No do not try to run it as is.

[dr.feltersnatch]

What block did you start with?

[datzenmike]

You supplied the parts so he assumed this is what you wanted. Always do your own work or have much better over sight. At least it can be disassembled and the correct rods or pistons used.

 

Exactly which LZ combo are you trying to do???

[dr.feltersnatch]

What crank do you have in there?

[Mooghosty]

Woah thanks for all the replies.

The machinist didn't call me because like datzenmike said, I supplied the parts and he assumed I knew what I was doing XD The LZ combo I was trying to make was a 2.1L "longrod" engine. I started with a L20 block with L20 crank, z22e pistons, and "z20e" rods. There are photos of the pistons I bought in a previous thread I made a while back. I'm thinking the issue here is the seriously wrong connecting rods.

I guess I should start looking for the correct rods online. I'll probably start on the classifieds here.

[datzenmike]

There were two Z22E pistons with 35.5mm and 32.1mm pin heights. The difference is 3.4mm almost the difference (3mm) between the 152.5mm and 149.5mm rods you mention.

 

Maybe the rods are 152.5mm and you have the shorter Z22 pistons???

[Mooghosty]

Now that would be interesting. It would account for the extra gap. 

I'll post some photos in a bit since I can't sleep.

[MikeRL411]

If all else fails, a supercharger?

[datzenmike]

Unfortunately it's 3mm the wrong way, sorry. Has to be the rod length.

[Mooghosty]

 

So I guess it's not quite a pinky width. It's still too low.

 

If all else fails, a supercharger?

 

Sounds good to me :D

 

 

 

 

[datzenmike]

The L20B block is 227.45mm tall

 

Half the crank stroke................... 43mm

L20B/Z22Sor early Z22E rods.... 145.9mm

Z22S or early Z22E pistons......... 35.5mm (the 32.1mm Z22E piston would be even worse)

adds to......................................224.0 or 3.45mm short... that's 0.1359" and looks about right

[KlassicMotion]

I would think if the shop was a good shop, knowing that you are piecing parts together, he would call you and verify that this is what you wanted.....  I can guarantee my shop would call me on such an issue.  But maybe that's the difference of me using the same shop for 20 years... How many times have you used this shop?

[datzenmike]

Send the L20B rods back and get the right ones or refund.

[KlassicMotion]

Maybe I'm confused here, what's the point of changing piston and rods, if your not changing the crank?

[Mooghosty]

 

I would think if the shop was a good shop, knowing that you are piecing parts together, he would call you and verify that this is what you wanted.....  I can guarantee my shop would call me on such an issue.  But maybe that's the difference of me using the same shop for 20 years... How many times have you used this shop?

This is the only time I've personally used this shop. They machined a friend's 440 mopar engine a while back, but we assembled that ourselves. Maybe they're more of a domestic v8 type shop.

 

 

Send the L20B rods back and get the right ones or refund.

 

I'll see what I can do about getting a refund. I wont be able to send these rods back because they're already installed, but the suppliers mistake did waste $100 of short block assembly. Who knows. Does anyone know of a good place to get these rods? I had a hard time finding this last set.

[Mooghosty]

 

I'm confused here, what's the point of changing piston and rods, if your not changing the crank?

 

Theoretically changing the pistons to shorter pistons and longer rods means a longer stroke, more displacement, and more power. There's more on it http://community.ratsun.net/topic/996-jason-grey-info/ if you want to read. It's the 4th post down that I was trying to build.

[datzenmike]

That motor has to come apart. It was never started so the rods were never used. Try and send back. THEY sent the wrong ones.

 

The 6" 152.5mm were used on the Z20E motor '80-.81 S110 200sx.and on the '83-'86 720 Z20S motor.  #12100-N8500 @ $99 each if you can still order them. Maybe somewhere else? Try wrecking yards.

 

 

 

Theoretically changing the pistons to shorter pistons and longer rods means a longer stroke, more displacement, and more power.

Shorter pin height and longer rods do not change displacement. Only a bore or stroke can do that.

[Mooghosty]

Thanks! 

[KlassicMotion]

So this is what you're going for?:

 

Long rod 2.1 L
I really like the possibilities for this 2.1L longrod motor. For a more in depth analysis of this motor click HERE.
Parts: L20B crank, Z22E pistons, Z20E rods in a Z22block or Z20/L20B block bored +2mm
s/2+r+p: 227.9mm
piston deck height: +0.05mm (above block)

 

Long rod 2.1L motor
parts: L20B or Z20 crank, Z22E pistons, Z20E rods in a Z22 block or +2mm bored L20B/Z20 block

This would be the best HIGH REVING, increased displacement, high compression, engine you could build from the mdium height L20B/Z20/Z22 size block. A "standard" L/Z 2.2 would have 5% more displacement and better midrange torque than this engine but the 2.1 longrod motor with 86mm fully counter weighted L20B/Z20 crank will suffer less vibraton at high RPM than the 1/2 counterbalanced Z22 crank and the hybrid 2.1L will have a slightly oversquare bore/stroke ratio, so better reving than the Z22 "truck engine".Rod to stroke ratio of the 2.1L motor is 1.77:1. Of all the possible L series motors only the L16 has a higher rod/stroke ratio (1.80:1). The long Z20E rods will reduce stress on pistons and help to make more HP at high RPM. The 1.5mm thick Z22E piston compression rings are thinner than 2.0mm L series piston rings so put less stress on the piston ring lands and are less prone to flutter at high RPM. In short, this motor should be a screamer if you build it well, balanced the rotating assembly, and use a suitable RPM cam, head and induction system.

The HOW TO MODIFY bible cautions against allowing the piston to come further than 0.30mm above the deck top, when built with 32.1mm pin height late Z22E pistons (1/82 and later), this motor when build would have the piston tops 0.05mm above. The "bad" honzowetz spec chart list Z22E pistons as having 32.5mm pin height so verify that you have the correct pistons.

With a high duration cam and high octane gas to reduce risk of detonation, you should be able to use a peanut chambered head to get higher CR and better chamber shape. The peanut head will be more detonation resistant for a given CR vs a open chambered head. If you are re-using old Z22E pistons, they will be 87mm. Engine displacement will be 2044cc.If you are buying new pistons, get Z22E pistons in +1mm oversize, 88mm and bore the L20B or Z20 block +3mm to 88mm or convert a Z22 block and bore only +1mm. Engine displacement with 88mm pistons will be 2092cc for a near true 2.1L motor. Did I mention that this motor make HP at high RPM!??

With 87mm bore, 86mm stroke producing 511cc of swept cylinder area, 9.32cc piston dish, 7.0cc gasket volume and the piston raised up above top of block by .05mm, using an open chambered head (U67 or A87) of 45.2cc volume, I calculate a CR of 9.31:1 or, if you used a 41cc peanut chambered head head, CR of 9.92:1. Check and verify the piston dish area and piston deck height!

Since planning this motor, I have realized that it should be possible to use VG30E pistons in this engine instead of the Z22E pistons. I am just not sure if the VG30E piston pins would be compatible with the L series connecting rods, I have seen conflicting specs for the VG30E piston pins that would/would not work depending on who is right. As far as I can tell, the earliest VG30E pistons used wristpins pressed into the rods while the later VG30E pistons use full floating rods retained by circlips.The pressed in pins should work on the L series rods (measure and verify!) of if you use full floating pistons, ensure adequate clearance between wristpin and conncerting rod hole and it will be necessary to drill oil supply holes in the connecting rod to splash lubricate the pin bore. The VG30E piston pin height is the same 31.75mm as Z20E pistons so the piston top would not protrude above the block thus no modifications to piston would be necessary. Compression ratio would be slightly higher with the VG30E pistons because they do not have the large piston dish of the Z22 pistons.

[laotsu]

looks like that's not a L20 block, notice the screw bosses around the oil intake? I would say it's a Zsomething block except it's clearly stamped L20b.

[KlassicMotion]

Theoretically changing the pistons to shorter pistons and longer rods means a longer stroke, more displacement, and more power. There's more on it http://community.ratsun.net/topic/996-jason-grey-info/ if you want to read. It's the 4th post down that I was trying to build.

 

There is no change in stroke without changing the crank, or offset-grinding the crank.  The only real displacement change you are getting from this engine build is from the overbore. 

 

Here is a quote from another forum:

"On paper, a longer rod, netting a higher rod/stroke ratio, is supposed to allow you to rev the engine higher at a safe level. This is because less force is being applied as a result of piston thrust (side loading) on the cylinder walls. also, the rod bearings will be taking less of a beating due to "better" attack angles on the power stroke which is likely the biggest worry, in my opinion, when wanting to rev a motor - spinning rod bearings.

 

Also, from another perspective with the longer rod, its going to dwell at TDC longer which means its going to sit at peak cylinder pressure longer.. I could see that as a good thing and a bad thing. The good - power loading. It hold peak cylinder pressure longer which could mean more power. The bad - If you have a hot motor, sitting at peak cylinder pressures is going to create more heat which induces hot spots which in turn increases the likelihood of pre-ignition."

 

It doesn't sound like this engine combo is what you were expecting it to be.  Before you go any further, you may want to reconsider what it is you are looking for out of your engine build.  Maybe you can use some of the parts you already have in combination with a different crank?....

[KlassicMotion]

looks like that's not a L20 block, notice the screw bosses around the oil intake? I would say it's a Zsomething block except it's clearly stamped L20b.

 

My 1980 L20B has those.