Franken motors

[datzenmike]

Having ridden in Doug's LZ23 I can say it was a frigging blast! It goes!

 

LZ23 with Z24 pistons............ 8.40 open.... 8.825 closed head

LZ23 with KA24E pistons....... 9.78 open... 10.39 closed

[willz]

So lets say I don't care what the cost of the parts are, lets say I get aftermarket rods and pistons, I dont care what the cost is going to be to machine the block, wouldnt the L20b still have a better bore to stroke ratio than the LZ?

[Kirden]

L20B block bored to 86mm, unshrouded U67 head, Z22 crank, 152.5mm rods (N85 casting I beieve), and buick skyhawk pistons milled .5mm :P

[willz]

The U67 is an open chambered head correct? And the budget for this build is pretty much open as soon as I move and start my new job so spending $1500 on rods n pistons wont be a big deal

[datzenmike]

Depends if we are talking apples and oranges or not.

 

The 2.3 is an 89mm bore and Z22 crank or 89mm X 92mm  = 2,288cc motor usually with Z22/L20B rods and Z24 or KA24E pistons. The rod stroke ratio would be 1.58

 

Using an L20B block won't change anything.

[willz]

oh yea... god I feel like a dummy. Would the L20 block be more reliable than the Lz? I'm still worried about the whole cracked block issue

[Kirden]

Yes the U67 is open. The setup I just mentioned puts you over 10.5:1 CR without unshrouding the U67s valves. Closed chambered would be ~12:1 CR...

 

No real reason to go with forged pistons unless you plan on something crazy, which you probably won't need on an NA build. However, if you choose to, Venoila makes good pistons at about $100 each. CP will make rods for $350 each for exact replicas of the 152.5mm Z20 rods. By the time you dump that much into this motor you could either do a KA swap or but a bad assed boosted LZ.

 

OR, call up rebello and have them build you a 200hp LZ. The cost will be up there, probably more than a DIY SR swap, but you'd have an amazing engine built by pros.

[willz]

I would really like to build a (semi) period-correct motor for the truck. Its gotta be carb'd and I'd really like it to be something that would be more than peppy enough for an SCCA event.... like a modified street class hill climb event  :thumbup:

[datzenmike]

.

L20B block bored to 86mm, unshrouded U67 head, Z22 crank, 152.5mm rods (N85 casting I beieve), and buick skyhawk pistons milled .5mm :P

Well you would need pistons with a 30mm pin height or less. Could go as high as 30.25mm.to be 1/3mm above the deck.

 

 

 

 

Rod stroke ratio would be 1.65

[willz]

 truck has only 136k on the odometer

[datzenmike]

oh yea... god I feel like a dummy. Would the L20 block be more reliable than the Lz? I'm still worried about the whole cracked block issue

.

The Z22 blocks are fine as far as I know. Problems arose with the Z24 metallurgy.

[MicroMachinery]

The rods and cranks are already forged from the factory. Get yourself some good hardware(rod bolts by ARP), as they are the weak link in these motors. Your factory rods themselves should hold up to anything you'll throw at them. I've revved mine to the moon and as long as the bolts hold, you're in.

[datzenmike]

L20B block bored to 86mm, unshrouded U67 head, Z22 crank, 152.5mm rods (N85 casting I beieve), and buick skyhawk pistons milled .5mm :P

 

Yes the U67 is open. The setup I just mentioned puts you over 10.5:1 CR without unshrouding the U67s valves. Closed chambered would be ~12:1 CR...

.

I get 10.11 assuming the Skyhawk pistons are flattops.

[Kirden]

Thought L20s were 85mm blocks? Oh well, 86.5mm pistons give a tiny bit more room to play. The pin height on the skyhawk pistons is 29.75mm. I personally have to mill the block to get rid of some pesky rustso to be safe .5mm will be off the deck. Guess technically I could do .25 off the pistons but we'll see once the machinist gets all the parts.

[datzenmike]

Depends if we are talking apples and oranges or not.

 

The 2.3 is an 89mm bore and Z22 crank or 89mm X 92mm  = 2,288cc motor usually with Z22/L20B rods and Z24 or KA24E pistons. The rod stroke ratio would be 1.58

 

Using an L20B block won't change anything.

 

 

.

L20B block bored to 86mm, unshrouded U67 head, Z22 crank, 152.5mm rods (N85 casting I beieve), and buick skyhawk pistons milled .5mm :P

Well you would need pistons with a 30mm 29mm pin height or less. Could go as high as 30.25 29.20mm.to be 1/3mm above the deck.

 

 

 

 

Rod stroke ratio would be 1.65

.

 

I don't put much importance in rod stroke ratios. 1.50-2.0 you're good. This is like arguing over spoiler size and importance on a car that never sees over 80 MPH. At best it's a few % gain at extremely high RPMs by reducing rod and piston stress.

[Kirden]

Mike I think my math is off somewhere. I qouted the wrong numbers, but doesn't the L20B have 227.45mm deck height (within some tolerance)?

 

If so I'm counting:

92mm stoke

152.5mm rods

29.75mm (29.68ish) pistons

 

So 228.25ish? Looks like I'll have to I plan to take whatever is needed off the pistons so .75mm (ish) milled off would be .05 above deck height?

 

This is all hypothetical anyway. Once the machinist gets everything the real numbers will come out.

 

Back on track though, Rebello builds 200hp LZs and from my understanding most of the power comes from the head, so it may be worth contacting them for head work rather than looking at aftermarket rods and pistons. Bore the block to 87mm and have a 2.2l. 

 

As far as boring, personally I feel that boring any of the L/Z blocks to 89mm is sketchy at best, but if you pay for the sonic testing it may be safe. The walls just get pretty thin and you might get some distortion, it's definitely something I would send to rebello or ermish. Wouldn't trust a regular shop to bore these blocks that far over. Why not call rebello and see what advice they give?

[EricJB]

The rods and cranks are already forged from the factory. Get yourself some good hardware(rod bolts by ARP), as they are the weak link in these motors. Your factory rods themselves should hold up to anything you'll throw at them. I've revved mine to the moon and as long as the bolts hold, you're in.

 

I agree. The stock crank and rods are quality pieces. ARP rod bolts and your good. I ran my LZ with the rev limiter at 7000 for 2 years. The last race of the year I turned up to 7400, knowing I would retire the shortblock soon after.

Even launching with the pedal mashed at 7400 it didnt hurt it a bit. Ran the same number all day. Cant say the same for the stock pistons though.

[datzenmike]

Mike I think my math is off somewhere. I qouted the wrong numbers, but doesn't the L20B have 227.45mm deck height (within some tolerance)?

 

If so I'm counting:

92mm stoke

152.5mm rods

29.75mm (29.68ish) pistons

 

So 228.25ish? Looks like I'll have to I plan to take whatever is needed off the pistons so .75mm (ish) milled off would be .05 above deck height?

 

This is all hypothetical anyway. Once the machinist gets everything the real numbers will come out.

 

Back on track though, Rebello builds 200hp LZs and from my understanding most of the power comes from the head, so it may be worth contacting them for head work rather than looking at aftermarket rods and pistons. Bore the block to 87mm and have a 2.2l. 

 

As far as boring, personally I feel that boring any of the L/Z blocks to 89mm is sketchy at best, but if you pay for the sonic testing it may be safe. The walls just get pretty thin and you might get some distortion, it's definitely something I would send to rebello or ermish. Wouldn't trust a regular shop to bore these blocks that far over. Why not call rebello and see what advice they give?

 

 

Yes 152.5 + 46mm is 198.5 from 227.45mm is 28.95 (not 29.95) so the pin height needs to be around 29mm

[Sealik]

 

As far as boring, personally I feel that boring any of the L/Z blocks to 89mm is sketchy at best, but if you pay for the sonic testing it may be safe. The walls just get pretty thin and you might get some distortion, it's definitely something I would send to rebello or ermish. Wouldn't trust a regular shop to bore these blocks that far over. Why not call rebello and see what advice they give?

 

Apparently the early (82 and prior) Z22S  truck block metallugy is superior than the  Z22E (car) block and or.

That said....I've never heard of any issues boring either block to 89mm

[MicroMachinery]

Mine's fine.

[willz]

I'm lost on what I'm doing now

[datzenmike]

Ha ha

 

 

There is no wrong way to do this. Pick one and go. One is different from the other not better. If this helps...

 

2.1

Faster revving. Lighter internal parts

Higher revving. Long rods, shorter stroke and fully counter weighted (vibration free) crank.

Makes it's power at higher RPMs... IF it has a good breathing head, lots of carb and low restriction exhaust. More air equals more power.

Would show best performanse with a high numerical gear ratio like 4.375 or even higher

 

Parts harder to find.

Motor harder on parts.

Unless used with the aformentioned head and induction it will perform like a 2 liter motor.

 

2.3

Longer stroke equals more torque at lower revs.

Larger displacement means more air flow at lower speeds equals more power at lower speeds.

Even more power with good flowing head, carb(s) and exhaust.

In stock trim 6.5K red line is best. Not a big revver, doesn't need to be.

Will pull good with 3.70, 3.90 or 4.11 ratio gears.

 

Parts and machining much easier to find and cheaper

Makes good power without mods and easier on parts.

[willz]

Ok.. think I got this

block: LZ22

Z24 crank

L20 rods

ka24e piston

Bore block 2mms or to whatever it needs to be ha

 

U67 head with a boatload of porting and oversized valves, matched to custom intake and exhaust

Nice big low-mid range cam

 

Could I use a single sidedraft weber 45? Or would it be better to do the dual?

 

Arp stud kit

[Sealik]

Z22 crank...not a Z24

L20B or Z22 rods ,which most likely have to shaved on the small end

 

Duals are better than a single.

ARP kit for the con rods

Custom HG with 9 extra holes...7 in block

 

Etc....etc.

[willz]

Ive had a hard time finding a Z22 motor, so i think I might be better off with tearing down my L20 since they are easier to get a hold of in good condition. I might want to talk to my machinist and see if I could have the block sleeved as some extra peice of mind. Will probly be too much money in the long run but I'll see what says/price quote