LZ20 Stroker vs. Long rod?

[metalmonkey47]

Which do you guys think would be the best, streetable motor as well as power efficient with lots of potential?

 

I'm still playing with ideas for my LZ20E. I wanna make the decision so I can have any machining done early.

 

 

 

I know I can use the Z24 crank with cut down counterweights to achieve a displacement of 2.3L but at the same time, cut down on my potential for high revs.

I can use longer Z24 rods for a slightly shorter stroke and higher rev limit. With this, I was thinking about having the block bored to 89mm to accept larger Z24 pistons.

 

 

 

 

As far as induction, I still plan on using an L20 head and timing cover with a down draft Weber DGV. All my questions are still currently related to rotating assembly.

[Sealik]

Optimum block to bore to 89mm would be the Z22S (truck).......not sure of the Z20E????

[Farmer Joe]

honestly, if its going in your 210, then id just leave it a 2.0

 

compared to the a14 the lz20 will prolly blow your mind with prolly double the HP and TQ in stock form.

 

just hot tank it, have it balanced and put it back together with the L head...

[srljunkie38]

With that little carb you would be better of building a stroker. The carb just doesn't move enough air to support a higher revving long rod. I would use a z22 crank or the complete z22 short block. You will need to do some jetting too. Troy

[albyneau]

EVERYTHING is streetable power~ so I'm assuming you mean usable power for the street. Ignoring all engine specific data here, and going on practicality alone~

A high-reving motor moves it's ENTIRE power band up into the revs, and there will come a day (or two... or three... or...) when all those noisy revs just become tiresome, and take away from the driving experience. Torque, however, is always there, quietly waiting for you to feather the go-pedal and set you back in your seat. A low-revving motor reaches peak volumetric efficiency at a lower rpm: that lowered VE combined wih those lower rpms (fewer power strokes) mean fewer stops at the money-drinking gas machines.

 

Now for some "down-the-road" thoughts~ A properly built bottom-end is the foundation of ANY motor. Depenent on your choice of compression, a simple camshaft change could bring those revs back up if you so desire. It's more expensive to build a tweaker now and try to make it into a grunter later. Both options would likely require you end your romance with an undersized carb... Now close your eyes, and imagine trying to hear the stereo....

[d510addict]

What is a good carb choice for a lz20 then?

[Sealik]

EVERYTHING is streetable power~ so I'm assuming you mean usable power for the street. Ignoring all engine specific data here, and going on practicality alone~

A high-reving motor moves it's ENTIRE power band up into the revs, and there will come a day (or two... or three... or...) when all those noisy revs just become tiresome, and take away from the driving experience. Torque, however, is always there, quietly waiting for you to feather the go-pedal and set you back in your seat. A low-revving motor reaches peak volumetric efficiency at a lower rpm: that lowered VE combined wih those lower rpms (fewer power strokes) mean fewer stops at the money-drinking gas machines.

 

Now for some "down-the-road" thoughts~ A properly built bottom-end is the foundation of ANY motor. Depenent on your choice of compression, a simple camshaft change could bring those revs back up if you so desire. It's more expensive to build a tweaker now and try to make it into a grunter later. Both options would likely require you end your romance with an undersized carb... Now close your eyes, and imagine trying to hear the stereo....

 

Ya...stock L20B is 241ish duration..?.

Sooo....every 10 degrees of duration increases the power band up 500 RPM.

Maybe........... :D

[datzenmike]

85mm to 89mm (I dunnow), that's removing 2mm all the way round the cylinder 0.080"!

 

I suppose an LZ long rod and flattop piston block with an L head and some monster cam would go OK. But it wouldn't be much fun driving in stop and go.

 

Bore the block from 85mm to 89mm (I dunno), that's removing 2mm all the way round the cylinder 0.080"! Barely do able. Find a Z22 crank/rods and KA24E pistons and L head. LZ23. Not a high revving motor but lots of cubes and longer stroke for better bottom torque. Byron on the realm has an LZ22 with 135ish RWHP @ 6,500. Fuck, that 2 times the 210 minimum.

[metalmonkey47]

honestly, if its going in your 210, then id just leave it a 2.0

 

compared to the a14 the lz20 will prolly blow your mind with prolly double the HP and TQ in stock form.

 

just hot tank it, have it balanced and put it back together with the L head...

That was another thought, but I really wanna do something special with it while it's out. I figure, I can do any bottom end work NOW and not have to play with it later when I want to put a bigger cam, big side drafts. I'll gain more power from those mods then if I just leave it as a stock bottom end. Maybe It's best for the moment?

 

EVERYTHING is streetable power~ so I'm assuming you mean usable power for the street. Ignoring all engine specific data here, and going on practicality alone~

A high-reving motor moves it's ENTIRE power band up into the revs, and there will come a day (or two... or three... or...) when all those noisy revs just become tiresome, and take away from the driving experience. Torque, however, is always there, quietly waiting for you to feather the go-pedal and set you back in your seat. A low-revving motor reaches peak volumetric efficiency at a lower rpm: that lowered VE combined wih those lower rpms (fewer power strokes) mean fewer stops at the money-drinking gas machines.

 

Now for some "down-the-road" thoughts~ A properly built bottom-end is the foundation of ANY motor. Depenent on your choice of compression, a simple camshaft change could bring those revs back up if you so desire. It's more expensive to build a tweaker now and try to make it into a grunter later. Both options would likely require you end your romance with an undersized carb... Now close your eyes, and imagine trying to hear the stereo....

Well said I want something that on the weekends, I can take and play with but is still tolerable on the street. I want to keep a lower compression ratio since high compression doesn't seem like the best "streetable" option. Especially as prices of gas go higher and higher.

 

My thought was use L20 pistons that have a deeper dish, and use a close chambered U67 head. Just a simple header and down draft Weber until i can afford to do a little more with it in the future.

 

85mm to 89mm (I dunnow), that's removing 2mm all the way round the cylinder 0.080"!

 

I suppose an LZ long rod and flattop piston block with an L head and some monster cam would go OK. But it wouldn't be much fun driving in stop and go.

 

Bore the block from 85mm to 89mm (I dunno), that's removing 2mm all the way round the cylinder 0.080"! Barely do able. Find a Z22 crank/rods and KA24E pistons and L head. LZ23. Not a high revving motor but lots of cubes and longer stroke for better bottom torque. Byron on the realm has an LZ22 with 135ish RWHP @ 6,500. Fuck, that 2 times the 210 minimum.

 

So I suppose that doing a big bore isn't quite a good idea with cylinder walls as thin as they would be then. I don't plan on revving high on a daily basis, so perhaps I'd be better off with the longer stroke/bigger bore then short rods.

 

 

 

 

ALSO, while we're on subject, what head is this? I was told the valve cover is Z24, but it's a Z20 block. I know it's a NAPZ head but I'm trying to decide if it's Z20/22/24

[Sealik]

Pic of the intakes....?

4 plug Z20 or Z22

Heads are notched for injectors....Z24 is not.

Unless you do it yourself... :D

 

[metalmonkey47]

Pic of the intakes....?

4 plug Z20 or Z22.

 

I'll get back to you on that Don't have it on me

 

It's an 8 plug head. :P

[metalmonkey47]

Pic of the intakes....?

4 plug Z20(?) or Z22 are notched for injectors....Z24 is not.

Unless you do it yourself... :D

 

 

 

You edited on me

 

It must be a Z22 8 plug then because it's notched

 

 

[Sealik]

Ya...wasn't finished 'fine tuning' my reply.... :lol:

3rd pic looks like the exhaust plugs......are plugged.

 

Edit.....

 

I believe all 4 and 8 plug Z20(?)-Z22 are notched

[datzenmike]

Z24 head on top. square(ish) ports with somewhat rounded corners. Ignore the FI notches, I made them. Note the fuel pump boss is not machined for North Am.

 

Below is the Z22 head ROUND ports with factory notches. Had block off plate for fuel pump.

 

.

[metalmonkey47]

Hey Mike, what's the compression ratio of a stock L20B with a U67 head and stock dished pistons?

 

I found rock auto is selling L20B piston/ring combo at a closeout price of $20 and i wanted to run lower compression pistons. Not too low though

Edited April 27, 2011 by metalmonkey47

[datzenmike]

Hey Mike, what's the compression ratio of a stock L20B with a U67 head and stock dished pistons?

 

I found rock auto is selling L20B piston/ring combo at a closeout price of $20 and i wanted to run lower compression pistons. Not too low though

 

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