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Rebuilding my L20B


ErickwithnoK

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best to build a head and maybe whole motor on side. so to keep your truck running. I sen a lot of 521s go out to swap KA motor just for a bad carb and then you never hear from the guy again

 

L motors are EZ and fairly cheap t keep running

 

Your a newbie on here and we ALL can tell. by the question your asking.  having a motor on the side you get to ask lots of question and your truck will still be running. I get more thumbs up by driving my stock slow truck than a broke one in the yard.

 

Im sure if you call Isky or Schneider tha last guy will be the one you believe. If anything those cams are in a corner waiting to get thrown away cause there is no market.

Go by the people on here.

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best to build a head and maybe whole motor on side. so to keep your truck running. I sen a lot of 521s go out to swap KA motor just for a bad carb and then you never hear from the guy again

 

L motors are EZ and fairly cheap t keep running

 

Your a newbie on here and we ALL can tell. by the question your asking. having a motor on the side you get to ask lots of question and your truck will still be running. I get more thumbs up by driving my stock slow truck than a broke one in the yard.

 

Im sure if you call Isky or Schneider tha last guy will be the one you believe. If anything those cams are in a corner waiting to get thrown away cause there is no market.

Go by the people on here.

I'm just gonna build with what I have, I don't mind if my truck is out of commission for a couple months.

 

I'll call isky and see if I can get a good deal on a mild cam when the time comes, thanks for the tip

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I was offered an l18 shortblock with l16 rods minus the pistons, as well as a w53 ported head minus the camshaft, along with new valve springs from Isky, for $500. 

 

I can verify the guy who is offering it is a good dude who wouldn't sell me junk. 

 

It is the makings of the l18 in this (very popular) post:

 

http://community.ratsun.net/topic/996-jason-grey-info/page-1

 

"Long rod L18 
flattop Z20S pistons and peanut chamber head for 9.7:1 CR, better rod/stroke ratio for higher RPM. 
Parts: L18 crank, L18 block, L16 rods, Z20S pistons 
s/2+r+p: 207.66mm 
piston deck height: -0.29 (below deck)"

 

As a novice who doesn't know the value of used parts this seems like a good deal that will allow me to do what all of you have been telling me to do: Build a motor on the side.

 

What are the differences between this new plan compared to using my l20?

 

Is a bored l18 @ 86mm the same displacement as a bored l20? 

 

What pieces/processes am I missing to put this thing together?

 

Is this a good financial decision?

 

Is this a streetable motor?

 

Thanks for the opinions.

 

 

 

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First there is no replacement for displacement. Run the largest engine you can find.

 

$500 for that seems a bit high. It's really a bunch of left over parts.

 

L18 block, 86mm 85mm bore and crank is still and L18 displacement. With L16 rods it is simply a 'long rod' engine.

 

 

You will need the Z20S/E pistons. If the L18 block is well used you really should over bore to the next available Z20 over size pistons. Then you have an L18.... still. Then you need a cam for it.

 

An L20B would easily be a better choice unless you add multiple carbs and a crazy cam.

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First there is no replacement for displacement. Run the largest engine you can find.

 

$500 for that seems a bit high. It's really a bunch of left over parts.

 

L18 block, 86mm 85mm bore and crank is still and L18 displacement. With L16 rods it is simply a 'long rod' engine.

 

 

You will need the Z20S/E pistons. If the L18 block is well used you really should over bore to the next available Z20 over size pistons. Then you have an L18.... still. Then you need a cam for it.

 

An L20B would easily be a better choice unless you add multiple carbs and a crazy cam.

 

Thanks Mike. I believe you and more "displacement = better" makes sense to me. Plus I already have an L20. 

 

That being said, why is the L18 considered a desirable motor? I seem to remember people talking about the L18 like it was preferred. That's one of the reasons I was interested with this. What are the positives?

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L18 is 85mm. The pistons needed for that would be 86mm Z20S flattops.

 

 

This is the motor I have been wanting to build for quite some time...and have all the parts for minus the pistons.

 

I like the idea of it being a better revving motor...even more than the L16. Getting the head to breathe, as stated in this thread already, just gets more power through it.

 

Stock L20 build? Boring. Long rod 19, maybe not as exotic as some of the other Frankenstein motors, but I'd bet it would still be a rippin' little motor.

 

I think dyslexicdime said he had one of these and could push it past 9,000rpms.

If this motor could breathe at that speed-look out!

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Need coffee, yeah 85mm same as L20B/Z20

 

There's no right or wrong in selecting an engine. Just choices.

 

Displacement makes more power with less effort, and sooner at lower speeds than a smaller displacement. You can get the same power from a smaller engine but it's way more work and strain on it. There may be no option than building up a smaller engine if you are racing in a certain displacement class, otherwise (opinion only) you're making 7 the hard way.

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L18 is 85mm. The pistons needed for that would be 86mm Z20S flattops.

 

 

This is the motor I have been wanting to build for quite some time...and have all the parts for minus the pistons.

 

I like the idea of it being a better revving motor...even more than the L16. Getting the head to breathe, as stated in this thread already, just gets more power through it.

 

Stock L20 build? Boring. Long rod 19, maybe not as exotic as some of the other Frankenstein motors, but I'd bet it would still be a rippin' little motor.

 

I think dyslexicdime said he had one of these and could push it past 9,000rpms.

If this motor could breathe at that speed-look out!

 

This is probably a stupid question, but if the l18 and l20 both have 85mm bores then why does the l20 have more displacement

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The chart gives you an idea how much work you need to get to a certain hp/torque. And that should be the starting point. From there do the math of how much it will cost. This is why a lot of people with the la or sr motor, more bang for the buck.

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L20B rods are longer, yes but that's mostly because the L20B block is 20mm taller than the L18. L16/18 blocks are same height and in that case a longer stroke crank (all other thing being equal, like piston pin height) will have a shorter rod.

 

 

 

L18 stroke 78mm and 1769.5cc displacement.

 

L20B stroke 86mm or 8mm X bore of 85mm that's 45.37 extra displacement per cylinder X 4 = 181 extra cc's.

 

1769 + 181 = 1950cc for the L20B

 

Find the Jason Gray Engine Specs page and start reading. Get a calculator and start running the numbers. There are all kinds of L, Z, KA and VG series parts that can be mix'd n' match'd to make hybrid engines.

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L20B rods are longer, yes but that's mostly because the L20B block is 20mm taller than the L18. L16/18 blocks are same height and in that case a longer stroke crank (all other thing being equal, like piston pin height) will have a shorter rod.

 

 

 

L18 stroke 78mm and 1769.5cc displacement.

 

L20B stroke 86mm or 8mm X bore of 85mm that's 45.37 extra displacement per cylinder X 4 = 181 extra cc's.

 

1769 + 181 = 1950cc for the L20B

 

Find the Jason Gray Engine Specs page and start reading. Get a calculator and start running the numbers. There are all kinds of L, Z, KA and VG series parts that can be mix'd n' match'd to make hybrid engines.

 

I read that last night and again just now. I like that the parts can be mixed and matched, and that there are some pre drawn builds in that thread. My question is whether or not the idea of 280zx flat top pistons in an l20 block with a U67 head, cammed and ported with a 38/38 or side drafts is a legitimate option, or if I should just follow the models of that thread and do something that's been tested. I'm tempted to do my own thing.  If the parts are truly mix n match-able then the motor should do what is expected right? have a compression ratio in the mid 9's, slightly more displacement and breathe better at higher rpm's?

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