My L20 Stroker Ideas... Any Advice?

[Bamadawg]

Good day all, new member here - thanks for providing this forum!

 

My current '82 720 w/Z22S 5spd is getting VERY tired... that ole smog head is the pits and a VW Beetle can pull hills better than me!!!

 

So, it is time for a motor update. I know I could use my current Z22 and add the U67 head for better performance, but I have access to a '75 and '76 L20B truck motor and a L-series 4spd. tranny for a swap. I had rather do the build offline, then jus swap the L20 in - which gives me the Z block for a later build.

 

I have been feverishly reading different Datsun forums, from Roadster, 1200, 510, 610, 620, 720, Zcar - the gamut... trying to figure out a good spec for a L20 truck motor. I want solid pull from stop through mid-range, and be able to cruise @ 65mph with a lil left for a kick when I need it for hills - the basic daily-driver with a smoothe torque-curve - no high rev stroker like the 510 guys love (not knocking 510 guys, they build some awesome rides!).

 

What I am thinking:

L20B block +2mm (.080 over) - Z22 crank - L20 rods - Z22s pistons - U67 open head. Should be around 9:5:1 CR.

 

On the head, leave stock valve sizes using new SS valves - clean up the casting around the valves for better flow - stock intake/exhaust port sizes.

 

Use something like a Weber 32/36 DGEV or 38 DGES/DGAS downdraft on a L16 stock manifold. Finding a stock shorty-style header. Add electronic ignition.

 

Have the L 4spd. from the '75 looked over and install it. Look at changing rear gears at some point.

 

Any advice on this set-up?

 

Thanks...

Nate

[hang_510]

thats how i started, and then...

ended up improving on Z block instead...no replacement for displacement :D

 

id go basic on the L20 and while its still on the road!!! do an LZ22 with all the improvements there :cool:

[kiznook]

hmm...

 

quick response- find a 5speed. don't intentionally swap IN a 4 speed.

[lynchfourtwenty]

its partialy for his son to drive also, and i already talked him out of a automatic on the nwde site.. he wants something easy to drive with good gearing.. the older zx 5 speeds make the lil l20b's sluggish from what i've heard.. so if u use a 5 speed may want one from an older z.. like a 77 or something like that..

 

BY THE WAY ... Welcome man, glad ya made it here

[Bleach]

or go with a 2.4L

Maybe a Hardbody KA24e engine. No fab work needed on the engine and its fuel injected. :D

[Bamadawg]

Thanks for the replies... I understand the close-ratio gear boxes are better for torque... so maybe I can look for the earlier Z speed box.

 

Yea, I think the Z block has better potential, so when I get it out... I can plan a new project around it. The K block is very tempting... I think the dewd that has the 2 L20B's may have a hardbody also... I will check it out and see.

 

Nate

[kiznook]

you should be able to bolt a KA up to your existing tranny too if I'm not mistaken

[ssfwgn]

The 22s uses the same rods as the l20b. I dont think it worth doing all that work to a L20b. It would cost you a bit more to do that versus rebuilding your 22s and just putting a U67 head on it.

[lynchfourtwenty]

just go over and over and over everything until u decide what u want

theres always pro's and cons...... AND SOME OF US JUST LIKE OUR L MOTORS.. kinda sad that i've beatin a hardbody.. well maybe the person was an idiot.. maybe didnt try hard enough.. either way i was GOOOOOONNEEEE saw him in the rearview at top of 2nd

[Bleach]

you beat him cuz he had a Z24! ;)

[lynchfourtwenty]

DUDE YOUR RIGHT!!!!!!!!!!!! SHIT I NEVER THOUGHT ABOUT THAT... i was like HAHAHAH I BEAT THAT DUDE .. now i know why.. either way.. i won so HA! :cool: ;) :P

[datzenmike]

Any advice on this set-up?

 

Thanks...

Nate

 

Well: With 97mm X 86mm bore and stroke, - 2.67cc deck height, 9.32cc dish Z22 pistons, and 45.2cc open chamber head I get 9.92:1 compression and a 2044cc motor.

 

The stock Z22 (117 ft lbs @ 1,800 RPM) would out torque the stock L20B (108 ft lbs @3,600 RPM) by about 10 ft lbs at half the RPMs. (no need to go to lower rear end) The Z22 and Z24 were stump pullers (at lower RPMs) An L head would improve the torque/HP but move it higher up the range. There is more performance stuff available for the L head.

 

The Z24 makes 135 ft lbs at 2,800 RPMs

[Bamadawg]

Now the temptation is there to just use my Z22 and do the 2.3L big bore - I wonder what the est hp/torque would be?

 

Parts: Z22 crank, KA24 pistons, Z22S/ L20B rods in a +2mm bored Z22 block or +4mm Z20/L20B block.

s/2+r+p= 92/2+145.9+34.0= 225.9 mm

piston deck height: -1.55mm below deck

 

What would be a good intake/carb setup for daily driver on the 2.3L big bore? Would like to find a shorty header and use 2" exhaust I would guess.

 

Nate

[datzenmike]

One of the guys on The Realm built up an LZ22 with side draft carbs and dyno'd it. He got a solid 120 plus rear wheel HP. That's REAR WHEEL HP so probably 150 in the real world. When I get home I'll try to find the graph.

[banzai510(hainz)]

Byron510 on the realm claimed 130 rwhp. on a just bolted together LZ motor.

But i find out he has 4.44 Gear ratio which cheats it a little bit.Shows more torq.

Most Dyno pulls are in 3rd gear right?

 

Yellowcar (TIM)has a LZ24 I think is going to sell. Its all done and has a dyno sheet. Contact him on the realm also or maybe here

[Bamadawg]

I am just a little puzzled about the best carburetion system to use... I see a good bit of 620/720 owner set-ups that are using SSS intakes with dual 240Z SU's - which I think are 46mm, tho I have read about some 44mm SU's on certain older models - then there are the 38mm SU's used on the 1200GX and other Datsuns. From what I gather from reading, and some advice from Hainz... the SU's function better at high RPM, and the Weber downdraft is better for low/mid RPM, like a 32/36 DGEV... then for a bit more throttle response, you can use a 38 DGES/DGAS - and just watch for heavy-feet for proper MPG - akin to using a 2bbl vs a 4bbl on a V8 - better overall MPG with a 2bbl - better throttle response with the 4bbl.

 

If doing a downdraft... whats a good manifold to use on the U67 head? Stock type L20... or maybe a aftermarket (Offenhauser?) - perhaps they offer longer runner length?

 

Cheers...

Nate

[banzai510(hainz)]

offenhauser are overrated!!!!!!

Just port them out and blend the edges out.

 

as for the 38DGES double opener you got to learn to work the Clutch just right at take off cause it can BOG if the RPMs are not up just a little.

But I like this carb very much but Expensive NEW.

 

For all out HP/Fast the Mikuni/weber Dcoe are the ones to get.

 

I have been in a L20 510 with SUs and I was impressed. It seemed to pull harder then my L16 with Mikunis. But this was just around the neiborhood(I couldnt give it the top end test.

 

If you want alot of torq Ill let you talk to datzenMike as if your doing a 4x4 he is more a expert on these matters. I have to say My pumped L16 with dual 40s has no torq at Low rpm and a Honda Minivan out pulled me the other day!!!!!!!!

[hang_510]

Now the temptation is there to just use my Z22 and do the 2.3L big bore - I wonder what the est hp/torque would be?

 

yes. im starting with dual 40 mikunis (have 45 weberss in case there too small) and using a set of forged pistons (vs the stock KA) -close enough. lotsa U67 head work.

dreaming of 150 at the wheels :eek:

[ssfwgn]

The LZ23 has alot of potential. I'm running 22 crank 22E rods and KA pistons. W53 head with stock valves, dual 44mm mikunis and a stock exhaust manifold that