Re-build L18 or swap in L20?

[zed]

Goodday everyone

For some time I've been planning to re-build the L18 engine in my Hardbody truck. The engine is standard, and has never been opened - but has high miles now. It's an '89 L18S, V912 head, flat top pistons, with twin barrel Nikki carburettor. The owner's manual gives compression ratio of 9.3:1, and 65 Kw/87hp @ 5500rpm. It's a nice engine - cheap and simple to work on, good torque, and I know it like an old friend! I think I can re-build it myself for about $1500.(including parts, machining)

But ... there are re-built L20B engines available on exchange here for about the same price.

Questions: should I swap in an L20? Would it be an easy swap - are engine mountings, rad, bell-housings the same on L18 and L20? Will the extra 200cc make a difference? Should I stay with the engine I know, or try the L20?

Any opinions would be appreciated.

Zed

[racerx]

There's nothing more satisfying than rebuilding and putting the engine yourself. At the same time, it can also be a headache. If I have the know how, I would rebuild myself since I will have the choice of modyfying the engine. The key is knowing how to. I don't think 200 will make a lot of difference maybe 10 hp. I just installed a stock L18 into my 510 from an L16 and I felt some gain but not that much. I am certain if I changed the cam, bigger carbs and maybe bore it out and bigger pistons, difinetely a lot more, maybe 40 more, header, intake and sidedrafts. The L20 is a good engine so is the L18. May want to check for clearance issue...it boils down to if you trully feel comfortable in rebuilidng it yourself then do it.

 

Good Luck...btw, this is a good time to think about carburation..

[hang_510]

Questions: should I swap in an L20?

Would it be an easy swap - are engine mountings, rad, bell-housings the same on L18 and L20?

Will the extra 200cc make a difference?

Should I stay with the engine I know, or try the L20?

yes

yes - yes, yes, yes (the flywheel is not, 5 bolt vs 6 bolt)

yes

try the L20 (short block)

 

not much mechanical diff, the L20 is ~3/4" taller

the head and carbs will swap too.

[hang_510]

...the oil pan, swap the L18 oil pan too

[banzai510(hainz)]

V912 head on the L20 and maybe put some L18 pistons into that but L20s have a 6bolt cranks and here in the US trucks have a 225mm flywheel while the cars a 200mm so you need to get this solved and figure what you need.

as here I can use the standard 510 clutch in a L16/18 200mm or use the 650KG Roadster clutch.

 

the L20 trucks 225mm use the heavy set up or maybe later Z car 225set up and the T/O bearing.

 

sounds like your L18 is already good. only if worn then go up to the L20 using your L18 head

 

L20 is like 3/4 inch taller and use the mounts already in the vehicle and oil pan/sump set up for the rig u have.

 

 

buy the bottom end and bolt the top half on(of coarse get a new L20timming set)

[datzenmike]

Find an L20B and re-build it. If you get a re-build, it will have dished pistons already in it so you won't want to tear them out and put the flat tops in. It comes down to L18 vs. L20B. L20B wins. It already makes as much or more than the L18 with pistons and head. L20Bs have more displacement (power) and more stroke (torque). There should be plenty of room in a Hardbody for an extra 2cm of engine height. On the plus side you still get to re-build a motor, just a bigger one.

 

BTW :

 

L20B with closed chamber head and flat tops.... 10.68 cr

Above with stock pistons ............................. 8.91 cr

[zed]

Thanks for all the good ideas guys

zed