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| Re: L-series engines and math (long) |
Subject: Re: L-series engines and math (long)
by shit192121 on 2002/1/13 10:15:00
My responses follow Andrew's comments.
L20 crank journals can be ground down - most people wouldn't bother because you just start with a L20 block anyway - heaps cheaper. it used to be a VERY common trick in Class N rallying in
South East Australia (capacity restrictions and all that).
I figured that was how those guys were making their 2 liter L-18 motors. Seems like the rod to stroke ratio would suck and these motors would wear the cylinder walls more.
Strangely with a 5mm overbore your stroke to bore ratio comes out pretty good....
It was "pretty good" to begin with. The L-16 or L-18 motor is already "over-square" (likes high rpm's) so it's stroke to bore characteristics don't really change, you just have a bigger motor
that may like to rev even more.
Even using the 88mm pistons brings you out near to 2250cc using a stock 20b crank,
W/ 88mm pistons and a 86mm crank I get 2092cc, look here for some info on a long rod L-21b: http://home.att.net/~jason510/longrod21.htm
let alone one with increased stroke (hey - if you're regrinding the base circle of the crank anyway!!).
Why not just use a Z22 crank? Unless you want the fully counterweighted L20-b crank.
L18's were a stroke job only of L16's so using an L18 crank in an L16 gave L18 not L17.... At least that's the way it was with Australian models.
Ozzie models my arse You guys must be using L-18 (larger bore) pistons or something.
Here's a easy math trick for 4-cylinders:
Square the dia. of the bore (in cm.) X pi X the stroke (in cm.) and you get the volume in cc.
Using the dia. as opposed to the radius of the bore gives you the 4 (after the dia. is squared) for the 4 cylinders. You can then multiple by 1.5 if you're dealing with a 6 cylinder. No more
dividing that bore in half.
L-16
8.3cm (bore) squared X pi X 7.37cm (stroke)= 1594cc
L-17 (L-16 bore w/ L-18 crank)
8.3cm (bore) squared X pi X 7.8cm (stroke)= 1687cc which rounds up to 1700cc or and L-17.
Don't make me argue that again, too much math talk:)
As far as U20's being the basis for L24 engines, that's to do with the whole development from Roadster to the Z which replaced it.
The Nissan L-series engine was a copy of Mercedes' early 60's OHC design. Mercedes timing chains work on an L-series motor.
Note that the L series never ran anything like those carbs until the Z came out, but twin Su's and Solex's were used on the 2000 roadster.
Wait, Both the z-car and 510 got SU carbs like on the roadster. The 610 had EFI on an L-16 or L-18. And Nismo sold the same Solex set-ups for the z and 510.
I know there were L20 and L23 motors around at a similar time
Actually the Z had been in production 5 years before the L20-b came out (1975). And Nissan never made a L23, L24 and Z22 yes, but not L-23. That motor is a "hybrid"; Z20 block, 6" rod, 89-
90mm bore, Z22 (92.0mm) crank.
- check the carburetion and cam profiles compared to the Z....no similarity at all.
Again, yes on the SU's and the 4-cyl. even got efi like the later Z's. And I believe the specs on the 4 cyl. SSS (or L-20b) cam are much like the Z's. What was the point you were trying to
make about the Z motors?
DOHC models not seen elsewhere - such as the 432R DOHC S20 engine, with triple 42DCOE webers (from the standard 2 litre triple solexes).
Ther were also TWO versions of this head for 4-cylinders. One made by Nissan and One by OS Giken, there's a picture on the Datsun Soul Website and in the U.S. "Datsun... Modify" books.
Did america get the 3 seat roadster?
Yeah, I think up until 1966 when they switched to the R16 motor.
Cheers,
Daniel
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