Not trying to start a flame war here, and I admit the L-series is a good
design, but...
Given equal build specs, an L-18 will not make more power than a U-20. The
big difference is in the head and valves. The stock U-20 valves are actually
larger than the valves in the infamous FIA heads for the L-series engines.
Even if you put a U-67 head off an L20B on an L-18, it won't flow like a
U-20 head.
Intake Exhaust
------- -------
L18 SSS head 42mm 35mm (same as L20B U-67)
Early FIA 45mm 35mm
Late FIA 44mm 36mm
U-20 46mm 36mm
The guy that does my head work told me the U-20 was the best-flowing
non-crossflow head he had ever seen. In fact, he had a Jensen-Healey
twin-cam head in his shop at the time, and the U-20 was just slightly below
it in flow rate all through the range.
Everything else in a race motor can be equalized, and the cost equalizes
along with it. You don't run stock pistons and rods in a race motor. So
custom pistons cost the same regardless of whether they are L-series or
U-20. Same with Carillo or Pauter rods. And machine work is machine work.
The main cost difference is in the timing chains, gears and tensioners. But
if you're building a $10-15K race motor, that's minor.
Gordon Glasgow
Renton, WA
> -----Original Message-----
> From: owner-datsun-roadsters@autox.team.net
> [mailto:owner-datsun-roadsters@autox.team.net]On Behalf Of Victor Laury
> Sent: Monday, January 23, 2006 4:41 PM
> To: jtorres67; datsun-roadsters@autox.team.net
> Subject: Re: L series engines
>
> An L18 is a high performance motor that can easily be developed
> to exceed any race built U-20.
>
> Victor
> Downtown Los Angeles
> 70 SRL
> 70 521
> 71 521
> 72 240Z
> http://www.fotki.com/datsunvic/
|