Here here,
One very respected professional race engine builder here said the U20 was
the most efficiently designed 8 valve production car head he had seen.
That's why even an Elise has problems staying with me. on acceleration
Show some Z guys a U20 head and they drool - I have seen them do the
slobber thing (the reason - it's better than the FIA Z head - as Gordon
shows below)
But even slugs like pushrod MGB engines can be made to go. ($15,000 US
later they are quite fast)
Regards,
Howard
-----Original Message-----
From: Gordon Glasgow [SMTP:glasgow@serv.net]
Sent: Saturday, 13 May 2000 1:05
To: datsun-roadsters@autox.team.net
Subject: Re: U-16 Race Engines?
I think the only thing "cobbled" about the U20 head design is the fact that
they kept the R16 chain
to the jackshaft and added the 2nd chain. The port design and flow rates
are actually pretty
spectacular. Yeah, they're both non-crossflow heads, but so were lots of
engines.
R16 valve diameters are 42mm intake and 32mm exhaust
U20 valve diameters are 46mm intake and 36mm exhaust
(Just for a good giggle, compare that to the "monster" FIA head for the
L-series engine - 45mm
intake and 35mm exhaust)
So here's what changed between the R16 and U20:
25% increase in displacement
20% increase in intake valve area
27% increase in exhaust valve area
40% increase in power with SU's
56% increase in power with Solexes.
Looks to me like the U20 head is the superior design. A friend of mine who
does nothing but cylinder
head work says the U20 is the best flowing non-crossflow head he's ever
tested.
HIGHKIX4@aol.com wrote:
> With all due respect to the U-20, it is a
> sort of cobbled together OHC design,
> same flow pattern as the pushrod motor...
> putting the U-20 crank in the 1600 to
> make a pushrod 2L is a better idea,
> I think......of course I am somewhat
> biased....
> Best Regards
> Jim
> Chesapeake Va
> 67 pushrod 2L 5spd
> 72 510 wagon
--
Gordon Glasgow
http://www.gordon-glasgow.org
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