Howard said:
>One meaning of "imagining" is perceiving something fictional and I agree
>with that.
>
>A ported U20 with the mods described and some valve machining can go to
>170bhp and more, I have one with similar mods that has been dynoed at a
>little over 170 but the compression is actually lower than std (9.2 to 1)
>(my Silver car).
>
>The mods on my race U20 are a little more exotic and mine pulls 228bhp (so
>says the dyno). (normally aspirated with 11.8 to 1 compression). (My Blue
>and white race car on Gordon's site).
>
>I agree on the parts bit. I have used modified L series titanium valve
>retainers on the U20.
>
>The design efficiency of the U20 is far greater, take the Heads side by
>side and look at the huge ports on the U20 compared with the L series.
Josh said:
>It seems I will have to continue as devils advocate
>for swaps.
>From what I gather there isnt much more that you can
>do to a U20 beyond going solexs, header and a cam.
>Which is great power! But thats only putting out
>around 150hp, after some porting I couldnt imagine it
>going up much more from there.
>An L20b can get 170hp with the same efforts. I have
>not made the swap nor have I driven any Roadsters with
>the swap but I can tell you the L20b in a 510 screams
>and pulls hard! Its also about the easiest engine on
>the planet to get parts for (aftermarket or stock).
>I would imagine Ronnie Day could tell you more about
>the pluses and minuses of the L.
I still say probably the best option in this situation is a KA-24, if
you're going to do a swap. I don't know if I would or not. A whole lot
depends on what kind of shape your current motor/trans are in. As for
getting L-bits and 5-speeds cheap, maybe so, maybe not. The L-20b's are
still relatively common and probably put in more mainland US cars than
the L-16, certainly the L-18. I agree with Howard that you can probably
get a properly setup U-20 to generate as much max power as a comparably
tweaked L-20b, but I'm not sure either of them would be well suited for
daily street use, and I think that's were you're headed?
I thought we'd been through this here, I know we have on the 510 list,
but in the daily driven on the street world there really isn't a
substitute for cubic inches. That's why the KA-24, VG-30, and L-20b's or
LZ-20's turned into L-22's are so popular in 510's, particularly the
later option. Take an L-20b, bore it to 87mm, drop in LZ-22 pistons,
rods, and crank, and boom, major torque. Very useful on the street. And
the extra cubes can be free or close to it. Some prefer to start with the
LZ-20, but (at least here) they're far less common than the L-20b and
LZ-22/24.
Obvious question is why not build an L-24 (four cylinder version) using
an LZ-24. You can, but it's a LOT more work. Unless you have custom rods
($$$) and or pistons (more $$$) made, you'd have to use an LZ-24 block
which is 3/4 taller than the L-20b which is itself 3/4 taller than the
L-16/18. You'd also need to fabricate a 3/4 taller L-type front cover,
and finally (my personal favorite) you'd have to cobble up a timing chain
as none long enough are (known to be) available. If you use the LZ-24
crank in the L-20b block you'd have to clearance the pan rails and maybe
the bottom of the bores, too, plus you'd have to have custom (short)
rods, AFAIK.
If you go with the KA, you have both the additional displacement and the
late model functionality of fuel injection. You guys gotta see Bill
Kenyon's car. Very nice. However you go, don't expect it to be easy,
quick, or cheap to do a swap. I really believe that for a street L-22 is
the rare combination that is inexpensive and yields impressive gains for
the little money spent. If I remember correctly, Gordon built a similar
motor a couple of years ago before he sold his 510. I definitely will be
building one this next year for the '73, after the E/P car is going.
________________
Ronnie Day
rday@home.com
Dallas/Ft. Worth
'71 510 2-dr (Prepared class autocrosser)
'73 510 2-dr (Street Toy)
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