Have a look at this Gemini build 'em up (355Hp at the rear wheels):
http://www.autospeed.com.au/A_0599/P_1/article.html
Interesting to see he used a Delco computer system...I have one of those in
my Pulsar...you could probably pick them up cheap?
----- Original Message -----
From: cam <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Sunday, February 25, 2001 12:33 AM
Subject: Re: L20B TURBO v SR20DET
> Just to add my two bobs worth...
>
> Years ago (about ten) I went down the path of turbo charging L series
> engines. I did it pretty much by trial and error (lots), keeping in mind
> the last ten years in turbo charging development has been huge.
> Without going through all the failures, I ended up with the following
combo:
> a) L20 Block bored, honed, O Ringed and Decked 4mm O/S.
> b) Group A Skyline pistons and rings (don't ask me what model, don't
> remember, but Datrally told me they were pressure cast not forged.
> These pistons gave me a 5mm lower pin height and therefore lower
compression
> approx 6.5:1)
> c) Nismo head gasket (from Datrally cost $$$)
> d) Factory bearings (Datrally said good for at least 300hp)
> e) Crank linished (I'm yet to see a stuft Lseries crank)
> f) Modified Bosch L Jetronic mechanical fuel injection (off an early
> model Volvo !!, I had small injector mounting blocks tig welded to a
single
> Weber inlet manifold)
> g) IHI RHB6 Turbo on a shitty old cast iron manifold and 2.5" exhaust
> (Second hand don't know specs of trim and comp wheel etc)
> h) 'Turbo grind' cam (Just got called Datrally, who knows what they
gave
> me!)
> i) Re-Curved electronic dizzy
> j) Mazda RX2 Crossflow radiator and front mount oil cooler.
>
> This engine was NOT intercooled (Yes it should have been).
>
> At 17psi in produced 165Kw at the wheels (should still have dyno sheet
> somewhere, dunno what that is in horsepower at the Flywheel) To give you
an
> idea of 'on road performance' this engine with 5spd and 3.7 diff in a
1600,
> would light the tyres coming out of a slow 2nd gear corner.
>
> The exhaust manifold glowed bright red when running on the Dyno and I
> suspect turbo charger was two small and working to hard and becoming
> restrictive at these boost levels.
>
> I am confident that with a custom stainless manifold, TO3 turbo(or
similar),
> good Intercooler and EFI this engine would be literally a ball tearer and
> 25psi wouldn't be out of the question.
>
> BUT
>
> What I'm currently doing is exactly what the question was initially
> about...putting an SR20DET into the 1600. I ultimately sold the old turbo
> engine and went back to a twin Weber n/a engine after heaps of reliability
> problems and the 'all or nothing' characteristics of the turbo engine
> (super low compression / high boost).
> This time around I had the choice of the factory developed, tried and
tested
> SR20DET. No doubt when it's up and running it will run like a charm,
start
> in an instant, provide smooth linear power and be reliable and drivable
day
> in and out.
>
> I suppose what I'm trying to say is, that if you wanted to prove a point
> about how much power you could get out of the L20, you could. It will
make
> stacks of power and the L Series is strong and will handle it (just like
the
> FJ20).
>
> If you want smooth, reliable and drivable power the only answer is the
SR20.
>
> Feel free to email me with any questions,
>
> Cam.
>
>
>
>
>
>
>
> ----- Original Message -----
> From: "Tom Richardson" <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Sent: Sunday, February 25, 2001 12:06 AM
> Subject: RE: L20B TURBO v SR20DET
>
>
> > Warning: long
> >
> > Denzil,
> >
> > I recently had a debate with a V8 knucklehead (and 2V fan) over the 2
vpc
> vs
> > 4 vpc subject in an engine with forced induction. I don't claim that
this
> > is correct but it makes sense to me :)
> >
> > Assume you have two completely identical engines, one with 4 vpc and one
> > with 2vpc. This is obviously not a realistic comparison given that the
> 4vpc
> > cylinder head would undoubtedly feature twin camshafts and a superior
> > design, but bear with me
> >
> > With a 4 vpc engine, there is a distinct disadvantage at low rpm.
Because
> > the gross opening into the cylinder is larger, the velocity of the air
> > through the ports is lower and the result is poor cylinder filling and
> > consquently poor low rpm torque. This one of Bernoulli's thereoms. If
> you
> > don't believe me, some manufacturers (Toyota) overcame this problem on
> early
> > 4 vpc heads by artificially restricting the flow of the intake air at
low
> > rpm with a butterfly valve, hence increasing air velocity.
> >
> > If you replaced the 4vpc cylinder head with a 2 vpc cylinder head, the
> gross
> > opening into the cylinder is smaller, hence air velocity is higher.
This
> > results in better cylinder filling at low rpm, and strong low rpm
torque.
> > At higher rpm, the superior flow characteristics of the 4 vpc head will
> > result in much improved cylinder filling hence better torque (and since
> this
> > happens at high rpm, better power)
> >
> > Looking ok for 2 vpc designs so far, one point to each corner
> >
> > However when a turbocharger (assume identical turbochargers for both
> > designs) is added into the equation, the lower restriction placed on the
> > inlet air by the better flowing 4 vpc head will result in improved
> > turbocharger efficiency, and this means lower air temperatures, hence
> higher
> > density, hence increased pressure (boost) This is the ideal gas law,
> PV=nRT
> >
> > So the 4vpc motor will outperform the 2 vpc motor at low rpm and high
rpm
> > (due to the same effect- higher compressor efficiency) provided that
both
> > turbos are producing boost.
> >
> > This isn't to say that its impossible to build a 350hp turbocharged
L20b-
> it
> > has been done!
> >
> > I think revability would be better with the SR20DET because of the
> > improvements in metallurgy since 1968, but that's not to say it's hard
to
> > build an L20b capable of reving to 8000rpm+. One thing you could do to
> > improve revability would be to fit longer rods (ie Z20E) This results
in
> > smaller frictional forces in the bores, so less hindrance to high rpm.
> >
> > The counterflow head would be a disadvantage, but there are plenty of
big
> > power outputs from these designs around.
> >
> > I should think that if you are aiming for 300+ hp at the flywheel, this
> > means you will either be running crazy revs or crazy boost (or both!),
> talk
> > to a local machine shop about shotpeening nitriding etc for the power
> you're
> > aiming for. Forged pistons would be a must.
> >
> > Remember that a full house (ie race) N/A L20b will pull 210hp+, so 300hp
> is
> > a reasonable target (IMHO)
> >
> > Also, there is a Z18 here in a 510 circuit racer which pulls 327hp with
> > stock rods, crankshaft, and valves. It uses 125lb valve springs and a
> > George Fury spec camshaft, extensive cylinder head and intake manifold
> work
> > with a Garret T04 on a custom manifold pushing 17psi. This is
essentially
> > the same design as the L series blocks but with a (rather poor)
crossflow
> > head - and this is with a 180cc capacity and 8mm stroke disadvantage!
> > Nissan L blocks are TOUGH. Let us know how you go with your project!
> >
> > - Tom
> >
> > PS It'll be fun to tell the losers that you've just got a L20b ;)
> >
> > -----Original Message-----
> > From: [EMAIL PROTECTED]
> > [mailto:[EMAIL PROTECTED]]On Behalf Of Denzil Palmer
> > Sent: Saturday, 24 February 2001 7:48 PM
> > To: [EMAIL PROTECTED]; [EMAIL PROTECTED]
> > Subject: L20B TURBO v SR20DET
> >
> >
> > Looking at options for my next project, a turbo engine is a must to beat
> the
> > local boys in their WRX's etc. The Hot 4's 2001 yearbook has the NIS-016
> 510
> > that does 11.4 @ 120 mph with the SR20DET, and it looks pretty innocuous
> (ie
> > totally stock except for the wheels and stance) from the outside. It has
> 260
> > rwhp at 18psi, which indicates 335 engine hp assuming 22% drivetrain
loss.
> > Diff is a billet axle 3.9:1 R200 LSD with 225/50-15 tyres.
> >
> > The question is, given a similar size turbo would the L20B engine be
able
> to
> > produce as much power as the SR20DET? Take it that the L20B would be
> > injected, with after-market computer, intercooled, mandrel exhaust and
> built
> > to the required standard. The fact that the modern engine would be
cheaper
> > isn't the point. The idea is to keep the traditional L-series engine but
> > with a modern induction system.
> >
> > Breathing (ie 2 valve vs. 4 valve) wouldn't be an issue would it, as the
> > turbo force-feeds the cylinders anyway. What about rev-ability and
maximum
> > attainable revs, is the L20B too long a stroke and too slow to rev? Is
the
> > non-crossflow head a disadvantage?
> >
> > If the 300+hp L20 B turbo idea is feasible, then what needs to be done
> > w.r.t. engine internals? If anyone has already done this your thoughts
> would
> > be invaluable.
> >
> > Thanks
> >
> > Denzil Palmer
> > Queenstown
> > New Zealand
> >
> >
>
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