[DML] Re: Delorean Turbo

["therealdmcvegas" <dmcvegas@xxxxxxxxx>]

I's a good question. Why hasn't anyone picked up on the design? Could
be because of royalties, time involved in configuring (minimal as
you'll see), or something else?

U.S. Patent #: 4,336,688
Bias Boost Control System

In a nutshell, Legend designed a Variable Boost system of sorts by
utilizing the wastegates, rather than Variable Geometry adjustable
vanes or secondary turbos like you see on most engines.

Turbo lag slows down a car off the line, because you need to spool
those turbo chargers up to build compression in the combustion
chambers. High Compression turbos spool quickly, and are usually not
suited for an engine's entire power-band. They'll deliver too much
boost at higher RPMs, and can cause pre-detonation, engine damage,
etc. Because after all, as engine RPM's increase, so does the boost
pressure.

How to fix: There's a number of ways to avoid engine damage, but
unfortunately, you have to sacrifice bottom-end performance to
stabilize the top-end.
->Reduce Compression (reduces fuel burn efficiency, and further
hinders spool-up)
->Install 2nd turbo charger with different geometry/lower compression
to feed engine when primary turbo is bypassed (EXPENSIVE and
complicated, plus adds weight takes up space in engine compartment)
->Use a Variable Geometry Turbo (Rotating vanes coke up way to easily,
although stationary vanes that slide rather than rotate are
self-cleaning. But only hit the market for diesel trucks within the
past few years)

Now, here's your final option, and that is Bias Boost Control. By
measuring the gas pressures inside the Intake and Exhaust manifolds,
you can trigger the wastegates to slowly open as the RPMs increase,
and thus slowly reduce boost pressure as RPMs increase as well and
avoid engine damage. Plus with an EGR valve, it can reduce engine
knock, and help prematurely raise the Intake manifold's pressure when
it falls below that of the exhaust manifold, thus reducing spool-up
times even further. Problem solved.

Bonus:

1. As you get to those higher cruising speeds, boost is reduced, and
fuel consumption decreases. But, since it's constantly monitoring both
manifold pressures, it can also quickly close that wastegate to give a
sudden boost in in case you suddenly need some passing power at high
speeds, and of course it decreases back down too. Plus with a constant
feedback from the engine's pressures, you could probably avoid engine
detonation without any knock sensors.

2. Since the turbos let off and balance out as the manifold pressures
stabilize, less fuel is of course consumed. So we get not only
improved gas mileage, but better emissions (lower HCs, and NOX).

It's a purely mechanical system, with quick adaptation to electronic
controls if nessisary. Plus since it bolts right on, yet maintains
it's own control systems that need not intergrate into existing engine
controls, it was perfect for the DeLorean. Both from the car's
drivetrain standpoint, as well as how simply it could have been bolted
onto crate engines, and thus cars with no major upsets to the
production lines at the factory.


So now, here's your answer:

Why haven't any other production cars used this design? On that, your
guess is as good as mine. Politics? Royalty costs? After all, this
isn't just like a turbo charger concept, or even a variable geometry
concept which cover just one component. It's an entire control system
that's patented, and wouldn't work without every covered
component/theory involved. And as you can see, that patent coveres
quite a few things.

Why are there no ready-made kits for the DeLorean? Probably a little
of the above, and the fact that there are certain variables that are
unknown. There are reducing valves, and spring-loaded valves that
connect the wastegate actuator up to the Intake and Exhaust manifolds.
And what those values are, I have no idea. Now I'm sure that over the
years there have been a few people within the marquee that have known
how this system works. But up until I found that layout on the U.S.
Patent Offices website, it was a mystery to me. So perhaps lack of
knowlege could have been another reason as well.

Later on down the road in a few years, I plan on trying to duplicate
this set up on my car. I've already got 2 IHI RHB-5's with
water-cooled ports on 'em ready to go. I've just got to figure out
what the values for those ports are...

-Robert
vin 6585 "X"



--- In dmcnews@xxxxxxxxxxxxxxx, "ronkhanna" <ron.k@...> wrote:
>
> 
> Hello All,
> 
> I happened to come across an old Road and Track Article on Tamir's site 
> regarding Legend Industrie's development of a turbo version of the 
> Delorean.  In that article, the author mentioned he was able to test-
> drive the prototype.  I'm curious to know why there is no aftermarket 
> turbo version based on the successful work of Legend Industries. Any 
> ideas?
> 
> Oh, and it's my first post, so please be gentle. ;)
> 
> Cheers,
> 
> Ron K.
> Oakville, ON
>




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