Re: More Spica stuff

[bearbvd@domain.elided (Greg Hermann)]

At 8:44 AM 11/14/99, Steve Schaeffer wrote:
>>The idea of using one "high-performance" profiled cam to cover a multitude
>>of possible engine tuning situations therefore seems to be pretty
>>incredible to me!
>
>Who said he had just one profiled cam?  Wes is the type of person to spend
>the time it takes to design cams for various applications.  It is certainly
>no mean feat to do that, and make the car pass emissions.

Well--somebody was talking about just bending the spring, not re-profiling
the cam. Point is that ANY slight deviation from the specs for which the
cam is ground will cause a problem. A couple of degrees of cam timing, or a
couple of thou of valve lash is enough to throw things off. Not exactly the
sort of stuff the average racer--or hipo street driver is equipped to deal
with!
>
>>Another thing to pay serious attention to-- in order to equalize fuel
>>delivery to the cylinders--is having equal length high pressure fuel tubes!
>
>I thought they already had equal length tubes!

Been so long since I've looked at one, I wouldn't remember. Just threw out
the poin, it is certainly critically important. Been there, fought with
that on enormous diesels much more recently.
>
>>Best one could really hope for would be to be somewhat too rich--and in
>varying
>>amounts-- throughout the power band.
>
>I really don't think so, Wes wouldn't settle for that.  He uses his
>Dynograph LED richness indicators to help straighten all that out.
>
I'm not familiar with the Dynograph unit--but unless it is a true WBO2
unit, like a Horiba (not saying that the cost of a Horiba) is necessary),
the results are open to a LOT of question.

>>How bout using (easily available) a linear actuator (with position
>>feedback, preferably) to position the rack in the Spica pump--and
>>controlling said actuator with a modern ecu brain...
>
>Yow, sounds very initimidating.  Actually Wes is selling and configuring
>Electromotive's EFI as well.

I will not give an opinion of the Electromotive units on list. If your
conclusion is that this speaks louder than words, congratulations,
Sherlock!

A properly done and controlled electromechanical linear actuator for the
SPICA fuel quantity rack could turn out to be a _VERY_ good approach!
Really--it's a much simpler design problem that a typical modern efi unit,
and could have some substantial performance advantages over electromagnetic
injectors.

 He did a Maser V6 twin turbo with it, and it
>is the way of the future for hot rods.  He controls all aspects of the fuel
>and ignition curve with a laptop.  I certainly don't think you could adapt
>Spica for that, however.

Really rather easily! And tuning from a laptop--AND datalogging--IS a
pretty desireable way to go!!

But--for anyone considering buying an aftermarket efi unit, I would suggest
a taking a VERY hard look at Fel Pro, the (not quite yet on the market) NEW
Accel/DFI unit, Autronics, MoTec, and EFI Systems LONG before considering
an Electromotive. And if you do not understand the technical significance
of all of the published technical specs for each of the units, ask someone
who does before you buy!

Also, it is really well within the realm of feasible--for someone with the
appropriate skill set--to reprogram the ecu from a '88--'95 Chevy TBI
pick-up to control the SPICA pump in the manner described. If one were
doing it this way--the entire ecu, wiring harness, and sensors could likely
be obtained from a bone-yard for $150 or so! The linear actuator and
adapter for the SPICA pump would be in addition to this cost. No
snickering, please. The GM ecu's are well proven, extremely reliable in a
typical automotive environment, their code has been fully disassembled, and
they are cheap. What more could you want??
>
>Obviously I'm a fan of Wes, he's the person I go to for all of Turner's
>problems, and I'm just completely satisfied with his values and abilities.
>He's been working with fuel injection and complete race car prep since the
>mid-60's, but will listen to anyone's ideas and gi

My comments are no way intended to be critical of Wes. Just presenting the
cold, hard technical facts of the matter here, based on technical
experience every bit as lengthy as Wes'.

Regards, Greg


>Steve S.
>Seattle, WA
>NWARC

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