Bolt on Throttlebody suggestions/Air cooled EFI

[Ron Schroeder]

At 11:09 PM 9/25/01 -0400, you wrote:
>Ron writes:
>
>> Fancy meeting you here ;)
>
>Small world! Should have figured you were playing in this area as well!

>You are braver than I am. If I could get $15-25 manifolds I'd be welding
>now. But at $200 for a used pair I am not ready to take that step. Besides,
>they are angled. I'm curious, I have not even looked. Are our manifolds
>Aluminum or Cast Iron?

Aluminum

>I'm thinking fabricate some flanges, and use DOM tubing for the runners. I
>have found some weld on bosses for EFI I could use, and the CIS injectors
>could be even easier with the injector inserts mentioned by others.

For testing, you could make it from PVC drain pipe.

>> I am using a home brew ECU that at least works better than carbs but I
>want to go with a re-maped 727.
>
>Is this the best ECU to work with? I need cheap, well understood, and
>capable of being FI only. (No ignition yet)

I am nowhere near an expert on that but the 727/730 seems well documented
and was used in both TBI and PFI and with or without ignition.  I am sure
the experts on the list could give more info or suggest something better.

>> Why do you want to use a mechanical injection on the Pinz?
>
>Good question. Simplicity and availability of cheap donors is the biggest
>reason. Also the fact that they can be dialed in better than a carb, but not
>have to run at 14.7.

You can do that with open loop on EFI too.
 
>Regarding the tuning range range of CIS, there are enough different airflow
>sensor/distributor curves available on the cheap that I'm hoping it's not
>going to be that complicated. It also helps that the pinz has a 4500
>redline. A VW van setup might be a reasonable match for the curve of the
>flow rate. (Hard to explain, the curve of the air sensor plenum controls the
>air/fuel curve shape. Pressure controlls the steepness of the curve, and
>rising rate regulators can influence that even more. The mixture setting
>sets the baseline. OK, so it's not a map, but you can do a certain amount of
>"programming" of the mixture. Just without the use of electrons!

That is what worries me.  The "Map" can be moved up or down by adjusting
the pressure but changing the shape of the "Map" requires changing the
shape of the venturi.

>Also, later K-jet distributors had modifications to reduce the inertia
>effect with bumps.

But that doesn't help with pitching movement.


>Initially, I'm thinking two  simple plenums about 2" tall on the factory
>manifolds with the CIS injectors mounted on top shooting down into the
>manifold mouths. Sort of a CIS TBI approach! Since the injector nozzle will
>almost be in the runner, I should be able to avoid differences in mixture
>due to venturi effects from the airflow into the plenum being off center. A
>single two stage throttle body between the two plenums and I should be in
>business.

Two stage or two barrel?

>> Do you really think that it needs to be richer than 14.7 or just make sure
>> it never goes lean?
>
>Well, the pinz manual sez to tune the carbs for 2-5% CO. The bug guys have
>had lot's of problems with 14.7 EFI's offroad, and believe strongly to run
>richer. Peak power appears to be richer at 12.6 according to Probst. The
>14.7 setpoint is used primarily due to emissions. (Thus the wideband O2
>sensors and the injector pulse stretchers on the market for performance
>folks)
>
>I'm thinking you have head temp sensors? If I get serious on this I want to
>set up individual sensors due to the cooling airflow on the pinz. The
>rearmost cylinder supposedly runs hotter anyway, so I don't want to make it
>worse by being lean.

The Pinz is much more even than a VW.


>After taking another look at the DIY Wideband, I may rethink the EFI issue.
>(Sure wish I had caught the kit order!)  I would need to see if there is a
>cheap wideband O2 sensor available as well.

I am not yet convinced that part throttle in an air-cooled engine should be
richer than 14.7:1 but I may need to play with the PID terms to make sure
the A/F ratio swings are not too large.  Obviously there is a greater risk
than in a watercooled engine if we go lean.

>Well, good to chat. We'll have to stay in touch on this!
>
>Thanks,
>
>Alan
>
>
>----------------------------------------------------------------------------
>To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes)
>in the body of a message (not the subject) to majordomo at lists.diy-efi.org
>

Ron Schroeder
WD8CDH
E. E. S.
wd8cdh at bnl.gov
rjs at bnl.gov
ron at 112motors.com
631 344-4561 Day
631 286-5677 Nite
----------------------------------------------------------------------------
To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes)
in the body of a message (not the subject) to majordomo at lists.diy-efi.org