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Fuel Injection

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MattP

MattP

Jedi Knight
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https://www.bgsoflex.com/megasquirt.html

I read about this system in Car Craft Magazine. It is a DIY kit for a fuel injection computer that can be programmed for 1 to 8 cylinders.

I remember someone on the forum a year ago or so working on (I think) fuel injecting an A-series and thought they might find this useful.
 
Megasquirt is a big big thing now for DIY injection, or to replace some stock systems. Lot of control over your fuel/air mixture. Unfortunately, it doesn't work well with siamesed heads, so the B-series is pretty much out unless you've got a x-flow.

Although I have to wonder about TBI and a supercharger. Wicked!
 
<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by Baxter:
Megasquirt is a big big thing now for DIY injection, or to replace some stock systems. Lot of control over your fuel/air mixture. Unfortunately, it doesn't work well with siamesed heads, so the B-series is pretty much out unless you've got a x-flow.

Although I have to wonder about TBI and a supercharger. Wicked!<hr></blockquote>

Never afraid to learn. What does "siamesed heads" mean? It sounds a head made of more than one part, but I am guessing.
 
I think he ment siamesed ports. A single port branches to two valves.
D

[ 02-24-2004: Message edited by: Dave Russell ]</p>
 
Looks interesting. I want distributorless ignition, traction control and launch control though, so I'll stick with the plan for the $1500 DTA system. =x

Its definatly got potential if you were wanting to do some performance mods to a fuel injected TR7 or TR8.
 
<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by Dave Russell:
I think he ment siamesed ports. A single port branches to two valves.
D

[ 02-24-2004: Message edited by: Dave Russell ]<hr></blockquote>

Would doing it as a two injector using the cases of a couple of SU's as throttle bodies maybe help? Using throttle body injection would more closely imitate the normal state of these cars and might compensate for the port issue? WAG there.
 
The problem is one of timing. Modern injectors shoot out the fuel in pulses, and the siamesed ports end up robbing the pulse from the adjoining cylinder (or something like that).
Run a google for megasquirt and siamesed and something will turn up. Those guys document everything.

The problem could, in theory, be avoided, by going to the old-school K-jet injection, which wasn't pulsed. But there's really no point in that, since you can't precisely control fuel maps in K-jet.
 
I don't see why the MegaSquirt controller would have a problem with Siamese ports (I can see why some installations would).

Siamese ports are problematic for sequential FI systems where injection volume and timing are intended for an individual cylinder. Heads with Siamese ports don't share the intake charge evenly and an injector at the common manifold port can't give each individual cylinder what it needs when it needs it.

MegaSquirt is programmable to operate as either batch fired or bank fired. This type of system is well suited to a throttle body installation where the injectors are far enough upstream to provide a uniform air/fuel mixture before the ports.

MegaSquirt is also very flexible in its programming allowing you to tailor it to many different installation configurations. I suspect that this broad flexibility also makes it easy to get lost when attempting to set one up.


PC
 
Pulled from the Megasquirt Yahoo group:

You tell MS how many events to expect per rotation, and it squirts
once per N events. You cannot control which event is used as a
trigger for the injection events, either, so on one start up MS
might use the cylinder 1 signal to fire and on another startup it
might use cylinder 3 or 4.

This is not a problem, except for possibly siamesed ports, such
as are seen on BL A-series motors (Minis, Spridgets et al) or on
TBI installations on 45 v-twins and such. (In these cases, the
injected fuel might be "stolen" by one cylinder's intake pulse...)

If you've got individual injectors per cylinder, don't worry about
odd fire injector timing.
 
Moss is coming out with a TBI fuel injection system for the B this spring. $1400 and no problems, even California legal. I'd rather have the Blower
driving.gif
 
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