Cheap, simple, non-factory FI solution, parts, etc..., Type IV - This oughta be fun... |
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Cheap, simple, non-factory FI solution, parts, etc..., Type IV - This oughta be fun... |
Gint |
Jun 4 2009, 04:39 PM
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Mike Ginter Group: Admin Posts: 16,083 Joined: 26-December 02 From: Denver CO. Member No.: 20 Region Association: Rocky Mountains |
I've thought about doing a Megasquirt for a while now to replace my carbs. I have a Mallory that works great, so to keep the initial cost down as well as keep it simple, I want to do fuel only, but have an upgrade path available for ignition later. Ideally if this could be done for under $500 that would be fantastic.
So... What is the easiest, cheapest, most simple solution for induction parts? Throttle bodies, injectors, TPS, etc...? Which MS unit has the flexibility to do fuel now and ignotion later without starting all over again with a different ECU? Engine is a 2056 that is built on a 1.8 case and heads with a 2.0 crank, rods and P/Cs. Currently running dual Weber 40 IDFs. (IMG:style_emoticons/default/idea.gif) (my own note: 40 IDF 70 9A, Italy) |
McMark |
Jun 9 2009, 12:31 PM
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#2
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914 Freak! Group: Retired Admin Posts: 20,179 Joined: 13-March 03 From: Grand Rapids, MI Member No.: 419 Region Association: None |
Before I start this post, a definition. When I say modern fuel injection, I mean MegaSquirt/SDS/MicroSquirt/Motronic (probably)/etc.
Soooooo, you can usually set up modern FI to use either of two metering systems, Alpha-N and MAP. All FI systems are trying to 'guess' the amount of air entering the system so that the fuel can be 'matched' to that air. Alpha-N guesses by using a TPS to know how far open the throttle is. By knowing how far open the throttle is, you can approximate how much air is getting in. If you don't have, or don't want a MAP sensor, you can use pure Alpha-N systems and get them to work fine. MAP guesses by measuring manifold vacuum and translating that value into an air quantity. MAP sensors need a common vacuum source from all intake tracks, or from a common plenum. MAP sensors can get 'confused' by cams with valve overlap which make less vacuum at idle. So with those cams, you won't get a nice 'usable' sensor reading until higher up in the RPM range. The solution most modern FI systems use is a blending. If you have a wild cam, you can use Alpha-N at low RPM since MAP isn't getting a signal, and then at some RPM value start using MAP as your main sensor. Those blending systems are not usually an all-or-nothing system. AFAIK, in MegaTune you can set a 'blending percentage' which will average the output of both systems at a variable bias. So at idle you can use 80% Alpha-N and 20% MAP, and you can customize that bias up the RPM range. Okay, that post is long enough. Keep 'em coming, Gint. (IMG:style_emoticons/default/biggrin.gif) |
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