Megasquirt EFI with Megasquirt on my 85 GS 12a
#1
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EFI with Megasquirt on my 85 GS 12a
Now that I have succusfully installed megasquirt on my Turbo-GXL I feel comfortable enough to try it again. My current problem with my FB is I was a dumb @$$ and sold my racing beat intake and 600cfm holly. My factory 12a engine has a broke apex and I installed my race ported 12a last weekend, I have everything to get this car running again accept the intake and carbs.
I need ideas to get this EFI thing to work on the old 12a. My first thought was to use the 6 port intake that was in my GXL and get an adapter plate to fit it to my 12a that I saw on ebay, but now it's sold... so i need more ideas. Should I just stick a 13b in it?
I need ideas to get this EFI thing to work on the old 12a. My first thought was to use the 6 port intake that was in my GXL and get an adapter plate to fit it to my 12a that I saw on ebay, but now it's sold... so i need more ideas. Should I just stick a 13b in it?
Last edited by quasar; 07-23-07 at 05:06 PM.
#2
Slave to the Rotor!
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hey Rus, it's Ken, AC's friend, my vote would be picking up a TWM stlye throttle body and a sidedraft wrap around intake ...either that or there are TB's that fit a holley bolt patern that would work on a RB intake. Either way TB inject is the way to go since 12as don't have injector bungs in the irons and you're going to need secondaries for that big port job. Time to spend some money brother!!
#3
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I dont know how much time, effort, or money you're looking to put into this, but if it were me, I'd pick up a set of CBR600 f4i (just cause im familiar with them) throttle bodies and make a custom manifold to match. The TB's have injector bungs incorporated into them, and running them with a custom, short-runner manifold would not only look awesome, but im sure would match the quick-reving characteristics of a race-ported 12a, and be more responsive to part-throttle than one large TB.
You can get pieces of steel cut for the engine-end of the manifold, run some thin-walled pre-bent steel tube (of the same OD as the TB's) inside them, and have them all come together up at the top to hose-clamp on to the bottom of the TB's (thats how its done on the bike anyway). Then you'll either need to rent a welder (if you dont have one already) or have someone weld it for you, and machine the engine-side of the manifold plate flat... but now you have a very custom setup that should flow quite a bit.
You can get pieces of steel cut for the engine-end of the manifold, run some thin-walled pre-bent steel tube (of the same OD as the TB's) inside them, and have them all come together up at the top to hose-clamp on to the bottom of the TB's (thats how its done on the bike anyway). Then you'll either need to rent a welder (if you dont have one already) or have someone weld it for you, and machine the engine-side of the manifold plate flat... but now you have a very custom setup that should flow quite a bit.
#4
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I have another option, I will try and find my photos
This is a common way a 12AT is done in Australia
You can see there is a ~1" thick bit of aluminium that bolts to the 12A motor, then a 13BT intake bolts straight onto the adaptor which is allready bolted onto the motor.
You can have injectors placed inside the adaptor. The adaptors themselves cost about $130AUD probably only $100USD.
You get progressive throttles, and you can easily use 550cc primary injectors combined with 1600cc indy blue secondary injectors. I'm using siemens 870cc secondaries which are a harder fit however.
My intake has since been cleaned painted, and had the primary injectors installed in the adaptor plate.
This is a common way a 12AT is done in Australia
You can see there is a ~1" thick bit of aluminium that bolts to the 12A motor, then a 13BT intake bolts straight onto the adaptor which is allready bolted onto the motor.
You can have injectors placed inside the adaptor. The adaptors themselves cost about $130AUD probably only $100USD.
You get progressive throttles, and you can easily use 550cc primary injectors combined with 1600cc indy blue secondary injectors. I'm using siemens 870cc secondaries which are a harder fit however.
My intake has since been cleaned painted, and had the primary injectors installed in the adaptor plate.
#5
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ooh, that looks nice! I wasnt thinking along the lines of going turbo, but that is pretty clean. Where did you get the replacement for the stock TB elbow? Is that a one-off special, or something I could pick up somewhere? I don't have access to a welder myself, so i just have to be content with buying some things.
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I dont know how much time, effort, or money you're looking to put into this, but if it were me, I'd pick up a set of CBR600 f4i (just cause im familiar with them) throttle bodies and make a custom manifold to match. The TB's have injector bungs incorporated into them, and running them with a custom, short-runner manifold would not only look awesome, but im sure would match the quick-reving characteristics of a race-ported 12a, and be more responsive to part-throttle than one large TB.
You can get pieces of steel cut for the engine-end of the manifold, run some thin-walled pre-bent steel tube (of the same OD as the TB's) inside them, and have them all come together up at the top to hose-clamp on to the bottom of the TB's (thats how its done on the bike anyway). Then you'll either need to rent a welder (if you dont have one already) or have someone weld it for you, and machine the engine-side of the manifold plate flat... but now you have a very custom setup that should flow quite a bit.
You can get pieces of steel cut for the engine-end of the manifold, run some thin-walled pre-bent steel tube (of the same OD as the TB's) inside them, and have them all come together up at the top to hose-clamp on to the bottom of the TB's (thats how its done on the bike anyway). Then you'll either need to rent a welder (if you dont have one already) or have someone weld it for you, and machine the engine-side of the manifold plate flat... but now you have a very custom setup that should flow quite a bit.
#9
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electric-controlled secondary plates? it'll probably be pretty hard to implement that, are you planning on using a stepper motor to do that with some sort of aftermarket module, or are you converting the whole thing to throttle by wire? Id think it would be easiest just to hook up some sort of mechanism to delay the opening of the secondaries similar to the stock TB.
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electric-controlled secondary plates? it'll probably be pretty hard to implement that, are you planning on using a stepper motor to do that with some sort of aftermarket module, or are you converting the whole thing to throttle by wire? Id think it would be easiest just to hook up some sort of mechanism to delay the opening of the secondaries similar to the stock TB.
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Last edited by twister7; 07-24-07 at 12:22 PM.
#13
SAE Junkie
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Using quad throttles you lose the progressive action of the secondaries and you also loose being able to tune by MAP because there will be no way in hell you will pull decent vacuum with throttles that big.
In Australia we also use 48IDA Manifolds with 45,50, and 55mm twin throttles sitting on top. They make more power than the stock FC setup, and have less of an addition in size than your figures :S Think that tells you that adding the size of the throttles like that doesn't work, you'd need to work out the surface area not just add up the radius's.
Another option is contacting someone like www.xtremerotaries.com they make some very nice gear ($pricey)
In Australia we also use 48IDA Manifolds with 45,50, and 55mm twin throttles sitting on top. They make more power than the stock FC setup, and have less of an addition in size than your figures :S Think that tells you that adding the size of the throttles like that doesn't work, you'd need to work out the surface area not just add up the radius's.
Another option is contacting someone like www.xtremerotaries.com they make some very nice gear ($pricey)
#15
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most bike TB's do have a collected vacuum signal, and I think i've figured out a way to get more progressive throttle opening on the primaries, and delay the opening of the secondaries until about half-throttle, although testing it will have to wait til i get my next car and start setting it up (either an FB, or my "project" car that is waiting for more time and $)
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I'm going to think about this for a while. The first bit of money I get i'm taking the GXL to the dyno to get tuned. So i'm in no hurry to get the fb together yet. I do like the RB intake with TBI setup the best so far. remember fellas, megasquirt was created for the budget minded, i'm not looking to spend $1000 or more to get this thing back on the road when I can go the usual route and have it done faster and cheaper. But it will be cool to have an EFI FB with a 12a in it.
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Guess u could just use rpm vs tps (alpha-n) instead of rpm vs map (speed density).I think the bikes are set up to use the map only on very small throttle opening then some how switch to tps instead of map.But if the secondary plates were controlled electrically rpm based i think u could work around the weak map signal, some what,only problem there is you could not control each 2nd throttle plate separately they are all hooked together , then i guess u could take the two center secondary blades out so u would be using only two 42 mm tb until engine demands more air flow sorta like the 5 & 6 ports on the na's except electrically controlled for example at 3500 the two otter 2nd tp are open 10% then at 4000 they are open 20% so on and so forth, just like a vacuum secondary holley carb the secondary open slowly with engine air flow demand . lol now just figure out how to make the manifold runner length change with rpm like the 4 rotor Mazda r26b (TIMS) and you are all set. Any ways this would be a big pain to do any way and with no way to control the secondary plates like this (that i know of) is there any way to do this Ken (soft ware wize)? Really i think his best bet would be to adapt a s4-s5 manifold and tb over to the 12a!
Last edited by twister7; 07-24-07 at 11:23 PM.