Converting to MS on a 40hp/1300?

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Re: Converting to MS on a 40hp/1300?

Post by petew » Fri Nov 18, 2016 3:56 pm

Jadewombat; The challenge with the dual manifolds is putting a TPS on the carb parts. Would really need 2? Or could I just put it on one side.

Piledriver; Why would I need full sequential? Surely just running the single injector into the port would supply enough for both? And I don't have TBI. I have a single 40mm TB.

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Re: Converting to MS on a 40hp/1300?

Post by Piledriver » Fri Nov 18, 2016 6:08 pm

petew wrote:Jadewombat; The challenge with the dual manifolds is putting a TPS on the carb parts. Would really need 2? Or could I just put it on one side.

Piledriver; Why would I need full sequential? Surely just running the single injector into the port would supply enough for both? And I don't have TBI. I have a single 40mm TB.
Its a matter of getting the same amount of air and fuel in both cylinders on each side.
The firing order makes this hard.
Air is easy, but if you batch fire on a siamese port (= single port) almost all the fuel sitting in the port will go in the leading cylinder. To get a uniform AFR, you have to spray hard only while the valve is sucking... preferably with an injector aimed right at each valve. Sequential also provides individual cylinder fuel% tables to balance things out further if needed.

Sequential with the siamese timing options allows this, and the code exists for this specific purpose.
If the fuel is mixed upstream at the TB, it will work no worse than a carb. You still need manifold heat.

I suspect EFI on a ~stock single port isn't going to provide much gain for the cost/effort.
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Re: Converting to MS on a 40hp/1300?

Post by Jadewombat » Fri Nov 18, 2016 8:55 pm

You should only need 1 TPS as long as both sides are synced correctly. The more I think about it though, a single manifold will make it easier with a center mount TB for what you're trying to do. Unless I'm mistaken, those dual carbs look like they had the same diameter manifold as a single, correct? In that case, nothing would be gained by running 1 single TB or 2.

Pile, if he did 4 squirts per cycle and set the idle to 1000-1100 it should be OK to balance things out?? Mounted at the top of the curve, those injectors should be far enough back to get a good mix with the airflow for both cylinders I would think.

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Re: Converting to MS on a 40hp/1300?

Post by Piledriver » Fri Nov 18, 2016 9:09 pm

Jadewombat wrote:You should only need 1 TPS as long as both sides are synced correctly. The more I think about it though, a single manifold will make it easier with a center mount TB for what you're trying to do. Unless I'm mistaken, those dual carbs look like they had the same diameter manifold as a single, correct? In that case, nothing would be gained by running 1 single TB or 2.

Pile, if he did 4 squirts per cycle and set the idle to 1000-1100 it should be OK to balance things out?? Mounted at the top of the curve, those injectors should be far enough back to get a good mix with the airflow for both cylinders I would think.

Draw a circle of 720 degrees, plot where the #1/#2 intake valves are open...
Then place 4 evenly spaced injector shots on the same plot and tell us where ~all the fuel is going to go..

semi-sequential would allow you to at least have fixed timing of inj. starting or stop points (and is just a setting, any batch setup should use it) but it won't help much, here.
...MS2e sequential code was originally written specifically to support this, the guy who wrote it has an ancient Cooper Mini... Those are actually worse as its a 4 cylinder with 3 intake ports... The two in the middle share a big port. :lol:
The sequential code exists because batch simply cannot work for siamese ports unless the cylinders are 360 out.
(half a 4-stroke engine cycle, and they aren't)

TBi with manifold heat wins for this odd application unless you go sequential/siamese...
Its still not going to make much more power, but you would be able to set up a uniform AFR on all 4 holes, which even the stock carb setup has issues with... Blown, it matters much more.
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Re: Converting to MS on a 40hp/1300?

Post by Jadewombat » Sat Nov 19, 2016 5:29 am

I see now. I was thinking it was 1 cylinder firing every 180 degrees and 4 squirts per cycle should be close enough to cover that (kind of like CIS--more fuel available than is needed at any given time). The other option I've thought about it the past would be 1 big injector mounted to a single TB in the center. Still some gain to be had over a carb.

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Re: Converting to MS on a 40hp/1300?

Post by petew » Sat Nov 19, 2016 7:04 am

Ok... will have to do some thinking then. Dunno how I'll fit everything in the centre. Hmm...

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Re: Converting to MS on a 40hp/1300?

Post by Piledriver » Sat Nov 19, 2016 10:59 am

Small TBi s exist, I don't know what's available in Oz tho.
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Re: Converting to MS on a 40hp/1300?

Post by Jadewombat » Sat Nov 19, 2016 12:45 pm

You can use a stock carb as a TB. Retro-fitting a TPS has been done many times. SDS's website had a write-up but I can't find it now, but of course there are several other write-ups. Plug off the jets on the carb and you'd have a nice compact TB in the stock location with the stock air cleaner. You could also mount the intake temperature sensor there.

Find out the ID of the tube needed for the injector boss, get some steel stock tube, and weld in a section of tube on the center section just below the carb. at about 10-30 degrees and maybe 30mm long then you're good to go. Tap in small line for the MAP sensor (manifold vacuum pressure) and on the exhaust side, a O2 bung for reference (I have mine welded on 3 + 4 side and it doesn't seem to care).

If you go crank-trigger ignition you'll really see some benefits in low-end torque, mileage, and the engine running a bit cooler. In either case, a carb. and mechanical distributor act in 2D mode. Engine speeds up, both give more fuel and spark. The above give you control in 3D essentially.

3000 rpms is not the same launching off the line, going up a hill, or cruising down the highway. A MAP and exhaust reference will adjust for what the engine needs under varying conditions.

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Re: Converting to MS on a 40hp/1300?

Post by Piledriver » Sat Nov 19, 2016 7:11 pm

injector can also go in the air cleaner shooting down the throat of the carb ala TBi, or an elbow if pressure feeding it etc.
Above the plate will atomize a little better at low throttle settings, plus you can hide it if so inclined.
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Re: Converting to MS on a 40hp/1300?

Post by petew » Sun Nov 20, 2016 10:47 pm

Right, so my turbo engine is coming home this week. This will go on the back burner for a bit, but I'm still keen to see it happen. Hmm...

If there's no rush I could always go the duals with the injector spraying in through the filter hat. :D

JW, can you post a link the this "SDS" mob, so I can check out how they do TPS sensors?

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Re: Converting to MS on a 40hp/1300?

Post by petew » Sun Nov 20, 2016 11:40 pm

Right, found it. Now if I can just work out which TPS I'm sposed to use.

http://www.sdsefi.com/tps.htm

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Re: Converting to MS on a 40hp/1300?

Post by Jadewombat » Mon Nov 21, 2016 9:01 pm

It'd be worth it to contact SDS. Even if you don't buy the full system from them, I'm sure they would sell you just the TPS sensor. They seem really laid back.

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Re: Converting to MS on a 40hp/1300?

Post by petew » Mon Nov 21, 2016 11:11 pm

Came across these guys locally, last night.

https://www.efihardware.com/products/c2 ... -and-Parts

Expensive, but it shows me what I need/need to make. I can buy most of these parts cheaper on ebay or similar.

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