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3.2 intake on 2.4 motor???

I'm wanting to do a EFI upgrade on my 2.4 MFI motor the basis or the custom EFI I plan to use will be the manifold off a 3.2 motronic injection linked to a after market ECU.

What I need to know to proceed with my project is are the stud patterns for the air intakes the same on all 911 blocks ie will the 3.2 air intake fit my 2.4 block??


Thanks Steve
Old 07-30-2005, 02:37 PM
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custom EFI

Custom EFI would make an improvement for the 2.4. And yes, as part of the work, will be able to adapt/fit/mount the 3.2 intake/EFI.

Are you going to increase CR?

Good luck.

Regards,
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Old 07-30-2005, 06:30 PM
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No plans to raise the CR initially but im already curious as to weather this has been done to my engine in the past!

Steve
Old 07-30-2005, 11:42 PM
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Do you know for sure that your MFI is the problem yet? If all of the components are still there and are in decent shape, the MFI could probably be sorted out. Where are you located? Maybe a local MFI guru could help out.

The studs should line up for the intake, but the ports wont be anywhere near the same size. It could be made to work, but i think you are going to see a performance drop if this is the only thing you change on the motor.

as far as using an aftermarket ECU and wiring, the tbitz system would probably be the cheapest at ~$1500. You are going to be into the intake for $500 minimum. So for $2k you might have all of the parts you needed. I dont know how much it would cost to sort everything out.

You can pick up a complete 3.2 with all of the wiring, etc for under $5k these days and sell your 2.4 off to recoup some of the cost. When its all said and done you might have as much in it as with the induction change and aftermarket ECU. This is also a farily well documented swap so it could be less of a headache in the long run. You will need an oil cooler though, so figure another $1500-$2000 on top of everything else.. You will also need a different fuel pump and should swap the fuel tank, but selling off a working MFI fuel pump can offset these costs. This is what Im doing in one of my cars.

You could probably ebay the MFI setup and be into a set of 40mm carbs for less $500 or so. This is obviously the easiest and cheapest option.
Old 07-31-2005, 07:20 AM
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My MFI system is now working ok again however im looking at the longer term what I want to end up with is a 3.0 block running EFI most probably the megasquirt kit from tbitz. I figured I could get the system up and running on my 2.4 using the manifold and injectors and fuel rails of the 3.2 as I know a breaker that has the whole injection system off a 3.2 for sale at a resonable sum. I have disscussed this with tony from Tbitz and he seems to think the fuel rail and injectors off the 3.2 should work fine with his basic kit ie minus his rails and injectors. Then once it is up and running if I ever get the opertunity mainly the cash it would be a fairly simple swap to take my 2.4 core out and exchange in a 3.0 or whatever else!

The reason im wanting to do this on my 2.4 initally is because although my MFI is working fine at the minute my throttle bodies and intake stacks are in bad shape there cracked where the bolt holes are and pretty much beyond repaire I took them to try get them welded up but as there magnesium alloy it didnt take. So im figuring my best option is to opt for upgrading to an EFI system that could also be used when I manage to find a suitable larger transplant. Once the car is finnaly on the road im then planning on getting a 3.0 that needs a bit of work as a rebuild project to keep me busy therough the winter months!
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Old 07-31-2005, 09:11 AM
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Also Y do you think this system would cause A drop in power? The fuel delivery and atomization of the fuel should be as effecient as the MFI the only advantage MFI has got is that its sequential where as the megasquirt without big modifications works on batch fire, but from my research theres nothing to be gained from sequential over batch as far has HP goes!

As you stated the port size is 8mm bigger on the 3.2 to the 2.4 but wouldnt this actually benefit the engine from using a larger intake manifold obviously the limiting factor been the smaller port size on the 2.4 but if not better with the larger manifold how could it be worse?

Steve
Old 07-31-2005, 12:00 PM
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One issue that I'd see is that there'd be a step down in diameter from the manifold to the intake ports -- a bad thing. So let's say that you port the heads to match the manifold, then you will find that the velocity of the intake charge may drop compared to the MFI throttle bodies, thus causing the turbulance and mixing to decrease at low rev's. Sure it will flow ample air at peak RPMs, but chances are you only spend a few percent of your time at that engine speed. At low rev's you might have problems keeping the fuel suspended in the air which will result in poor running and a drop in torque at those engine speeds.

If you've got MFI, I'd think that it's a better idea to get the throttle bodies fixed or replaced. They show up on ebay relatively frequently. In the future you can use the same throttle bodies on a different engine configuration with a mapped EFI system. Generally, intake configurations with individual throttle bodies provide better performance and throttle response compared to systems that have a single common throttle body and plenum.
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Old 07-31-2005, 12:56 PM
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Ok scrap the 3.2 manifold idea ive just had a good look at some closeup pics of this manifold and it seems like id would need to machine my heads as the injectors would be firing into the gasket between the head and the manifold. The 3.2 heads must have some sort of cut out in them for the injectors to fire into the intake port!

Old 07-31-2005, 12:57 PM
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How about carbs? Seriously, why not?
Old 07-31-2005, 01:09 PM
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The carb 2.4 was 10 horses less for starts! maybee better carbs on market but I like fuel injection! May try looking at getting my MFI manifolds fixed up (is it possible to get magnesium welded?) and look at trying to swap the MFI injectors for an EFI ones make some kind of adapter socket that will screw in and then take the EFI injector. I looked at this today when I had an injector out the injector hole seems a bit small though to get an adapter in and then the end of the injector through it, Anyone else ever looked at this?

Steve
Old 07-31-2005, 01:19 PM
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BTW, I've heard of guys converting carb bodies (say some cheap Zeniths) over to act as individual throttle bodies for an EFI set-up.
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Old 07-31-2005, 05:56 PM
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I'm about to convert my 2.4 to efi as well. Has found that the thottlebodies from a Suzuki GSXR 600 '01 will fit. You can buy them cheap on Ebay, complete with injectors, -rails and throttle potentiometer. They come apart easily, so you can set the spacing between the individual tbs to match with the heads. Im about to find out, whether its possible to find some motorcycle rubber manifolds that will match the bolt pattern of the heads, and have the right portsize (38>36mm).

Carsten
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Old 08-19-2005, 04:09 AM
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Quote:
Originally posted by Ceder2.4S
I'm about to convert my 2.4 to efi as well. Has found that the thottlebodies from a Suzuki GSXR 600 '01 will fit. You can buy them cheap on Ebay, complete with injectors, -rails and throttle potentiometer. They come apart easily, so you can set the spacing between the individual tbs to match with the heads. Im about to find out, whether its possible to find some motorcycle rubber manifolds that will match the bolt pattern of the heads, and have the right portsize (38>36mm).

Carsten

let me know how this turns out .Im reaaaaaaalllllly interested if this works . when done would this actualy bolt up or would you have to mod the throttle bodies to bolt to the heads

What do you have in mind for a brain and harness. Im thinking of a computer from a 6cyl BMW 2.5 liter and using a DME flywheel from another Porsche on my 2.4. What do you think?
and what is a (potensionmeter) do you mean (air flow meter)
Old 08-21-2005, 03:10 PM
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Quote:
Originally posted by herman maire
let me know how this turns out .Im reaaaaaaalllllly interested if this works . when done would this actualy bolt up or would you have to mod the throttle bodies to bolt to the heads

What do you have in mind for a brain and harness. Im thinking of a computer from a 6cyl BMW 2.5 liter and using a DME flywheel from another Porsche on my 2.4. What do you think?
and what is a (potensionmeter) do you mean (air flow meter)
Interesting idea, fitting a DME from a 325i. Personally, I'd probably want to use a 3.2 Carrera wiring harness and sensors, as all the wires are the right lengths to fit a 911 engine and all the sensors fit too. As for the 325i brain, I don't see where it offers anything a 3.2 Carrera brain doesn't, except for a lot more hassle getting it wired up (either configuring a new/modified harness, or replacing the connector on the end of the Carrera harness). Since you'd end up needing a chip either way - the BMW mix/advance curve is probably "close enough" but don't you want it perfect? - using the Carrera setup would be a little more $$$ and a lot less PITA.

Gotta say, though, if I wanted an EFI 911 engine with Bosch DME, I'd want to use individual throttle bodies - converted MFI TB's, gutted Zeniths, mcyc TB's, whatever - and then convert the DME to alpha-N. MAXX in Germany, for one, makes a kit for BMW M3's which would almost certainly adapt to the 3.2 Carrera motronic. It's infinitely tunable (mixture only) and works REALLY well. With a big set of ITB's, you'd have the best of all possible worlds, IMO.
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Old 08-21-2005, 04:18 PM
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