simplest MFI system?

haycait911 · haycait911's Garage

what is the bare minimum you can use as an MFI system?
ideally without warm-up and microswitch/fuel cut-off systems, or anything else not necessary for go-fast. in buying MFI stuff for my 2.4 engine, as is my nature, I went a little nutty. now I have a STACK of MFI stuff and another couple of 2.4T sets coming, and a pump or two.

I'd like to convert this engine:

3.0 dyno day - a pleasant surprise

to MFI. I'm not worried about rough warm-up, or emissions issues. what is the bare minimum I can run for components? simple = good. I'd like to keep headers and the Bursch, and probably run K&N's or screened tall stacks. any thoughts much appreciated. thanks, Don.

Flieger · Flieger's Garage

The shut-off solenoid is integral to the pump, as is the thermostat. You might as well use them. I noticed much better running with the fuel shut-off on the over-run. Crisper, cleaner, smoother throttle response, more engine braking, and better fuel economy. No popping noises, black soot, or stumbling. I run with a screw for the thermostat enrichment becuase I have headers, works fine here in Southern California. Other than that, there is only the starting fuel squirters which I find make a surprisingly huge effect. I cannot start the car without it, even on warm, nice days.

haycait911 · haycait911's Garage

do you run a hot air hose to the thermostat? any chance of a pic or two? thanks, Don.

911st · 11-08-2009, 06:33 AM

On a 72 2.8 MFI twin plug I built some years back I had a block off plate made for the thermostat with a screw through it set to the length of the thermostat pin when hot. I actually put a spring and knob on it so I could easily adjust my AFR externally.

For the primer system I put a button on my dash to use for cold start. Not sure I really needed it. I also had the mechanical throttle lever between the seats so I could step up idle speed if needed.

I kept the fuel cut off but do not think it worked as I had a lot of nice popping on de-accel.

Double check this info as it has been a while.

911st · 11-08-2009, 06:45 AM

Second thought.

You might contact Gus and Pacific Fuel Injection or some other builder you like and see if they can set up a pump to work with your set up and cams. I would send them you TQ curve.

There is a cam for the later pumps (RS) and specs for a 3.0 w S cams & 36mm intake ports. When we go custom things can be a bit of a challenge when converting to MFI. If it is a race motor and you do not care about drivability it is not to tough. With your flat TQ curve you could probably just put a 2.4T pump on it, faten it up and get it to run perfictly from 4100 to 5500rpm at WOT. It is if you want it to have manners under 3k rpm and part throttle where a good match comes in.

356RS · 356RS's Garage

Don, I run a 2.7 short stroke, MFI, 38mm intake on TB's, with 10.6 comp. GE-60 cams, headers and twin plug. I made the MFI system very simple. No shut-off or warm up thermostat and K&N water shields. I have no cold start fuel squirter's. I use the adapter plate with lever and cable to control the warm up and cold start. I have it adjusted so for cold starts the plunger is all the way out causing the MFI pump to go full rich which gets the engine started in about 2 seconds of cranking. As soon as it starts I adjust my knob a little towards lean and let it warm up. Works perfect. I might not have the best fuel ecomony I could, but that was not on the top of my list. I do not suffer from any popping, stumbling, back fires or black soot. The driveability is without compromise. There is some time consuming MFI tuning to get this all working right.

jbell959 · 11-08-2009, 08:10 AM

Here is the pump on my 2.5SS. Similar to Mark's but I also removed the baro cell and plugged the oil fittings (it's filled with Mobil 1)

.... and I love the collection

al lkosmal · 11-08-2009, 08:10 AM

Don,
Nice MFI stash! You're as bad as I am, during a project. I am now trying to limit myself to three of everything. While searching for MFI parts for my 71E, I ended up with two or three of everything, too...until I found parts I really liked....slippery slope, but a nice one.

Regards,
al

911st · 11-08-2009, 12:07 PM

Cool pump!

911st · 11-08-2009, 12:10 PM

Last full set of MFI take of parts I bought cost me $20 for the box.

How much should I expect to pay for a good set of core's with injectors, lines, pump, TB's & linkage?

Thx.

356RS · 356RS's Garage

2 weeks ago on this site I bought a complete 2.4T MFI setup less the plastic air cleaner and a few TB linkage rods were missing. Paid $1000.

signature65 · 11-08-2009, 01:01 PM

I have headders on my 2.4T MFI so I have no thermostat. It runs rough when cold but when warmed up its a dream. I just use my hand throttle to keep it ideling....start around 2K RPM....then within a few moments I can drop it to 1200 RPM and it idles there just fine. After about 5-10 mins she idles at 900 without issues.

arrivederci · 11-08-2009, 03:08 PM

Quote:

Originally Posted by 356RS

2 weeks ago on this site I bought a complete 2.4T MFI setup less the plastic air cleaner and a few TB linkage rods were missing. Paid $1000.

...and considering how quickly they went, I think I underpriced them a little bit. Glad they went to a good home.

signature65 · 11-08-2009, 03:51 PM

jbell959:
356RS:

Does someone sell the bracket that replaces the thermostat....both you two have the same looking bracket.....I WANT!

Not to hijack.....

911st · 11-08-2009, 03:54 PM

Wow.

No one used to want these at one time. Now they are golden it seems.

Guessing a pump about a grand to have a pump converted to RS specs?

Bought my last RS space cam for under $300. Are they still available?

How much to have the TB's opened up w larger butterfly's and the shafts done?

Have a project in mind. I loved my 2.4T, 2.8RS and 2.4S MFI cars.

Thx.

jbell959 · 11-08-2009, 03:56 PM

Darren: I bought mine from Henry at Supertec Performance

Flieger · Flieger's Garage

Photo as requested

haycait911 · haycait911's Garage

Quote:

Originally Posted by 911st

Last full set of MFI take of parts I bought cost me $20 for the box.

How much should I expect to pay for a good set of core's with injectors, lines, pump, TB's & linkage?

Thx.

I MAY have gone a little overboard, but I figure this stuff is money in the bank, they ain't makin' any more of it.

I bought this set-up on pelican for $1300. 2.4T

and a very nice one from Aase motors, on ebay, for $1500 also 2.4T

jbell959 · 11-08-2009, 07:06 PM

Don - I was over at Aase Motors a few weeks ago picking a part up from Allan and he showed me the MFI parts.... you got a very nice setup.

I've managed to collect a bunch of MFI stuff also... every few months I need to sell some stuff so I can walk through the garage - it's a sickness

haycait911 · haycait911's Garage

thanks for the input and pics guys. Mark, that's the kind of system I'm thinking of. Flieger, I like the simplicity of yours too. a cable control for cold start and warm-up is my kind of thinking.

I was bootin' around in my car today.

I'm not sure I want to mess with this engine. it would be a serious dissappointment to convert to MFI and have LESS hp/torque. and it's hard to imagine this engine finding any more than it's got now. the cams are the heart of this thing and changing them might ruin the combo.

I've got a line on a core 3.0 that I think I'll pick up to do the MFI thing on. also will give me a bit more time to gather the bits and pieces and plan things out. I'll be putting an E MFI system on the 2.4 for the green car. that will give me some experience in MFI before doing a custom system.

funny, all this and I've NEVER driven an MFI car.......... yet.