mega squirt

[Patf10]

well im pretty sure im goin to put a mega-squirt system on my 360. my issue really is what type of TBI throttle body should i use. i was thinkin a GM from a 350? it just seems logical and about the same displacement. also hoping it will boost my mpg a few digits. i happen to have access to a megasquirt computer so i just need the odds and ends for the rest of it. any input or suggestions would be appreciated.

THanks
Pat

[tufcj]

You can use the GM 2BBL TBI or Holley's 4BBL TBI.

Does the Megasquirt do closed loop, automatic mixture adjustments from an O2 sensor? If not, I doubt you'll get it tuned any closer than a carb.

I ran a Holley on my Jeep, it was tuned very close using an exhaust gas analyzer on a dyno. I went to a Howell system (which is basically a 91-95 GM TBI system), I picked up less than 1 MPG. I will admit that it starts easier, idles smoother, the throttle response is crisper, and it runs at any angle (which is why I bought it), but mileage didn't change by any appreciable amount.

If your carb is way out, you might gain some, but a Jeep is like pushing a 4x8 sheet of plywood thru the air. I really doubt you'll gain more than 1-2 MPG, if that.

Bob
tufcj

[76-cj7]

How much did that Howell kit cost? and was it work it in your opinion?? Sorry to highjack the thred but im debating.....390 or 401 with some sort of injection system..........or Cummins 4BT 4cyl. turbo diesel.....it'll cost a bit but bring it up round 300 poines and bout 450 lbs of tq and still awesome mileage!!! Any one know where i could pick up a good rebuildable core?? All i want for the gasser would be a block and crank.....everything else will be aftermarket then the oil burner, all i want is block, head, internals, intake, and exhaust. Turbo will be aftermarket :mrgreen:

[tufcj]

I bought the complete Howell system about 5 years ago for $1250 to my door. It came with everything except air cleaner, fuel line, and a bracket to hold the ECM. It included a rebuilt TB, new MAP, water temp, and O2 sensor w/bung (this does need to be welded in), used GM ECU with a PROM custom burned for my cam/exhaust combo and a plug and play wiring harness. You just need to supply power/ground, and a wire to the fuel pump. They say you can use the factory fuel lines, but suggest you use bigger feed/return for best performance.

I installed it, including new fuel lines, in under 8 hours. The harness was well marked, and instructions were good. It fired first try, and aside from 2 bad O2 sensors, it's been flawless.

Howell will sell you whatever components you want, but I decided to buy the full kit just so there was no "finger pointing" in case it didn't work right.

www.howell-efi.com

Bob
tufcj

[Brett Polwell]

I would vote for the Howell system. Had a Holley Projection kit on a 360 for about 7 years. It worked better then a carb but I was constantly having to adjust it even with the closed loop.

I now have a Howell system on my 401 in a YJ that originally had a 4.0. I was able to use the stock in tank fuel pump and it works great. I haven't had to touch anything for 2 years.

My only complaint is that it doesn't like high RPM's. Its kind of like a built in rev limiter.

[tufcj]

I've spun mine to 6500 without a problem. The cam I run falls flat after 4500 though, anything past that is just more noise.

If you believe it's the EFI, call Howell's tech support. I talked to them a lot and asked about a million questions before I ordered it. I'd guess that it could be ignition or valve train that's limiting you.

Bob
tufcj

[Patf10]

mega squirt makes adjustments with the 02 sensor, you can use either a wide band or narrow depends if you want to spend a bunch on a sensor. but i wonder if id be better with a 4bbl over a 2bbl

[401 Pacer]

I would advise against any EFI that doesn't use an O2 sensor.

The optimal systems also integrate the distributor to control timing. This is a Closed Loop system, and the better ones include a knock sensor so all your bases are covered.

Otherwise you won't see much cost/benefit ratio.

EFI systems that lack an O2 will only give you slightly smoother running overall and are resistant to weird angles or bouncing around if you're an off-roader. Close Loop systems will give you better drivability, milage and (theoretically) lower emissions....but at a price!

For the money, a *WELL TUNED* fuel leaker (carb) can't be beat.

[Patf10]

but like i said it does use a o2 sensor, its a great system and i have seen it used on a few different setups. im looking for a few benefits, one run better offroad no more stalling flooding ect.. second if i gain a few mpg on the highway thats great, even a few digits, going from 10-12 to 15 is a big difference. i know alot of people do a GM TBI, but a mega squirt system is alot cleaner setup. And a smoother running engine is allways nice too.