Megasquirt II ---> First Step in Fuel Economy Build
 

I am planning on converting to EFI with the hope of increasing fuel economy. My current setup is:

72 C-20, Stock 350 build with Edlebrock Performer Intake #1408 Carb, TH350, 4.11 Rear, 235/75/R16 tires. Currently getting 10mpg city 13 highway.

The pickup is my DD. I have been researching Megasquirt II as the EFI controller with GM TBI retrofit. The Megasquirt II also has the ability to control my HEI.

After going EFI, the next step will be 700-R4 (or 200-4R) install, followed with a 350 rebuild down the road.

For those who are interested, you can read the manufacturer's carb conversion on SBC here: http://www.diyautotune.com/tech_arti...part1-nova.htm

The setup seems easy. Does anybody have experience with the Megasquirt? I would appreciate any advice, experience, etc.

Re: Megasquirt II ---> First Step in Fuel Economy Build
 

so it looks like about 600.00 and you get to prety much plug and play ?

Re: Megasquirt II ---> First Step in Fuel Economy Build
 

YOU'LL GET no better mpg than a correctly set up timing advance curve and carb

the ms II is still batch/bank fire, meaning they fire all the injectors on one side of the engine at the same time.. and if you're gonna use a tbi then. don't expect any gains other than you not getting your hands dirty changing the timing curve or fuel curve(map)

good luck..

Re: Megasquirt II ---> First Step in Fuel Economy Build
 

http://www.megasquirt.info/

Lots of info on that site. Looks like there are options for sequential.

Re: Megasquirt II ---> First Step in Fuel Economy Build
 

msIII sequental



http://www.msefi.com/index.php

http://www.microsquirt.com/index.php
http://www.megamanual.com/mtabcon.htm
http://www.diyautotune.com/?gclid=CN...FdRM5QodL2yK3g



he's looking at a tbi

he'll get no gains.. but a late 80's tpi with the msII will up the low end torque, and less throttle= more mpg

synquental will need crank wheel and cam sensor..

p.m. matt cramer over at B/S
HE WORKS AT DIYAUTOTUNE

Re: Megasquirt II ---> First Step in Fuel Economy Build
 

I suppose I should clarify some of the driving conditions that I face. (1) in Colorado, I drive at varying altitudes (between 4,500 ft and 10,000 ft). I believe MSII will account for the change in density of the air using internal baromiter. One of the problems I have with tuning my carb is the altitude changes when I start at 5,000 ft and drive to 10,000. What should I tune for in that situation?

Second problem I have is winter fuel, summer fuel. This is a real issue with driveability and may be related to improper tuning now? Not sure if MSII will account for the change in fuel, but I think changing my tune seasonally with MSII will be easier than carb?

Thanks for the help Stich & the gang.

Re: Megasquirt II ---> First Step in Fuel Economy Build
 

msII will adjust if you see the .
tables..

silverbuick is in ely nv.
and has the same issues and is running ms on his 455 buick and t bird..
p.m. him over at b/s (bangshift)
tell him mark sent ya..
he'll tell you what needs to be done and how..
as he was in the same boat you are in..

mountain ranges

Re: Megasquirt II ---> First Step in Fuel Economy Build
 

Go for it! I've used Megasquirt in the past and it is awesome. I don't think your mileage will be exceptional as others mentioned, but it will automatically compensate for air density etc,........ and hell, its just good fun to install and use! Tons of info as well..... I used they guys at DIYAutotune. They were nice to deal with and very knowledgeable....

Re: Megasquirt II ---> First Step in Fuel Economy Build
 

If TBI, why not just bolt on the GM unit? $150 in the j yard, including the throttle body (not included in $600 megasquirt), ECM and wiring. It'll adjust for altitude, it has closed loop feedback for changes in fuel (warning - it does not like over 10% ethanol). Just need to redo the 4 center manifold holes and you're good to go. Fuel plumbing will be the same with either system. If you get a complete donor harness with the 700R4 connectors you'll be all ready for that swap, can get a chip burned to ignore the trans in the mean time. Don't know about your area but around here you can buy a complete running 350 TBI 700R4 88-92 1/2 ton for under $1000. Could do the complete swap and then your 350 would be available for the rebuild, or you could rebuild the roller cam bock.
TBi will give a little better MPG (like, maybe 1). A lot better cold start and cold driveability, will adjust for altitude, and bette fuel control leads to great engine longevity.

if you go megasquirt might as well step up to port fuel. Where MS really shines is oddball (think dual TBI on an inline, or E85 port fuel on a 300 ferd). For basic 350 TBI it's hard to be the GM units.

Re: Megasquirt II ---> First Step in Fuel Economy Build
 

can the g.m. set up go from the basic tbi (easy to install) and then down the road to mpfi????????? nope..
why rewire the truck twice...
going with ms now he'd only have to rewire the injectors.. nothing else..
both will require fuel system changes when going mpfi..

Re: Megasquirt II ---> First Step in Fuel Economy Build
 

Thanks for all the great info. I checked out bangshift lots of great info there.

I see what you are saying Stich, if my carb was properly tuned, it would provide the same amount of fuel as a properly tuned TBI.

Re: Megasquirt II ---> First Step in Fuel Economy Build
 

ttttt

Re: Megasquirt II ---> First Step in Fuel Economy Build
 

Carb should get better than that. My 454 with approx 8.5:1 was getting 20mpg with 800 edel and th400 in my C20
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Re: Megasquirt II ---> First Step in Fuel Economy Build
 

I absolutely don't believe that.

Re: Megasquirt II ---> First Step in Fuel Economy Build
 

Thats fine, im not trying to sell anything. Maybe I can just tune better than you
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Re: Megasquirt II ---> First Step in Fuel Economy Build
 

That would be a VERY efficient setup! I've seen boatloads of carburated 307's and 350's that couldn't make 20 consistantly,, even here in pancake land (the Az desert) And he did say MPG,, if he intended KPG(kilometers) it would be more 'expected' at around 12.5mpg that most others get with a carburated big block.

Re: Megasquirt II ---> First Step in Fuel Economy Build
 

22.5mpg aus 12.5L100km. That was at approx 2000ft. 72C10 has a pm with my details on it. He can post it or someone tell me how to post the pm I sent.
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Re: Megasquirt II ---> First Step in Fuel Economy Build
 

72chevyK10 sorry.
it was a major surprise to me, 049 heads, flat top pistons stock cam .460/.480 from memory. Performer intake, hooker headers xpipe, front half exh twin 3" rear twin 2.5"- did this witb broken foot so didnt end up finishing exh. 33"tyres 3.73 diff. Had vacuum feed water inj tho that didnt seem to affect mpg but ran intake very cool. A/F meter wouldnt read past 16:1, lean out cruise portion only until drivability issue than backed up one step. Part throttle is 13-14:1 and wot is too rich at 11:1. When I fitted headers cruise ran at 12:1 so I am WAY off the chart with current rods and jets. I didnt mean to imply im a tuning master. Ive since swapped head after valve seat went(old motor, pistons were still coated in carbon so not too lean). Even under part load keep high vacuum.
Now it is 7-7.5:1comp no 3 cyl is 30+lb lower on comp test- like this before. Mow avg 16 mpg aus think 13us best ive gotten latly is 18aus 15us. Down on power alot. Still get 13-14us grossing 11-12000lb. Building a new short block shortly for it.
I may have just fluked it but ill try for 20-25mpg with new eng and 3.42 diff
Also, hei initial 18* total 36-38. Cant remember, check later but think it was limited to 20* vac adv

Re: Megasquirt II ---> First Step in Fuel Economy Build
 

First thing id look at is possibly a taller diff ratio? with 235/85R16s that were on my truck at 60mph it was doing 2500rpm with 3.73 diff.

Re: Megasquirt II ---> First Step in Fuel Economy Build
 

Seems like the topic got shifted a bit. But as far as the MS II, I'm currently putting one on my '67 inline 250, and I've really enjoyed dealing with the guys at DIYAutotune.com. While the base 350 TBI setup might be 'easy' to swap in, with the MS you can change out any part of the system and reconfigure it your self without sending your ECU to some guy to reburn it for you each time.

To me the MS II was more about doing all the electronics, hardware and tuning myself, so I really understand how things work, and how I can use it to build a better system.

I say go for it.

Shawn

Re: Megasquirt II ---> First Step in Fuel Economy Build
 

Google "305 mighty mouse", thread on jalopy journal forum. Went from 12mpg to 25mpg and faster 1/4mile times.
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Re: Megasquirt II ---> First Step in Fuel Economy Build
 

DONT FREAKING DO IT

Been there done it, wasted tones of money. I could have bough a Holley fuel injection kit for what I spent on that damn system.

I sent you an IM, ask away. My truck came with that set up.
Old owner got tired of messing with it and left it sitting on the side of the highway.
He had 7k in the truck and said f**k it because of Megasquirt.

It is fine for a toy, but not a daily driver.