Would the 749 ECM be the best choice for super/turbo application? Considering it is used on the Syclone and Typhoon (both turboed) and it is speed density with a 2-bar MAP sensor, should I consider it?

Please go easy on your answer(s). I am definitely ECM/EPROM illiterate. And thanks Glenn for suggesting this system. I never knew it existed.

------------------
Willie

Supercharged 1987 305 IROC-Z, Daily-Driver, Emissions-Legal.
12.57 @ 111 mph.
12.04 @ 114 mph (50-hp nitrous).
http://members.optushome.com/au/downunder1/rides/willie/willie.html

1987 "20th Anniversary Commemorative Edition" Z28 Convertible -- Super Chevy Show Class Winner, 1998.

 

That is the very set up I am going too this spring once I finish plumbing the pipes on my Malibu. Check out the SyTy.org site for some more info..if you already havent..It's my understanding that Grumpy has done this very thing on a TPI small block. Good Luck, Robert

------------------
79 Chevy Malibu Cpe
305 TPI/700-R4,
Custom Turbocharged,
ported upper and lower intake,
214,224 duration .450I .465E lift
749ECM,custom eprom,
Website:
www.turbotpi.homestead.com/SATURN5.html

 

I am sorry for butting in here Willie, but I wanted to point out that you have an ATI Procharged D1SC running 10 or 12 psi (I forget which) and you are planning on running 15 psi as soon as you get the ecm issue resolved (that I do remember).

Here is a link of Willie's car and it is a "must see".

https://www.thirdgen.org/messgboard/...ML/000463.html

But I just wanted to make sure that everyone knew that you were talking about a serious supercharger here and you need to know ALL your options and the pros and cons of each.

You've worked far too much on that car to let an ecm get in your way.

 

This makes maybe 4x I've said it:
Very Nice Installation.
The 7 little guys have been chattering nonstop.

I'll tell ya, every .2" you can shorten the distance form the Air Cleaner to the S/C counts. Often overlooked but critical.
Again, real nice

 

Can you elaborate?

And back to my original question, has anyone tried the 749 ECM with a turbo or supercharger?

Willie

 

Willie, maybe you should consider attending Bruce's "EFI POWWOW" on Mar 17/18. If I could weasel the time off work, I would love to attend.

Bruce, I believe Willie is looking for an alternative to his 165 ecm. I feel Willie's most effective (but not overly expensive or complex) is to go with the 749. For my own personal knowledge, I would like assist Willie on this conversion and share the results with the others on this board.

However, if you have any other ideas or insights, we would be very interested in your ideas.

I noticed that the 749 appears to be a "derivative" of the 730 with the exception of one missing quad driver but an additional injector driver FET. Does this mean that a 730 could be converted to work like a 749?

I recall that you stated that a 730's machine code could be modified to handle a 2 Bar MAP, though I was a tad unclear what you meant in that post. I am purchasing TunerCat's Disassembler as I personally would like "twiddling the bits" on my 730 and would be curious on any suggestions that you may have on that.

Lastly, are you aware of any "hacks" on the 749? If none exist, I was planning on disassembling the 749 and comparing it to the 8D to develop a hack for the 58.

Willie and I are prepared to do our homework, we would just like to get your opinion on this project and any feedback you could offer. I think this would be some interesting information for this board to share with others.

Thanks in advance Bruce.

 

Just out of curiosity, did you guys ever dive into this?

 

I'm interested in any new developments here also. We'll soon start tuning on a 455 Olds with an 8-71 Blower. It's set up with a 730 ECM right now with the MAP sensor upstream (unboosted). I'm been reading a good bit here and I'm telling the guy were probably going to have to get a 2 Bar sensor into the intake manifold and go with the 749 ECM. How do you get the 749 to drive 8 injectors? Any who, If we could just modify the 730 we'd be in like flin!

Our other option might be to go with an FMU.

 

The 749 $58 (like the 730 $8D) has a constant for the number of cylinders. You would set it to 0, and the 749 will think it is firing 8 injectors instead of 6 (Dec value 192 IIRC).

 

I guess I am confused now. I thought the 730 and 749 were both batch mode EFI systems. I thought the constant for how many cylinders were present was for microcontroller timing and engine timing only. When the ECM says 'fire injectors' it doesn't sense or care how many it fires.......it just turns on power FETs. Will the FETs on the 749 supply enough current to 8 injectors instead of 6?
I read that it is possible to have the MAP sensor before the supercharger. How does this work.........is it reading a scaled version of the manifold pressure? I don't understand how that could work properly from a theory point of view.
Why not just put two regular MAP sensors in parallel at the manifold?
Thanks,
J

 

I'll tell ya, every .2" you can shorten the distance form the Air Cleaner to the S/C counts. Often overlooked but critical.


im sorry to post this on the prom board but also was wanting to know if bruce could add some more insight on this (it make sense but how much?)
i have a procharger camaro and originally they wanted you to install filter right above headers which took in way to much heat
so i welded a 4" 90 degree elbo tgrough fender well and routed flexable vacuum hose from behind wheel to under nose to a cone filter - the car picked up .2 tenths by doing this, moral of the story the air cleaner is about 2 1/2 - 3 ft from the S/C now soo shoud i try to find diff means? i dont want to lose the clean look it has now .
thank you
(also currently purchasing own burning equip)

 

ive also been looking into this for some time now.just wondering has anyone accomplished the ecm swap with no ill effects? i think i'm going to try it this spring and could sure use a good push in the right direction.anyone have any more info on the swap? such as what pins on the computer are the same or are the plugs totally different?
well guess i'll have to try to scronge up a ecm and compare them

pete

 

For every 1% reduction is intake tract restriction loss, there is a 2% increase in HP.
Changing from 3 to 4" pre turbo plumbing on my GN had to be close to 15 HP, and it spools alot quicker. Enough difference to have to change the chip some.

 

Same connectors, thou a few minor pin changes.

 

For accuracy you'll want to read the manifold MAP, ie NOT be pre charger.
The 749 easily handles 8 saturated injectors.
remember to use a 8 cyliinder memcal.
I've run a 749 with 6 peak and holds, and it took hours at WOT to kill the injector driver.

1-2-3 in 1 bar MAP sensors doesn't change them to reading 2 bar.
At over 1 bar your talking pressure (ref to atmos).
For the price of a sensor might as well just have it right

I oersonally havent used a 749 for a v8 but Carl Summers has done a bunch of them, you might try looking for him.

 

Thanks for the response Grumpy. The info. of the injector drivers is good news. I am new to super/turbo charging so I am not up to speed on how the MAP sensors work. I don't even know what cars came with a 2 or 3 bar map. I guess the GN and TA did. I haven't priced these MAPs yet.....I am still justing working on building the header for the turbo........long way to go.
cheers,
J

 

GNs, and syclones used 2 bar MAP sensors.
89 Turbo Trans Am used a 3.

Dale at Lockitup@bright.net is good for selling em at a good price