thinking of upgarding from the 165 ecm maf system.. it's to buggy. should i move to a sd system.. or aftermarket system like the holley system. im running holley stealth ram intake. what do you think i should do...

 

The Holley system is SD the same as the '90 - '92 TPI ECMs.

The important aspects of which ECM to go with is emissions and driveability. Emissions isn't going to be supported with the aftermarket. No EGR, no CCP, and only some have closed loop to handle a cat-con to get the car through a sniffer.

For driveability this is a tradeoff when going aftermarket. These ECMs don't run code as refined as the GM stuff. For the best in idle quality, tip-in, and so on will be had with a GM ECM. Items such as TCC lockup are also an after thought in many after market ECMs.

RBob.

 

I'd suggest Accel Gen 7 DFI, but that's because I have it. It has everything that you might want, and I've seen quite a few cars that run it (including my drag car). It does support everything from dual electric fans (that can turn on independantly of each other) as well as converter lock up, 3 stages of nitrous, and phased-in turbo boost. Can't get much more flexible than that!

 

i love my fast xfi. i think any of the aftermarket systems are much easier to tune than the factory. But some people (smarter than me) seem to figure out the factory stuff.

 

well i think for now i might go with a sd set repin my harness..

 

i think MAF is easier to tune than SD. I was driving my car the day of startup with MAF last year. This year with SD, i'm having hell of a time just get the car to idle/start on its own!

SD is picky compared to MAF. MAF can handle anything you throw at it. SD wont be great with big cams that may idle at 70-80 kpa. MAF may max out early but you have lots of fuel to add with PE mode

 

I'd have to disagree with SD not handling "large cams". I have a "large cam" engine, and I have no issues with idle, acceleration, or WOT with a SD system (Accel Gen 7). My motor is stroked, cammed, and has alloy heads on it and is producing right at 575 hp at the crank, yet no issues with the SD system.

Oh, and I can easily put whatever size throttle body on it I want to support up to 2500 hp - at least that's what a buddy of mine is getting out of his twin-turbo Ford 351w setup (stroked) and running as well an Accel DFI Gen 7 system.

 

I didnt say it wouldnt handle large cams, it doesnt do well with certain cams. You lose some tunability with MAP on a large cam engine. It can be done but its definately more picky to the tune. I"m refering to a GM SD system, but others may have similar issues with large cams. A good cam in say a 383 that will make well over 500 crank hp and turn over 6500 rpm peak power may idle at 70-80 kpa, and your tune will only have 70-100 to work with or worse, 80 to 100. MAF seems to have more adjustablility in my opinion. I"m just fairly new to the SD thing but seen alot of issues with large cam idle here on TGO with factory SD setups. Trick seems to give it alot of timing, force open loop and tune from there

But to clarify, what is your setup and what is your cam? What does it idle at MAP KPA wise?

 

I'm using DynamicEFI EBL system, on a Ramjet. Works very well. It is based on a GM ECM. Lots of support here too. Dean.

 

Engine is a 351c (Ford) stroked to 408, cam is 112 LCA, .631 exh/.621 int with 302/298 duration. KPa at idle is 66 (900 rpm), but what I do is use the "scaled MAP" feature of my software to give me lots of resolution between 60 and 102 KPa, then I also scale the RPM range, giving me the most resolution around idle RPM, launch RPM, and then finally more range from 5k-7k RPM for WOT pulls.

Using Accel Gen 7 EFI with 1350cfm throttle body and 48# injectors (but could go down to 40# injectors as I'm only running these at about 72% at WOT).

 

Yeah thats about right for that cam. Its not "huge" by any means for a 408 but definately healthy. Lift is great tho that a solid roller?. My 401 right now has hyd. roller 292/292 233/233 on a 112, .564" lift and seems to idle fairly easily at around 900 ish and 55 KPA or so. My 383 last year would be abit tougher to get idle right with its 286/306 230/245 .603/.613 on a 109. Its got much more overlap to deal with. Thats the hardest part to tune I think. Doable with effort but not as easy as MAF atleast when talking about GM ecms from factory.

The accel gen 7 stuff seems to be pretty good. My buddy runs a 454 big block on gen 7 but it needs tuned. its pretty rich and he doesnt want to mess with it.

 

He should be able to get a tune from Accel for his setup. I did, and only had a hour of tuning to the base fuel map after that and was done. Have him email Accel support and tell them engine stats (CI, HP, and injector size) and they'll likely have something very close...especially on the Chevy side, not so strange as my Ford stuff...