aftermarket EFI tuning

[Blown353]

I'm with Jody here; if you run single-plane, go with an elbow and a monoblade to get the hat out of the picture. You can run whatever monoblade TB you want, and I believe Wilson makes the 90 degree elbows. A 75mm monoblade would be more than enough. If you go too big on a monoblade, off-idle throttle response becomes quite touchy as just a small move on that big butterfly results in a HUGE amount of additional airflow. It can also make tuning the enrichment parameters tricky as you can cause massive and rapid vacuum swings with just a tiny bit of movement; it will take some tweaking of the AE vs. MAP rate and AE vs. TPS rate to make things work smoothly, while a 4 hole TB will be more forgiving as it takes a greater throttle input to cause a vacuum change on the same magnitude.

The monoblade throttle bodies are also cheaper and simpler than the 4-hole holley-style throttle bodies; less shaft seals to leak, no progressive linkage and the associated wear points, etc. You'll be a bit more restricted on plumbing since the TB will point straight forward, but you should be able to work around that.

Another recommendation for Rob @ Force EFI here. I bought all my FAST stuff through him and he custom did a wiring harness for me; nice guy, fair prices, and nice work.

Troy

[binkt]

Originally Posted by camcojb

Thnaks for the info Jim. I have never tuned the Holley system, but have heard very good things about it.

Jody

I am using the Holly StealthRam TPI and commander 950 pro and have found it to get more out of my sbc than any previous combination of carburetor I used. It takes some basic computer savvy and practice to tune. Holly phone Tech Support is superb. I recommend the wide band oxygen sensor option for ease of use and better control. My rear wheel horsepower increased by 75 HP with the optimum tuning afforded by the system.

[slow4dr]

AEM will have a flying lead harness for custom adaptation available very soon for their EMS. The AEM EMS is just as capable as the high priced Motec systems with pricing equal to or less than FAST or BS3. The programming is very advanced and not for the computer challenged but is well worth the outcome once properly tuned. They also have a VERY active user forum for tech support.

www.AEMPOWER.com

[GregWeld]

I've been "playing" with the Accel Gen VII on my 427 small block chevy for most of 2 years now. I had the earlier version on a 502 in my 67 Vette and was VERY unhappy with it - but the Gen VII is actually very tunable and I think "easier" than "we" make it out to be. Really -- this is little different than tuning a carb and curving a distributor. The motor parameters are put in - knowing your cam and head facts are critical here... and the Gen VII will build a VE table for you... which you can then fine tune. I frankly had the most trouble building a proper A:F table! You talk to one guy and he tells you idle should be around 14.7:1 -- so you try to tune this ala a "new" car (which run these very lean AF's) and find the thing just won't run ----- so like most tuning --- you resort to what the motor wants. My 427 - Canfield headed - Comp Cams 288 wants a really FAT idle AF... and then I adjust the VE to read (taking the O2 sensor off line) the programed AF... The Accel Gen VII with a wide band O2 sensor also has an "auto calc" button.... so I have a buddy drive -- and I tune various areas using the auto calc and then smooth the areas around these cells. When I see very little O2 "input" - i.e., when the O2 is adding or subtracting less than about 2 or 3% then this is "good"....

Tuning the "curve" is also pretty straight forward -- starting at 18 degrees intial -- you can then add timing up to your total timing baselines... My car runs best at idle with 20 degrees (900 RPM - low vacuum signal) - rising very quickly to total 36.... during the drive and tune session -- I work on the high vacuum light throttle cells -- going lean as much as 15:1 and 45 degrees timing... not much different than a distributor with vacuum advance....

Trust me -- I've tried real hard to make tuning this thing hard -- and finally after all this time -- have realized I made it overly complicated -- and changed too many parameters too soon.... when it really comes down to AF (jetting) and timing (curving the distributor) - the rest of the stuff is selectable for fans - AC - idle air control (I plug the air port on the TB and set the idle so that the IAC motor is doing basically nothing at idle).... and then you just have to remember that for every "CHANGE" you have to reset the TPS (throttle position sensor) as this piece works on voltage readings for a linear throttle response. When you raise or lower the set screws on the linkage - you've changed the voltage reading at the TPS... and the computer has to be told to reset... THOSE are the learning curve issues that take time to get --- and ALSO remembering to SAVE the program to a file! Keeping your "old" one so if you mess it up - you just reload and start over....

I AGREE WITH ACCEL TECH SUPPORT --- SAYING THEY SUCK IS A MAJOR UNDERSTATEMENT... they're non-existant. You buy ACCEL -- you're on your own! But there's plenty of people out there that can help. All in all -- it's fun tuning this way.