Cams vs. EFI

[Doober]

Can anyone elaborate on the effect of a cam profile and what will be needed to be compatible with a stock EFI setup (TBI is what I'm looking at mainly here). I won't always be running the 350 I have in the 'Bu, I plan to eventually go with an LS motor. My question lies with taking off the carbed intake that's on there and bolting on a TBI intake for Vortec heads, and dropping it in my '92 Sierra. I would probably upgrade the throttle body as well. I know everything will bolt in and hook up, but I don't know if it will make the stock computer freak out. I know it will have to have a different tune on it, I have a feeling I would be going with a setup from an online site that I can't find right now (maybe someone can help me here, it replaces part of the original TBI computer and you can tune it via laptop and datalog with it as well I believe).

Any takers?

 

[Doober]

Also, another thought I had was maybe just giving a shot at putting TBI onto the motor when I swap it into the '78. It's getting a new tank for a TBI Monte, and all new stainless lines set up for TBI, so it would be a swap-in deal so long as I got the computer, etc. out of another Monte.

 

[StreetBu]

If your sticking with a stock computer and tune, you can only jump about two cam sizes up without messing things up. Any more than that and you need a custom chip burnt.

 

[Doober]

A custom tune doesn't make me nervous I'm still trying to remember the company that offers a kit to convert a stock TBI/TPI computer to a flashable setup.

 

[Doober]

Ah-HA!

http://www.dynamicefi.com/

 

[big-angry-hillbilly]

You can run pretty much as big as a camshaft as you like anymore, there are some guys out there that do some pretty awesome tunes for some pretty radical camshafts.

LE's cams for the LT1 engines are VERY VERY aggressive - and the tuners can fix 'em up pretty good.

I'm right beside Detroit if you need any help.

 

[injected]

The thing i learned is that you can run bigger tan 215*degrees with stock cumputor even with a chip ! Dont even try to run more than 9 to 1 compression or get a costom chip ! if your cam gives less than 15 inches at idle the map wont pic up and i will be pig rich ! Hope it helped

 

[Doober]

My main thought was about the MAP sensor. I'm not sure what this one pulls, but it operates the stock brakes fine... I have a gauge for testing vacuum, should give it a look one day. I'd imagine I could at least get it to run, then go from there. If I go this route (which I very well may when I yank the motor out of the 'Bu for an LS) I don't anticipate too much trouble, I'd love to go with a kit from Dynamic EFI.

 

[injected]

Well if it opperate stock brake fine,you have a good chance you`l be allright. You can add a vaccum reserve,that would help ! Like i said if you are lower than 215* and you have 15 inches idle ,not more thant 9 to 1 you are close to fine ! Good luck

 

[liquidh8]

Doober, I have the EBL from dynamic EFI on my chevy wagon. It basically has the GMPP vortec 330 with 10.5:1 comp, and a comp XFI cam, 4 bolt mains, vortec heads, beehive springs, yadda yadda. With a factory computer (7747) it was UNDRIVEABLE! I started burning chips using the factory mask, ECU and modified bins. Went to the EBL since I have alot of upgrades, bigger throttle body, huge injectors, n2o, big cam, open element air cleaner, etc. Without the n2o, it runs 13.6 on street 17's and 4k race weight. Mileage is about 15 average. Using a 2004r and 3:73 rear gears.

Long short of it. If you go with too much duration/overlap on the cam, you get a vacuum signal that is too low and erratic. It screws the MAP all up and you can't tune the thing. Since your fueling tables at derrived from you MAP reading and RPM. The stock ECU and program dosen't like it, and it is almost impossible for a novice to tune. The idle would be messed up and part throttle would suck.

I would stab the cam you want, reasonable size, and get the EBL when you throw it in the truck. Get the BBC throttle body and the 90 pound injectors. I also run a vacuum adjustable fuel pressure regulator.

Use a wideband to tune you FI, the only way to go. I tune my turbo buick, and all my tbi/tpi chevys.

www.thirdgen.org has a wealth of knowledge there. User RBob is the creator of the EBL sold at www.dynamicefi.com


When you get to the swap, your more than welcome to give me a call and pick my brain since I did this swap already.