for the fuel injection gurus

[leadfoot067]

ok so i got a 91 chevy van with a tbi350....i want theTBI setup for my blazer...it has a built motor...heres the specs.350..030 over,flat tops,crane HMV278 cam,world products sr torquer heads,and a bowtie intake (like a performer RPM)... will this run with this TBI setup without a bunch of hassle?

 

[Sandman]

What are the exact specs on the cam? There is a rule of thumb on what the stock system can handle. I cant remember it off of the top of my head though. I did find it on Thirdgen.org once.

 

[blazerguy 90]

It will require a chip and some tunning to make it run right, but its possible.

 

[leadfoot067]

GOOD IDLE, DAILY USAGE, OFF ROAD, HIGHWAY TOWING, FUEL EFFICIENCY PLUS PERFORMANCE, 2600-3000 CRUISE RPM, 8.75 TO 10.0 COMPRESSION RATIO ADVISED. (50 STATE LEGAL, PRE-COMPUTER, C.A.R.B. E.O. D-225-21) BASIC RPM 2000-5000

DUR 216@50 and 454 lift

 

[thor]

Good rule of thumb is that the motor needs to pull 15" of vacuum at idle, in gear. If you're close enogh for it to run well in closed loop you can boost fuel pressure at the regulator to cover open loop until you get a chip burned.

What's the lobe separation on that cam? If it's 110 it may be iffy...

 

[ntaj*ep]

I was going to use something like this setup as well. Howell wanted $250 to burn a chip and said they recommended a larger 670cfm Holley t-body. But that the chip would most likely work for the time being......

 

[southernspeed]

Like Thor says, vaccum is the biggest problem. As long as you've got near that you should be ok. You can burn a chip to compensate, also Turbo City do an adjustable Map sensor to help compensate for low vaccum(did I spell that right? can never remember?? )

 

[dirtwarrior17]

Before you try to burn a chip or remap anything give the stock system a chance to prove itself...it takes a few days of driving around town for the computer to modify the map the best it can. I know a few guys that built 383's with over 300 hp and a shiit load of tq that run better off the stock comp than a hypertech chip. I know its not a custom chip but the stock prom can handle more than people give it credit for... i run WAY more mods than the stock prom is supposed to handle but it runs fine... just won't get your full hp potential without a chip. boosting fuel pressure is a good idea too. it doesn't seem like your asking for too much with that setup but bigger injectors or bigger tbi will definetly be needed to get peak power.

 

[mountain4x4]

If vacuum isn't within specs for the MAP sensor, the cheapest thing to do would be to get a Cam made for the TBI system. I just bought parts for a customers 383 tbi I'm building, and the guy selling me the parts has a 383 producing 300 + hp and has run it for 60K miles with just fuel pressure mods and 68 lb/hr injectors (stock is 55). Custom chips are a PITA unless you burn them yourself. Most people do not get the right programming the first time from custom chip makers, it may take a few tries to get something you are happy with in a custom chip. Play it safe and tune it with a wideband o2 setup as well.

 

[leadfoot067]

The Crane Site Doesnt Give Me Lobe Seperation...ill Check My Vacume At Idle And See...thanks

 

[dirtwarrior17]

If vacuum isn't within specs for the MAP sensor, the cheapest thing to do would be to get a Cam made for the TBI system. I just bought parts for a customers 383 tbi I'm building, and the guy selling me the parts has a 383 producing 300 + hp and has run it for 60K miles with just fuel pressure mods and 68 lb/hr injectors (stock is 55). Custom chips are a PITA unless you burn them yourself. Most people do not get the right programming the first time from custom chip makers, it may take a few tries to get something you are happy with in a custom chip. Play it safe and tune it with a wideband o2 setup as well.

best way to do it is to get it dynoed at a shop and they'll send the pulls to a company and have a custom chip made or tune it yourself with a wide band and a pocket programmer or prominator.

 

[mountain4x4]

best way to do it is to get it dynoed at a shop and they'll send the pulls to a company and have a custom chip made or tune it yourself with a wide band and a pocket programmer or prominator.

This may work, but you would also need to have a logger on the truck to map timing vs rpms and map sensor signal. Then you would also need to run the truck at various conditions to see whats happening under part throttle (closed loop) as well. If you do this at a Dyno before you ordered the chip, the motor may not even be close enough to test safely, especially at open loop, plus you would have to pay lot of $ for dyno time, put the new chip in, pay even more $ for dyno time, and repeat, maybe several times... you could easily have $500 into the chip and paying for time at the dyno, if everything goes well. Or you could purchase a wideband o2 setup and a datalogging setup (or download winaldl for free and use your laptop), buy an eprom burning device and the software to use it, or install a flash chip to replace the eprom, get the programming software, and have at it. Either way will cost LOTS of time and money, and pretty much requires a laptop.

OR... just buy a cam that will work with the computers stock programming and use bigger injectors / adjustable fpr and fine tune the fuel pressure, preferrably using a wb o2, but I tuned my 'Burban by feel and reading the plugs, 'cause I'm too poor to buy a wb o2 right now, but I will soon to tune the 383 I'm building...

If youre trying to make over 350 hp or so, you really should just get a Haltech standalone for $800, (they make one thats plug-and-play) and have full laptop programmability, and fuel injector drivers that are strong enough for the application as well. Or, better yet, get a TPI system w/MAF sensor.