tbi tuning

[gmclowsierra]

does anyone know where i can get a tune for a tbi setup? looking at converting my 85 to tbi. 355ci .477-480 lift cam. 10.5-1 compression. thanks for the help. JOE

[LEEVON]

www.tbichips.com

http://www.cfm-tech.com

http://www.fullsizechevy.com/forums/...obd-i-ecm-pcm/

[crossy's son]

The guys on FSC told me to get a labtop and $200 worth of equipment and you can sit on your la-z boy and burn your own custom chips all day long. Theres some experienced really good TBI tuners on fullsizechevy.com

But there 73-87 forum over there is not as good as this one . i love this forum

[chevy2ss]

go check out thirdgen.org

[pig rig]

talk with local guys that have put ECM controld engines in hot rods and find out who's doing theirs and talk with dyno shops and you'll find more and more one name will come up thats how I found the guy thats done mine and will keep doing them

[79blazer]

The guys that program custom "PROM" chips can get it pretty close to your engine specs, but further tweaking can be done by data logging while driving. Then changes need to be done on another prom. It can be a trial and error process.

[D13]

Remember TBI's usually are MAP sensor driven and not fond of big cams and low idles. But boy are they nice on cold start!

[rfmaster]

Larger cams (within reason) can be dealt through altering programmed idle parameters. Generally speaking, for a stock speed density system used in 87+ trucks keep cam LSA above 112 deg, with 114 deg being ideal while keeping duration at 0.050 below 214 degrees. Trucks need low RPM torque (to move the weight) and higher duration cams generally produce HP at higher RPMs.
The problem is not just the cam change but that the overall volumetric efficiency of the engine is effected - new cam usually goes together with different heads (porting, aftermarket, etc), free flowing exhaust, alternative intake, etc. The only way to deal with these changes is to tune your combination yourself. There is a learning curve involved, but results are worth every penny.

//RF

[chevymotocross]

Everything here was well said. I have heard all good reviews for tbichips.com. Whatever you do, don't buy a "generic" chip that you can buy from a mail order (jegs, summit). You need a chip burned for YOUR application. One chip can't possibly be fit for every vehicle out there.

I have an 87 with a high mileage 305. I have since added true dual exhaust, k&n drop in filter, injector pod spacer, and tbi spacer. The exhaust and spacer are what made the most noticeable increase in torque. I think I need to add an adjustable fuel regulator though to bump up the pressure and a chip.

I'd love to add a cam and heads next since the truck seems to have good torque/throttle response but falls flat on its face in the high rpm.

[rfmaster]

Originally Posted by chevymotocross

I have an 87 with a high mileage 305. I have since added true dual exhaust, k&n drop in filter, injector pod spacer, and tbi spacer. The exhaust and spacer are what made the most noticeable increase in torque. I think I need to add an adjustable fuel regulator though to bump up the pressure and a chip.

I'd love to add a cam and heads next since the truck seems to have good torque/throttle response but falls flat on its face in the high rpm.

The high millage 305 (LO3) have served you very well, but it is an induction limited engine by design! The factory cam was specifically deigned for low RPM performance where this engine developed its torque. Consider this, LO3 (TBI) used in many Camaros used a camshaft with I/E 0.351/0.386" lift and duration I/E 180/196 deg. These engines were rated at 170HP@4000RPM and 255ft-lb/2400RPM. Truck 305 had similar factory ratings and used swirl head design which limits high RPM potential. It is possible (and have accomplished by many) to improve on these numbers with a hotter cam, better heads and exhaust, etc.
Finally, EPROM tuning will extract the overall performance that otherwise can not be realized by leaving stock factory EPROM parameters or by simply relaying on mail order tune. To perform your own tuning requires investment of time and equipment.

//RF

[Hoods69BadBowTie]

Originally Posted by D13

Remember TBI's usually are MAP sensor driven and not fond of big cams and low idles. But boy are they nice on cold start!

x2 I know you can get around and get a good cam still though. Its all a trial and error process and its got to be tuned for your rig so spend some money and time on it and you will be happy

[gmclowsierra]

here is my compination 355, 10.5 compression, vortec heads, comp cams x treme energy 262 cam. .477-.480 lift cam 112 degress of seperation. edelbrock intake,flowtech headers with 2 1/2 exhaust down to 2 c hamber flowmasters. also what is lsa in the above response? thanks for all the great info. JOE

[rfmaster]

Originally Posted by gmclowsierra

here is my compination 355, 10.5 compression, vortec heads, comp cams x treme energy 262 cam. .477-.480 lift cam 112 degress of seperation. edelbrock intake,flowtech headers with 2 1/2 exhaust down to 2 c hamber flowmasters. also what is lsa in the above response? thanks for all the great info. JOE

LSA = Lobe Separation Angle (x-treme energy cam has 112 or 114 degrees depending on a grind #) That cam is hot cam, but should work well with your 355 combo.

Vortec heads will not require as much timing as your original heads and with all other speed goodies that you have no stock bin (EPROM contents) will run your engine properly. Did you update Vortec heads for higher lift????

One point of reference for bin files is Moates.net in the 1227747 $42 section. There are several posted bins there that were developed to run engine combos very similar to yours. With enough fuel and proper tune your combo should be in 300+ HP range. Expect to idle around 700 RPM with a hint of lope. My advise - learn how to burn your own chips or get EBL board from Dynamic EFI which allows real time changes - no chips required. http://www.dynamicefi.com/
EBL makes tuning a much simpler task (I have EBL flash in my C20) well worth it.

//RF