Hey all, I have a 99 Tahoe, Old Body Style, and am wondering if anyone has ever done a TBI setup in the Vortec 350 with what I believe is multiport. I know for sure that dont have TBI so I am merely assuming its multiport, not direct port. But am wondering if anyone ever has added TBI to this setup, or is it even possible. Clearly I am a semi-newbie, but have been reading the forums and am just looking to boost the hp and torque a bit for towing purposes. Am hoping to do CAI and Exhaust soon, along with BB for the power, but was wondering about the TBI for extra fuel delivery. Speaking of Towing, anyone recommendations tranny upgrades? Vette servos, shift kits, torque convertors, trans swap, retune?
TBI with Multiport?
- Thread starter genesis
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TIM Z
DMAX Power
No, you cant add TBI ( throttle body injection) to your multiport setup.
You either have one or the other.
The Throttle body injection ( TBI) is used on chevy/gmc full size trucks from 1987-1995.
A TBI setup is basically a carburetor with 2 fuel injectors in it. It was a step in the right direction for driveability but not as powerful as a multiport injection system.
A Multiport system has one injector for each cylinder and it also has a " Throttlebody", which is mereley a valve or "flap" for letting air into the engine.
The air and fuel ae mixed together in each cylinder. VS the TBI where air and fuel are mixed together in the throttle body then having to travel thru the manifold then to each cylinder.
Multiport is the standard for fuel injection nowadays and way more effecient/powerful that TBI setups.
Hope this helps.
If you are staying with a stock motor dont waste time/money on larger throttle bodies/spacers /or Mass air flow sensors for multiport engines.
Get a CUSTOM tune and exhaust and cold air intake and you'l have a great running enine assuming everything is tuned up under the hood.
You either have one or the other.
The Throttle body injection ( TBI) is used on chevy/gmc full size trucks from 1987-1995.
A TBI setup is basically a carburetor with 2 fuel injectors in it. It was a step in the right direction for driveability but not as powerful as a multiport injection system.
A Multiport system has one injector for each cylinder and it also has a " Throttlebody", which is mereley a valve or "flap" for letting air into the engine.
The air and fuel ae mixed together in each cylinder. VS the TBI where air and fuel are mixed together in the throttle body then having to travel thru the manifold then to each cylinder.
Multiport is the standard for fuel injection nowadays and way more effecient/powerful that TBI setups.
Hope this helps.
If you are staying with a stock motor dont waste time/money on larger throttle bodies/spacers /or Mass air flow sensors for multiport engines.
Get a CUSTOM tune and exhaust and cold air intake and you'l have a great running enine assuming everything is tuned up under the hood.
992dr
Full Access Member
I know of someone who had a GM TBI Vortec manifold modified to MPFI.
He's a member of a couple other forums.
Another option is a Marine manifold.
You gotta love the spider mess GM developed. Although someone has designed an upgraded spider assembly with high output injectors instead of the stock 19lbers.
95TwinTT,
Your truck is insane. That motor is bad ass.
He's a member of a couple other forums.
Another option is a Marine manifold.
You gotta love the spider mess GM developed. Although someone has designed an upgraded spider assembly with high output injectors instead of the stock 19lbers.
95TwinTT,
Your truck is insane. That motor is bad ass.
It's been done.
Check out the last post, should point you in the right direction:
http://www.fullsizechevy.com/forums...ermarket-spider-mpfi-conversion-manifold.html
Simple CSFI to MPFI, also:
http://www.theautoshop.net/VortecMPFI.htm
Check out the last post, should point you in the right direction:
http://www.fullsizechevy.com/forums...ermarket-spider-mpfi-conversion-manifold.html
Simple CSFI to MPFI, also:
http://www.theautoshop.net/VortecMPFI.htm
Thanks I appreciate the input. The tahoe will remain mostly stock with the exception of the CAI, exhaust and tune. Am just looing at basic power upgrades for now as the engine has 220,000 on it. To answer the question on towing. I am usuallyp ullins aroung 2000lbs with it but just built an 8x7x24 foot long ice house that doubles as my hunting shac and that is right in at about 7000lbs. on long drives I get 6mpg. its usually about two hours pulling it. problem is, tranny likes to kick in and out of overdrive on every little hill. so I am hoping that these extra horsepower mods will help and any thing I can thinl of for a tranny. I asked about TBI cause I know that it can make tremendous amounts of torque when done right. so wat hoping there was a way to do both. Even if it was similar to a NO2 setup where the TBI only kicked in at a percentage of throttle.
Sounds like for your situation, a performance tune and leave it in drive, while towing a trailer is your best option. The injector system you have is capable of adding more fuel. From the factory they would never exceed 80% saturation, for size and duration.
Third gear or 1 to 1 has been recommended for towing for years. Turning a few hundred more rpm’s is good for the drive train. For many years, 3,000 rpm’s was normal for 60 mph. It is the move towards higher mileage that drives the industry lower rpm’s. By nature, gas engines tend to make their power at higher rpm’s. If it were a diesel, it would be different. Then again, we would not be having this discussion.
The transmission is also less likely to have problems in third versus fourth, for towing down the highway.
Lots of people ignore the obvious and concentrate on CAI’s and Headers, while not doing anything about cam and heads. The actual flow of air in the heads is the key to power.
Third gear or 1 to 1 has been recommended for towing for years. Turning a few hundred more rpm’s is good for the drive train. For many years, 3,000 rpm’s was normal for 60 mph. It is the move towards higher mileage that drives the industry lower rpm’s. By nature, gas engines tend to make their power at higher rpm’s. If it were a diesel, it would be different. Then again, we would not be having this discussion.
The transmission is also less likely to have problems in third versus fourth, for towing down the highway.
Lots of people ignore the obvious and concentrate on CAI’s and Headers, while not doing anything about cam and heads. The actual flow of air in the heads is the key to power.
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992dr
Full Access Member
Both are what I was talking about. I have inquiered with the company that did that manifold in the FSC forum and the total was $900 not including the Vortec manifold. You will need to find a TB for the application to. A lot of people go the Marine manifold route over the custom MPFI manifold for the cost factor and ease of installation.
95TwinTT,
What heads would you recommend for our motors? What other mods would you recommend for max power gains?
Here's a question.
Does the aluminum spacer make any difference in power?
This one.
http://www.streetandperformanceelectronics.com/vmax.htm
TIM Z
DMAX Power
I understand you now ,
You want to replace your Vortec manifold with an alum True multi port manifold right?
I thought you wanted to add a TBI throttle body to your Vortec manifold, my bad.
Heck for a grand you can get an edelbrock MPI system ready to go.
Holley also makes a stealth ram that is similar to the LT1 style intake.
Or get a GMPP ram Jet intake.
Curious to see how ya make out.
You want to replace your Vortec manifold with an alum True multi port manifold right?
I thought you wanted to add a TBI throttle body to your Vortec manifold, my bad.
Heck for a grand you can get an edelbrock MPI system ready to go.
Holley also makes a stealth ram that is similar to the LT1 style intake.
Or get a GMPP ram Jet intake.
Curious to see how ya make out.
992dr
Full Access Member
Scroll down to post 118, thats what I'm talkin about. It doesnt get any cleaner than that.
http://www.fullsizechevy.com/forums...market-spider-mpfi-conversion-manifold-6.html
The benefit of this manifold is everything stays in the stock location, so, you can keep your K&Nfipk or any other CAI and any SCer made for a Vortec 5.7 would bolt right up to it wih no mods. Another bonus, you keep all emissions provisions.
Here's the picture from FSC.
http://www.fullsizechevy.com/forums...market-spider-mpfi-conversion-manifold-6.html
The benefit of this manifold is everything stays in the stock location, so, you can keep your K&Nfipk or any other CAI and any SCer made for a Vortec 5.7 would bolt right up to it wih no mods. Another bonus, you keep all emissions provisions.
Here's the picture from FSC.
