[Gmecm] TBI - TPI swap ??

[Chris Reynolds]

The problem with TPI is the runners are setup to resonate at around 3,000 RPM, which greatly improves torque there.   The throttle response will be slightly better than the TBI setup, but you will lose a ton of low-speed torque, which is everything in a heavy suburban.   
   
  I put TPI on a modified TBI 305 in a fullsize van that I use for pulling heavy trailers.  It spends 90% of its time between 2,500 and 3,000 rpm in 3rd gear doing 60-70 MPH with brief runs to 4,500 in 2nd gear climbing some good grades.    Works well enough for me, but the torque loss definately shows up with an unloaded van cruising in overdrive.     
   
   
  I would try to find a later model CSFI Vortec 350 to use the harness, PCM, etc.  It is already PFI, uses a MAF sensor, and is Sequential Fuel Injection.  I am also using a 1997 SFI Vortec PCM to run the TPI and 4L60E that is in this 1994 G20.   Made the swap so much easier than using a piggy back ecm and harness.    I just pulled the harness from the 1997 G1500 Express, the underhood PCM, the distributer, the ignition module, the coil, and swapped it over to the TPI.   I ran it on the stock 305 Vortec PCM for a while and it ran great.  Wanting more, I bought a software package that allows me to reprogram the PCM with my laptop, it runs alot better now.   But it still won't make torque like my TBI setup did.

?ke Georgsson <papegoj at telia.com> wrote:
  
> The TBI I run now outperformed the TPI by a large margin. Tuned Port 
> Injection is pretty impressive to look at but you cant get a lot of 
> power after 5500 rpm and you lose a great amount of torque on the 
> lower end of the RPM scale.
> So if your not looking for a system to perform well then use the TPI 
> unit. However if you want a injection system for offroad,hill climbing 
> or playing in the Mud stick with the TBI.
> Just my 2 cents
> Denny _______________________________________________
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Hi denny no problems the cam i use dosent know high rpms 
Basic Operating RPM Range: 500-3,800 RPM so that wouldent be a problem 
:-)
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