[Gmecm] TPI vs TBI & others

[Beau Blankenship]

Some folks here may remember, I just made that switch from TBI on a
Performer intake to basically stock TPI with LT1 injectors. The TBI was the
Pro-Jection TB (2" bores) run by a GM '7747.  I can honestly say that the
TBI had noticeably more power in the higher RPMs. Highway driving was really
fun at times. BUT, it was kind of sluggish around town and had a hell of a
time holding its speed on the highway with the boat hooked up (unless, of
course, the speed was 90mph). Then came a motor swap. Basically the same
350, bored, flat-top pistons, small-runner small-valve heads, etc. The cams
were a little different (TBI motor had a large 218/226 cam and the TPI got a
206/214). The TPI motor has plenty of low-end torque to pull the boat at any
highway speed in OD. But those long steep hills on the way to the Brady
Mountain Marina require a very generous right foot in 2nd gear. I would
never trade the TPI for another TBI in my daily driver. If I were building a
racecar, I would probably not use the TPI due to its lack of high-rpm power.
But for my Blazer, I have to agree with William. The TPI has plenty of low
RPM torque and only falls short of the TBI over 4000-4500 RPM "in my
experience." I tend to not trust manufacturer's dyno tests and claims,
because their engine is not what is in my truck. Both types of GM EFI have
their benefits, but I would NOT say that the TPI has any problem with low
RPM torque.

Beau Blankenship

-----Original Message-----
From: gmecm-bounces at diy-efi.org [mailto:gmecm-bounces at diy-efi.org] On Behalf
Of Chris Reynolds
Sent: Wednesday, August 30, 2006 8:53 PM
To: gmecm at diy-efi.org
Subject: Re: [Gmecm] TPI vs TBI & others

Dyno test on 7 different swaps.  Dual plane manifolds give more torque down
between idle-2,200 rpm than the TPI setup, then out pull it again over
4,500.   

William Lucke <william.lucke at highspeedlink.net> wrote:  My experience with
TPI is that it has tremendous low RPM torque. I'm 
wondering evidence people who claim otherwise are basing their claims on...

Also, someone asked how TPI compared to a couple of other manifolds. Due 
to a bug in my email program (Thunderbird), I can't reply to that 
message. From what I've heard, the Holley Stealth Ram (HSR) is currently 
the hot setup for replacing a TPI with something more high RPM oriented, 
but not as much so as a Mini-Ram.


Will
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