[Gmecm] TBI - TPI swap ??

[Nick Cooper]

Along these same lines, has anyone got any experience with the LT1 &/or
Ramjet intakes as compared to the TPI? I'm wondering if either of these
intakes makes much better top end power on a 383?

Nick

 -----Original Message-----
From: 	gmecm-bounces at diy-efi.org [mailto:gmecm-bounces at diy-efi.org]  On
Behalf Of Rick McLeod
Sent:	Monday, August 28, 2006 1:55 PM
To:	gmecm at diy-efi.org
Subject:	Re: Re: [Gmecm] TBI - TPI  swap ??

I just lent out my authoratative book on SBC's, by Lingenfelter, but I seem
to recall he dub'ded the TPI as a tow truck motor, meaning it made gobs of
torque off idle to the limit of the runners at just under 4000, and from my
seat of the pants w/ the 3 I've tuned, that is absolutely true. My Vette
will run down the road at 1100 RPM quite happy, will pull hills, and all,
cruises very nicely at 70+ knocking down 33+ MPG, since it's sitting right
smak on the bottom 1/3 of the toruqe curve, it still pulls strong without
having to downshift. I've not been in a TBI car that does that, but the
TBI's gennerally will rev higher so are better on track either stratght or
twisty. But stoplight to stoplight, give me a well tuned TPI and I'll twist
axles with it.


----- Original Message ----
From: Per Lonnborg <perlon at passagen.se>
To: gmecm at diy-efi.org
Sent: Monday, August 28, 2006 12:11:04 PM
Subject: Re: Re: [Gmecm] TBI - TPI swap ??


dennysweet at charter.net wrote at 2006-aug-22 05:20:

>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.

Chris Reynolds [red83brick at yahoo.com] wrote at 2006-aug-22 17:01:

>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.

Hello!

I just want to ask again if the two statements above is "true" about TPI vs.
TBI.
I know (and probably everyone else too) that a stock TPI will lose its power
above 5500 rpm due to intake runner diameter and lenght,
thats a fact.

But I was quite surprised that TPI also would lose torque in the lower rpm,
compared to a TBI system?
Arent those long, thin runners perfect for low- and middle rpm?

/Per
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