Valve Train noise

[John Hess]

The original post I was taking exception to was from a person who 
intimated that if any more power could be obtained by seemingly minor 
modifications to the intake, that GM would have done it.  Everything I 
have said since refutes that.  That is the ONLY point I have to make. 
 As for homework, that is the reason I started all over on the engine 
instead of "tacking" things on.


----------
From:  peter paul fenske[SMTP:pfenske at direct.ca]
Sent:  Monday, January 20, 1997 12:05 AM
To:  diy_efi at coulomb.eng.ohio-state.edu
Subject:  RE: Valve Train noise

Hi Gang

You guys should do a bit of homework.
The best writeup of data and airflow specs I saw was in High-Tech 
Magazine
in an article"altered profiles" by Ray Bohacz. Lots of airflow and
horsepower calcs. The gist is the max HP assuming you have
blueprinted your engine is 329 gross HP with everthing stock.
That would be your limitation. With tricks and the stock L98 roller
cam with 1.6 rockers this jumps to about 373 HP.

With the torgue curve this means low 13s high 12s but that is it 
folks
You wanna go faster you spends more money.

As for general info on ecms injectors ect TPIS has a great web page
with a good writeup on ecms pcms whatever. Either printout their page
or get their book.

So follow the advice by the sages and use the system for what it is 
given.

CUall: peter


At 10:31 AM 1/20/97 -0600, you wrote:
>What do the torque curves look like after doing these mods? Since the 
TPI
>system is designed to give the maximum tuned effect at a certian 
point, what
>do you really gain?  Bench flow numbers don't give me a rise. Some 
TPI
>system don't even use a MAF. Do they have a _significant_ power 
advantage
>over the MAF equiped tpi? Convince me to butcher my $300 MAF.
>
>Thanks man
>GMD
>
>At 09:25 AM 1/20/97 -0600, you wrote:
>>I would rather not quote my source;  however, if one looks at the 
flow
>>characteristics of the stock TPI one finds that it flows 
approximately
>>435 CFM.  Making slight mods as follows causes significant changes 
to
>>this.
>>Cut the screens off the MAF increases the flow to 512 CFM
>>Install a throttle body air foil increases the flow further to about 
>>530 CFM (Still not in the realm of what one would consider for even 
a
>>moderate performance 350).
>>Opening up the filter cover and putting a K&N filter in gets us into 
>>the 560 CFM range.
>>Modifying the MAF (Cutting and polishing the heat sink inside) gets 
us
>>up to about 585
>>As you can see, there is room for much improvement without ever
>>getting out of the air intake.
>>
>>The MAF, itself flows about 529 CFM stock.  Taking the screens out
>>gets it up to over 700 CFM.  Modifying the heat sink and cleaning up 
>>the inside gets it up to about 750 CFM.
>>
>>Note that all this data is corrected to 20.4 inches of water (What
>>Holley rates their carburetors at).
>>
>>Since this is a "dry" flow system (no fuel in the air stream), the
>>equivalent to a carbureted engine is about 650 CFM.  NOW we are in 
the
>>realm of a solid 350.  Further improvements may now be realized by
>>mods to the throttle body, plenum, runners, and base.
>>
>>
>>----------
>>From:  Scot Sealander[SMTP:Sealand at clarityconnect.com]
>>Sent:  Saturday, January 18, 1997 7:47 PM
>>To:  diy_efi at coulomb.eng.ohio-state.edu
>>Subject:  Re: Valve Train noise
>>
>>John Hess wrote:
>>
>>> The original TPI was designed for the 305 engine
>>> and is woefully inadequate for even a mildly built 350.
>>
>>Do you have a source for this?  How do you know it was designed for 
>>the 305,
>>and not the 350?
>>
>>
>>> To state that these parts are fraudulent or that the people
>>> who sell them are liars is irresponsible and/or stupid..
>>
>>Maybe not.  Just what does that "air foil" do anyway... ;-)  As far 
as
>>aftermarket PROMs, the three I have looked at did not do much. 
 Delay
>>TCC lock
>>up by several mph, maybe reduce the ESC attack rate (makes sure of 
the
>>need
>>for 93 octane!)  Change fan turn on temp.... One completely zero'd
>>every EGR
>>location..... Basically no ignition or fuel changes.  Not a lot for 
>>the 150
>>bucks or so they charge!  That is close to fraudulent in my book, 
and
>>points
>>out that GM tunes them pretty well from the factory.
>>
>>I am sure that some of the aftermarket is great stuff, but the
>>consumer must
>>understand what he is buying.  The TPI is a great low/mid RPM intake 
>>system,
>>and that may not be clear to all consumers.  So if you make changes 
to
>>your
>>350 that increase airflow requirements at higher RPMs, the TPI will 
>>not work
>>well for you.
>>
>>Scot Sealander    Sealand at clarityconnect.com
>>
>>
>>
>>
>>
>
>