Torque BS Filter ``

[DICK BREWSTER]

From: Seth Allen <n9540517 at cc.wwu.edu>
Date: Fri, 21 Feb 1997 18:56:24 -0800 (PST)
>Subject: Re: Torque BS Filter ``

>...

>Okay, first the relationship is HP= Torque(in lb-ft)x RPM/5252.
>Next, about the BS meter.  If you don't believe that a 
>turbocharged 454 cubic inch V8 running in excess of one 
>atmosphere of boost, on propane, can't make more than 800 lb-ft 
>of torque, then I would like to hear why. Secondly, the torque 
>figure was at a low rpm, and with the extremely low valve lift, 
>the rpm range was severly restricted.  I cannot tell you what 
>the hp was at 5252 rpm, but that was above the ordinary engine 
>speed for the application.


With low valve lift and a moderate boost like you had, you did a 
lot of work on the air that you can't get back (charge heating).  
Was there some benefit to the low valve lift that made the extra 
pumping effort worthwhile?


>Seth Allen

800 ft-lb out of a turbo charged 454 cubic inch 4 stroke Otto 
cycle isn't out of the ordinary, But I said the BS meter only 
works on naturally aspirated four stroke Otto cycle engines.  
With a turbo, it's obviously another game, as it is with a 2 
stroke which can make more torque/cubic inch than a 4 stroke.  It 
also doesn't apply to naturally aspirated diesels, the don't make 
as much torque per cubic inch as a naturally aspirated 4 stroke 
Otto cycle.  Any claims of over about .85 ft-lb / cubic inch for 
a naturally aspirated four stroke diesel should set off the 
alarm.

Ob. DIY EFI Content:

This is all getting a bit off topic, except for the fact that 
knowing approximately what you can expect to get out of an engine 
after you get done modifying it can help you do your initial 
design work.  Once a person understands that you are pretty much 
limited to about 100%-110% volumetric efficiency for a naturally 
aspirated street engine, he can get on with sizing a fuel 
injection system correctly, instead of sizing it for the 2 
ft-lb/cubic inch he wishes he could get.