X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 2 [X] Return-Path: Received: from imo-m26.mx.aol.com ([64.12.137.7] verified) by logan.com (CommuniGate Pro SMTP 5.1.8) with ESMTP id 2020744 for flyrotary@lancaironline.net; Wed, 02 May 2007 01:59:18 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.12.137.7; envelope-from=Lehanover@aol.com Received: from Lehanover@aol.com by imo-m26.mx.aol.com (mail_out_v38_r9.2.) id q.cb0.10e5431c (60470) for ; Wed, 2 May 2007 01:58:12 -0400 (EDT) Received: from WEBMAIL-MC01 (webmail-mc01.webmail.aol.com [64.12.170.78]) by ciaaol-m02.mx.aol.com (v115.11) with ESMTP id MAILCIAAOLM023-ec3646382874245; Wed, 02 May 2007 01:58:12 -0400 References: To: flyrotary@lancaironline.net Subject: Re: [FlyRotary] Re: Throttle body size/ other "Paul" issues Date: Wed, 02 May 2007 01:58:11 -0400 In-Reply-To: X-MB-Message-Source: WebUI MIME-Version: 1.0 From: lehanover@aol.com X-MB-Message-Type: User Content-Type: multipart/alternative; boundary="--------MB_8C95A96003DDCCE_180C_6063_WEBMAIL-MC01.sysops.aol.com" X-Mailer: AOL WebMail 25698 Received: from 68.164.239.202 by WEBMAIL-MC01.sysops.aol.com (64.12.170.78) with HTTP (WebMailUI); Wed, 02 May 2007 01:58:11 -0400 Message-Id: <8C95A96003DDCCE-180C-3616@WEBMAIL-MC01.sysops.aol.com> X-AOL-IP: 64.12.170.78 X-Spam-Flag: NO ----------MB_8C95A96003DDCCE_180C_6063_WEBMAIL-MC01.sysops.aol.com Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii" On further review, TB size should have no affect on throttle response at all in an ijected system. In our carbed engines, rapid throttle opening drops manifold pressure to ambiant and flow through the booster venturi is not adequate to match the fuel flow to the throttle position and the engine falls on its face for lack of fuel. Thus the accellerator pump and jet system, which pees a long stream of fuel into the hole while the engine winds up enough revs (and air flow) to engage the boosters and get a fuel mist pouring into the carb. No such drama should be required in the injected engine. Should the TB open in less than X amount of time could not the injectors closest to the engine stand wide open for one or two revolutions, or cycles? Or even just some period of time longer than normal? So, it should not matter at all how big the TB is, as it is not even required until you want to slow or shut down the engine. If there is a butterfly in the inlet tract, the tuned length is usually figured from that, and not the total length as from the opening into the air filter or inlet bell. Notice the slide valve throttles on big time race engines. No affect on the tuned length. That throttle shaft and butterfly screws up the tune, and shortens the tuned length. On the old Formula Continental engines, stock 1600CC VW water cooled engines with the heads and decks shaved to give huge compression with stock parts, the injection was free. So what did the smart people use for injection? High pressure mechanical with high pop pressure injectors, that shot a nasty looking stream of fuel, not a nice fog of fuel at all. The injectors were mounted in the center of long bell shapes, and that fast moving stream of fuel was part of an ejector system that was used to boost airflow to the tune (pun) of 175 HP from a 54 HP VW Rabbit engine. So the bigger the TB the less it should affect the tuned length, and conversly the smaller the TB the more it should affect the tuned length. For a reference the difference between carbed and injected engines with a restrictor in the injected system the same size as the choke in the carbed engine as 5 to 8 HP. This is mostly the loss of the booster venturi in the center of the hole. The improvement in a carbed engine between 36MM and 38MM chokes is about 5 HP. Per Daryl Drummond. Race engine builder. Is this fun to think about or what? Lynn E.Hanover ----- Original Message ----- From: wrjjrs@aol.com To: Rotary motors in aircraft Sent: Tuesday, May 01, 2007 12:27 PM Subject: [FlyRotary] Re: Throttle body size/ other "Paul" issues Interesting Lynn, For the comparison that is 2,035 square mm inlet area. Assuming the bigger 13B could use 1/3 More inlet area the total would be 2,646 square mm. The inlet area of the 65 mm throttle body is 3,318 square mm. Seems like a 65 mm TB would be more than up to the task. A 60 mm TB is 2,827 square mm for reference. Plenty big Buly Bill Jepson -----Original Message----- From: lehanover@aol.com To: flyrotary@lancaironline.net Sent: Tue, 1 May 2007 9:08 AM Subject: [FlyRotary] Re: Throttle body size/ other "Paul" issues Two 36MM chokes is enough for 244.8 HP at 9,400 RPM, and About 176 HP at 7,000 RPM. I am in California and the dyno sheet is in Hebron Ohio. But I can quote it when I get back if it would help anyone. Lynn E. Hanover AOL.com. ________________________________________________________________________ AOL now offers free email to everyone. Find out more about what's free from AOL at AOL.com. ----------MB_8C95A96003DDCCE_180C_6063_WEBMAIL-MC01.sysops.aol.com Content-Transfer-Encoding: 7bit Content-Type: text/html; charset="us-ascii"
On further review,

TB size should have no affect on throttle response at all in an ijected system.

In our carbed engines, rapid throttle opening drops manifold pressure to ambiant and flow through the booster venturi is not adequate to match the fuel flow to the throttle position and the engine falls on its face for lack of fuel. Thus the accellerator pump and jet system, which pees a long stream of fuel into the hole while the engine winds up enough revs (and air flow) to engage the boosters and get a fuel mist pouring into the carb.

No such drama should be required in the injected engine. Should the TB open in less than X amount of time could not the injectors closest to the engine stand wide open for one or two revolutions, or cycles? Or even just some period of time longer than normal?

So, it should not matter at all how big the TB is, as it is not even required until you want to slow or shut down the engine. If there is a butterfly in the inlet tract, the tuned length is usually figured from that, and not the total length as from the opening into the air filter or inlet bell. Notice the slide valve throttles on big time race engines. No affect on the tuned length. That throttle shaft and butterfly screws up the tune, and shortens the tuned length.

On the old Formula Continental engines, stock 1600CC VW water cooled engines with the heads and decks shaved to give huge compression with stock parts, the injection was free. So what did the smart people use for injection? High pressure mechanical with high pop pressure injectors, that shot a nasty looking stream of fuel, not a nice fog of fuel at all. The injectors were mounted in the center of long bell shapes, and that fast moving stream  of fuel was part of an ejector system that was used to boost airflow to the tune (pun) of 175 HP from a 54 HP VW Rabbit engine.

So the bigger the TB the less it should affect the tuned length, and conversly the smaller the TB the more it should affect the tuned length.

For a reference the difference between carbed and  injected engines with a restrictor in the injected system the same size as the choke in the carbed engine as 5 to 8 HP. This is mostly the loss of the booster venturi in the center of the hole.

The improvement in a carbed engine between 36MM and 38MM chokes is about 5 HP. Per Daryl Drummond. Race engine builder.

Is this fun to think about or what?

Lynn E.Hanover
 
 

 
----- Original Message -----
Sent: Tuesday, May 01, 2007 12:27 PM
Subject: [FlyRotary] Re: Throttle body size/ other "Paul" issues

Interesting Lynn,
For the comparison that is 2,035 square mm inlet area. Assuming the bigger 13B could use 1/3 More inlet area the total would be 2,646 square mm. The inlet area of the 65 mm  throttle body is 3,318 square mm. Seems like a 65 mm TB would be more than up to the task. A 60 mm TB is 2,827 square mm for reference. Plenty big Buly
Bill Jepson
 
 
-----Original Message-----
From: lehanover@aol.com
To: flyrotary@lancaironline.net
Sent: Tue, 1 May 2007 9:08 AM
Subject: [FlyRotary] Re: Throttle body size/ other "Paul" issues

Two 36MM chokes is enough for 244.8 HP at 9,400 RPM, and About 176 HP at 7,000 RPM. I am in California and the dyno sheet is in Hebron Ohio. But I can quote it when I get back if it would help anyone.

Lynn E. Hanover
 
 

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