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Search found 395 matches

by pcnsd
Tue Sep 14, 2021 10:11 pm
Forum: Engine Tech
Topic: Ram induction question
Replies: 11
Views: 643

Re: Ram induction question

if you look close to under the carbs there appears to be a pipe with rubber hoses clamped to it. If we call it a "common plenum" what is the purpose of it. Ive seen other engines with intake banks separated Then a tube connecting them back together. In the Helmholtz equations, doubling the cylinder...
by pcnsd
Mon Sep 13, 2021 12:21 am
Forum: Engine Tech
Topic: Ram induction question
Replies: 11
Views: 643

Re: Ram induction question

Much of what is written above is correct. I disagree on one aspect but it may be little more than how I define a particular word. (Harmonic) Every length is a tuned length at some RPM and wave number. The lower the wave number the more energy it contains. There are only pressure waves in intake and ...
by pcnsd
Sat Aug 21, 2021 3:08 pm
Forum: Engine Tech
Topic: 2.0L MZR header and exhaust length testing
Replies: 24
Views: 1002

Re: 2.0L MZR header and exhaust length testing

If you break Calvin's numbers out by CSA against horsepower, it actually scales to be about 38-40hp / square inch across the board. I noticed this about 7 years ago and posted it here, but like a lot of things, it went over most people's heads. I put his chart from Exhausting101 into a spreadsheet....
by pcnsd
Fri Jul 30, 2021 10:18 pm
Forum: Engine Tech
Topic: Header primary diameter for a small motorcycle engine
Replies: 31
Views: 2071

Re: Header primary diameter for a small motorcycle engine

However, my thoughts are that since the torque curve stays so flat up to 13000 rpm, this suggests that for a 9300 rpm limited engine we should make the pipes all significantly smaller diameter. Significantly smaller than the current “smallest that anyone has ever run” size that we tried yesterday. ...
by pcnsd
Tue Jun 08, 2021 8:40 pm
Forum: Engine Tech
Topic: Any Way To Get This Exhaust Down To 95 Decibels Or Lower Without Destroying Good Flow?
Replies: 27
Views: 1610

Re: Any Way To Get This Exhaust Down To 95 Decibels Or Lower Without Destroying Good Flow?

David, I'm not sure I understand the question or perhaps you misunderstood the end cap used. Closed end, end caps result in a reversion wave strong enough to blow the fuel out of the carb and prevent rpm above about 3200 rpm. Runs bad well below that. I use an open ended end cap. It allows straight ...
by pcnsd
Tue Jun 08, 2021 1:26 pm
Forum: Engine Tech
Topic: Any Way To Get This Exhaust Down To 95 Decibels Or Lower Without Destroying Good Flow?
Replies: 27
Views: 1610

Re: Any Way To Get This Exhaust Down To 95 Decibels Or Lower Without Destroying Good Flow?

David, As Rick expressed, I have packaging concerns regarding fitment. I am currently limited to a 4 inch muffler diameter due to swing arm clearance, but have considered a muffler based on a 4 inch radius oval. I choose to go with the adsorption tube model because I have experience with it and knew...
by pcnsd
Sat Jun 05, 2021 12:40 am
Forum: Engine Tech
Topic: Any Way To Get This Exhaust Down To 95 Decibels Or Lower Without Destroying Good Flow?
Replies: 27
Views: 1610

Re: Any Way To Get This Exhaust Down To 95 Decibels Or Lower Without Destroying Good Flow?

All the testing I've been subjected to was based on distance and rpm. I bought a decibel meter to confirm I could pass the testing. I can see that rpm and throttle position are related, but question with Rick the proposition that rpm is not a factor in sound generation level. On a practical observa...
by pcnsd
Thu Jun 03, 2021 9:27 am
Forum: Engine Tech
Topic: Any Way To Get This Exhaust Down To 95 Decibels Or Lower Without Destroying Good Flow?
Replies: 27
Views: 1610

Re: Any Way To Get This Exhaust Down To 95 Decibels Or Lower Without Destroying Good Flow?

It may be possible to meet your objectives with either a side resonant or diffusion resonator. Needed information: Current decibel level (plus frequency range, if known) exhaust pipe internal pipe diameter maximum total length of exhaust system. I simply found these pics online, I don't actually ha...
by pcnsd
Wed Jun 02, 2021 7:38 pm
Forum: Engine Tech
Topic: Any Way To Get This Exhaust Down To 95 Decibels Or Lower Without Destroying Good Flow?
Replies: 27
Views: 1610

Re: Any Way To Get This Exhaust Down To 95 Decibels Or Lower Without Destroying Good Flow?

All the testing I've been subjected to was based on distance and rpm. I bought a decibel meter to confirm I could pass the testing. I can see that rpm and throttle position are related, but question with Rick the proposition that rpm is not a factor in sound generation level. On a practical observat...
by pcnsd
Wed Jun 02, 2021 4:06 pm
Forum: Engine Tech
Topic: Any Way To Get This Exhaust Down To 95 Decibels Or Lower Without Destroying Good Flow?
Replies: 27
Views: 1610

Re: Any Way To Get This Exhaust Down To 95 Decibels Or Lower Without Destroying Good Flow?

1. What standard is tested to? 2. What RPM is the test is conducted at? I race that basic machine with some changes and must past sound at each race based on the J1287 off-hwy sound test at 96 db. I'll first say that observing the results of the testing over time makes me consider the test to be mos...
by pcnsd
Sun Apr 25, 2021 9:02 pm
Forum: Engine Tech
Topic: Air Cooled Hot Rod: Huge Oil Capacity Means No Need For an Oil Cooler?
Replies: 7
Views: 398

Re: Air Cooled Hot Rod: Huge Oil Capacity Means No Need For an Oil Cooler?

What is your application? Long or short time duration? Cruising or racing? It really depends on what your doing. I don't run an oil cooler on my single, have raced at 108F, but my races are over in under 4 minutes typically. Coolers add weight and are one more thing to damage if you crash. Races lon...
by pcnsd
Fri Apr 02, 2021 12:38 am
Forum: Engine Tech
Topic: Custom bent mandrel exhaust piece
Replies: 8
Views: 692

Re: Custom bent mandrel exhaust piece

There is little to nothing that can't be built from mandrel U and J bends. Knowing what you need and how to apply is the hard part.
by pcnsd
Tue Mar 16, 2021 11:23 pm
Forum: Engine Tech
Topic: This is for the Cylinder head Pros
Replies: 6
Views: 566

Re: This is for the Cylinder head Pros

I don't do it for a living, but driving out the old guides is relatively easy with an appropriate driver tool, a 3X rivet gun and a head heated to an appropriate temperature to facilitate the work. The ease of installing new guides depends on if there is a hard stop as part of the guide. If there is...
by pcnsd
Sun Mar 07, 2021 11:23 pm
Forum: Engine Tech
Topic: Air cooled cylinder head temp
Replies: 9
Views: 496

Re: Air cooled cylinder head temp

What’s a safe maximum temp on a force/fan air cooled small 125cc/232cc all aluminum engine? Currently seeing 311F as a maximum. The max oil temp is 261F. That’s more concerning and being hopefully handled by a small oil cooler and a switch from 0W-40 to 20W-50 Mobil 1. This thing holds 1qt. :shock:...
by pcnsd
Fri Feb 26, 2021 10:20 pm
Forum: Engine Tech
Topic: 3D printed inconel header
Replies: 19
Views: 1052

Re: 3D printed inconel header

I toured SpaceX in LA 5+ years back as a guest. This is the same process they used to build their directional thrust nozzles. I was impressed with the print technology at the time but questioned the time/cost factor. They said that the provided flexibility for their limited production needs was a go...