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by David Redszus
Thu Jan 16, 2020 10:32 am
Forum: Engine Tech
Topic: 100 Octane Pump Gas by 2020?
Replies: 137
Views: 11539

Re: 100 Octane Pump Gas by 2020?

The IDEAL combustion of any hydrocarbon is:

HC + O2 --> CO2 + H2O

The actual combustion of any hydrocarbon is:

HC + O2 --> CO2 + H2O + hundreds of trace amounts of obscure hydrocarbons.

In fact, what comes out of a tailpipe often does not resemble what goes into the engine.
by David Redszus
Thu Jan 16, 2020 10:23 am
Forum: Engine Tech
Topic: What is cylinder head choke
Replies: 18
Views: 1004

Re: What is cylinder head choke

So it sounds like “choke” would be the same thing as (term wise) running out of port, valve, curtain, etc. On a flow bench, would this “choke” point be were flow stops increasing even with more and more lift, at a constant depression? Flow separation, or “going turbulent”, is easily seen/heard on a...
by David Redszus
Thu Jan 16, 2020 10:19 am
Forum: Engine Tech
Topic: Plastagage versus bore gauge
Replies: 42
Views: 1654

Re: Plastagage versus bore gauge

Running with the hijack ball: that would be really interesting! I suspect all the PG strips would end up as near-transparent blots a half inch wide. Of course for an accurate picture the use of pressure indicating film would be preferable: https://www.sensorprod.com/glossary/pressure-indicating-fil...
by David Redszus
Wed Jan 15, 2020 7:13 pm
Forum: Engine Tech
Topic: Plastagage versus bore gauge
Replies: 42
Views: 1654

Re: Plastagage versus bore gauge

A recent head sealing project and the mention of Plastigage brought an idea to mind. Suppose we were to take a nice clean block surface, lay down several strips of Plastigage, install a nice clean head and torque to specs. What range of clearances are we to expect? Does the head/block surface remain...
by David Redszus
Wed Jan 15, 2020 7:03 pm
Forum: Engine Tech
Topic: What is cylinder head choke
Replies: 18
Views: 1004

Re: What is cylinder head choke

Choke is an engineering term to signify sonic flow has been achieved, and at that point any increase in pressure ratio cannot increase velocity. This is not what happens in an intake port. I believe it is used commonly and incorrectly when a different aerodynamic phenomena occurs - flow separation....
by David Redszus
Wed Jan 15, 2020 11:13 am
Forum: Engine Tech
Topic: What is cylinder head choke
Replies: 18
Views: 1004

Re: What is cylinder head choke

Choked air flow is always a function of pressure ratio.
by David Redszus
Fri Dec 20, 2019 11:44 am
Forum: Engine Tech
Topic: What's my best chance getting rings to seat/seal on this?
Replies: 32
Views: 2899

Re: What's my best chance getting rings to seat/seal on this?

If this were my project, given the financial constraints, I would use your rigid stone to minimize the top ridge, taking off as little as possible. Then I would use a coarse ball hone followed by a few strokes with a finer ball hone. As mentioned earlier, cleanliness is essential. Use a conforming c...
by David Redszus
Fri Dec 20, 2019 11:35 am
Forum: Engine Tech
Topic: Rod bolt stretch
Replies: 19
Views: 911

Re: Rod bolt stretch

Tightening torque (with a torque wrench) only refers to the frictional force of threads, bolt head, and washer. It does not measure anything else. Depending on thread cutting method (cut, rolled or ground), the friction factor can range significantly (0.08 to 0.22). Tightening the bolt in several st...
by David Redszus
Tue Dec 17, 2019 7:49 pm
Forum: Engine Tech
Topic: Valve springs
Replies: 18
Views: 919

Re: Valve springs

I disassemble my engines to the last nut and bolt, dip everything in Cosmoline and seal the parts in argon-filled bags. The Earth thanks you for not using a greenhouse gas, Sir. Cosmoline is a wax based oily hydrocarbon which must be protected from exposure to air in order to avoid solidification. ...
by David Redszus
Tue Dec 17, 2019 12:48 pm
Forum: Engine Tech
Topic: Valve springs
Replies: 18
Views: 919

Re: Valve springs

Springs stressed past yield are not going to last many cycles Good point. We can compress a spring to coil bind and it will return to its original free length provided we stay in its elastic range and not venture into its plastic domain. Proper spring design is required to accomplish this. Ferrous ...
by David Redszus
Tue Dec 17, 2019 12:33 pm
Forum: Engine Tech
Topic: spark plug gap vs lean mixtures
Replies: 74
Views: 3097

Re: spark plug gap vs lean mixtures

On the other hand, lean mixtures burn slower and need more advance for optimum fuel economy. That is true, however, we're not looking to run at "lean" mixtures, so much as we're looking at "not rich". We're also not looking to run for best economy, we're trying to make it light off cleanly at stoic...
by David Redszus
Tue Dec 17, 2019 12:13 pm
Forum: Engine Tech
Topic: Engine oil temps
Replies: 55
Views: 1917

Re: Engine oil temps

The topic of oil temperature cannot be separated from other operating parameters that affect wear and reduced friction. Starting with viscosity (cSt) vs temperature for various oils: Temp F...10w-30.....5w-50......20w-50 cSt 200...........13.5........21.9.........23.5 250............8.0........13.2....
by David Redszus
Sun Dec 15, 2019 6:42 pm
Forum: Engine Tech
Topic: Valve springs
Replies: 18
Views: 919

Re: Valve springs

The metal used to make a valve spring has a specific tensile strength which is expressed in units of pounds per square inch. Since the tensile values are often quite high (150,000-175,000psi), the unit Ksi (150Ksi) is often used. When a spring is compressed, a stress is imposed upon the spring, whic...
by David Redszus
Sun Dec 15, 2019 6:12 pm
Forum: Engine Tech
Topic: spark plug gap vs lean mixtures
Replies: 74
Views: 3097

Re: spark plug gap vs lean mixtures

Many years ago I experienced the flip side of large plug gaps. During a hasty midnight valve job on a Morris Mini Minor we left the spark plugs in. When we fired it back up it would only run on three cylinders at idle and low load, but #4 would chime in above maybe 25% throttle. Pulled the plugs an...
by David Redszus
Wed Dec 11, 2019 9:30 pm
Forum: Engine Tech
Topic: Laminar Flow
Replies: 8
Views: 413

Re: Laminar Flow

In actual engines, we rarely if ever, see laminar flow.

Almost all air flow is turbulent flow.