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Questions tagged [engine-theory]

Use this tag when asking questions about the theory of engines. Do NOT use for practical problems, only theoretical questions

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Is there any advantages of the mounting side (left or right) of the motor in a FWD vehicle?

Almost every FWD I have dealt with has the engine on the left side and the transmission on the right. Hondas with the D17 Engine has it the opposite which made me curious. Does the mounting side of ...
method's user avatar
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3 votes
1 answer
978 views

Does an oxygen sensor's lambda value represent the same when running on LPG?

I have converted my car to LPG, and i've been tuning it today with a wideband lambda controller. It runs pretty okay, but i'm not yet satisfied. The weird thing is, it accelerated best when the ...
Bart's user avatar
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3 votes
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Would a camless engine need a starter motor?

In theory, if you had a working camless engine with fully variable valves... Would it be possible to just have the engine start itself by choosing the most appropriately placed cylinder at the time ...
Guest's user avatar
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2 votes
3 answers
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Atkinson Cycle: Does the efficiency of a high-compression engine come from compression ratio, expansion ratio, or both?

I understand that, in an internal combustion engine, efficiency can often (up to a point) be improved by increasing the compression ratio, this being a major reason why diesel engines (which do not ...
DodoDude700's user avatar
2 votes
0 answers
49 views

How to analyse engine oil analysis results?

I got an engine oil analysis done on my 1991 CAT 3116 with 124,000k miles on it. I received a sheet of what I presume to be the result of some kind of spectrometry. As I'm not an analytical chemist, I ...
Joe B's user avatar
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What would happen if you tried to start an engine with the cam gears meshed

What would happen in the case that someone tried to start an engine like this: My guess would be, if the starter has enough torque to overcome the strength of the cam gear teeth, it'd wreck the cam ...
Ceshion's user avatar
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1 vote
0 answers
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Given compression ratio for a naturally aspirated engine, how do I calculate the expected compression pressure?

I've started learning more about cars, and I have a question. How do I know what compression pressure I should expect during a compression test? With a naturally aspirated engine, I think I can use ...
Wren T.'s user avatar
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1 vote
2 answers
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Differences between drive by wire and drive by cable

What are the main differences, advantages, and disadvantages of using a drive-by-wire versus drive-by-cable system?
Anilla's user avatar
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1 vote
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Optimizing temperature and spark for horsepower

I recently completed a heads+cam project on my car to increase horsepower. I ended up falling about 50hp short of my goal, and am looking for every little knob I can turn to eek out that last little ...
user2864293's user avatar
1 vote
0 answers
69 views

Pencil Coil Operation

Pencil coils are very small. Do they operate on the CDI Principle? I thought that CDI was not good on lean mixtures which are good for fuel economy? Do they operate on the accepted Inductive Discharge ...
Autistic's user avatar
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Crankshaft design

I am wondering why all crankshafts I see are machined so that the piston rod counterweights are all tapered at the rod bearing end of the counterweight? As you can see in the picture the ends of the ...
nuk's user avatar
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2 answers
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Does engine braking still save fuel at right above idle?

I'm trying to drive economically and my understanding is that as long as there is enough momentum in the car to keep the engine spinning while in gear at above idle the engine won't inject more fuel, ...
Aden's user avatar
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1 answer
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Reverse flow head vs Cross flow head

Wikipedia says that Cross Flow cylinder heads induct the charge better because the gases doesn't have to change direction from intake to exhaust. Thus the higher inertia of flow of gas in one ...
Abhishek P G's user avatar
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0 answers
86 views

Overhead valve Vs Overhead cam

Sure overhead cam is better at high revs because valve accuracy is superior.At normal average revs like say 3000rpm the advantage is not really there but the extra cams will chew more mechanical power ...
Autistic's user avatar
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0 votes
1 answer
302 views

Camshaft valve clearance and fuel consumption

Does the clearance between the camshaft and the top of valve tappets (AKA lifters AKA shims) affect fuel consumption? I am asking because it seems to me like the lesser the spacing, the more the cam ...
amphibient's user avatar
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Why do Tri-Y Headers give more low end torque and struggle at top and why 4-1 Headers give better top end torque?

Everywhere i read says Tri-Y is better for bottom end and that the 4-1 is better for top end. Why exactly is that? I thought Tri-Y would have more top end "breathing" and make more torque at ...
Timothy Scherer's user avatar
0 votes
1 answer
150 views

Is it true that crankshaft counterweights help with extending the life of the main bearings?

I have heard that use of counterweights in crankshafts also help with bearing life because "counterweights reduce peak main bearing inertia loads". Is this true? If its true how does that ...
Timothy Scherer's user avatar
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0 answers
125 views

How does engine braking mapping work?

Some recent cars and a lot of bikes can change engine mapping and change engine braking electronically. For instance, my bike is not an automatic bike, so it has mechanical gears and I am able to ...
LP154's user avatar
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0 answers
390 views

How to design an exhaust pipe to increase scavenging at specific RPMs

Good day all. I'm looking for advice on an exhaust design problem. It is easy to find videos explaining exhaust scavenging, but how do you control it? Surely there must be some physics that can be ...
Laine's user avatar
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0 answers
219 views

Cleaning ground rotor magnets dust and particles after rotor assembly damage

I happen to have an FZ8 motorcycle which is famous in warmer climates like Greece for a very serious failure (along with FZ1 and R1) in the rotor assembly. In many cases the glue holding the magnets ...
kokobill's user avatar
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1 answer
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Car struggles to pull off up hill

Could anyone help with another issue/potential issue I have? When I am parked on a hill, facing upwards, I put my car into first gear and when I pull off it feels as if I am towing something heavy, ...
Scott's user avatar
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Does an engine with lower viscosity oil require less warming up?

I have always seen that an engine should be driven gently (low throttle, low revs) for about 15 minutes after starting, in order to bring the oil up to temperature and lubricate the engine properly. ...
James Monger's user avatar
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0 answers
56 views

Which vehicle came with the most different engine cylinder configurations?

A question that cropped up in a discussion today... Most vehicles sold come with one or two different engine cyinder configurations, for example and inline-4 and a V8. Quite a few have three, and a ...
Nick C's user avatar
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-1 votes
1 answer
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3 wheeled light commercial vehicle sound

I'm new to this platform. So I'm not sure if my inquiry is appropriate to publish here. If not, kindly direct me to the appropriate forum. I've noticed that three-wheeled commercial vehicles produce ...
Robin's user avatar
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-1 votes
2 answers
346 views

2014 Jeep SRT 6.4L oil filter was too small - what kind of damage?

What possible damage could my engine incur from having an oil filter installed that is smaller than the suggested size? I have damage but I’m interested to hear what this forum has to say about it ...
Josh Galloway's user avatar
-1 votes
1 answer
99 views

What control the RPM of an engine?

can you tell me what controls the rpm of an engine? Is it more fuel, more rpm (if so plz explain this to me) or is it controlled by a computer?
Tintin's user avatar
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-2 votes
2 answers
870 views

Could a wind turbine work for a car?

Could I attach a little fan to power a motorcycle alternator to be more efficient then running off the engine? Attach any where facing the wind on the vehicle to increase mileage from eliminating ...
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