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Engineering/Technical Ask technical questions about cars. Do you know how a car engine works? |
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05-23-2002, 01:12 PM | #31 | ||
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05-23-2002, 03:25 PM | #32 | |
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All else being the same, having an extra spark plug in there would increase the compression ratio slightly, would help cool down the engine (an additional heatsink), leads to more efficient burning, so what's to lose?
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05-25-2002, 07:29 PM | #33 | ||
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A sparkplug is rather a hotspot than heatsink. Twin sparkplugs is used when a cleaner and more efficient combustion is wanted at low and mid rpms, and if there is hard for one plug to ignite the fuel and/or if the fuel is burning slow like in Top Fuel dragsters. |
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05-26-2002, 12:03 AM | #34 | |
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Sorry, I forgot.
Why are there heat ratings for spark plugs then?
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05-26-2002, 01:29 PM | #35 | |
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They're for controlling tip temperature, to prevent them from becoming so cold that they foul and so hot that they cause ignition pre-ignition.
There's nothing wrong with two spark plugs per cylinder, it's just that they don't really fit properly if you have more than three valves per cylinder. Mercedes found it beneficial for efficiency and emmisions to remove one valve in order to add a spark plug, which isn't surprising given that it does help low to midrange engine operation (where their engines spend about 90% of their life). SaabJohaan- For combustion to travel fastest and exert maximum pressure on the piston crown during high RPM operation, a large bore and small stroke are what you're looking for (not the other way around). Additionally, such a setup has a smaller surface area to volume ratio, which if you're that worried about efficiency would be the way to go. Remember its not just about surface area, its about volume vs. surface area. On a displacement vs. surface area basis, old pushrod 2 valve V8's have a significantly better ratio than most any modern four cylinder motor.
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05-26-2002, 02:37 PM | #36 | |
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On a another note: Why is the Viper's V10 still using pushrods?
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05-26-2002, 04:05 PM | #37 | ||
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05-27-2002, 06:29 AM | #38 | |
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It's already big enough...
I've got a question though - why does it only make ~60HP/L?
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05-27-2002, 11:29 AM | #39 | ||
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Large bore with small stroke have a larger surface area/volume than small bore and large stroke, but is anyway better in a high rpm operation like you said. A four cylinder engine will always have better surface to volume ratio than an eight cylinder engine if they have the same volume and have the same type of head. I didn't mentioned the volume since my comparison was between few and large cylinders against small and many cylinders. |
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06-08-2002, 01:08 PM | #40 | |
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these are generalizations.
larger displacement makes more torque air flow makes more power it's easer to get air in to a small cylinder than a larger one at higher engine speeds. also larger bore size can make it easer to get air into an engine. for a given dispalcement. a V12 6 L is just 12 smaller one cylinder engines added together. a V8 6 L is just 8 larger one cylinder engines added together. torque is about the same. the v 12 will almost aways be able to breath better at higher R.P.M. and make more HP. every thing else being the same. .........ft/lb of torque * R.P.M. HP= -------------------------- ....................5252............... how does one get sucked in to answring a question. that has no real answer? |
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06-08-2002, 05:52 PM | #41 | ||
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06-08-2002, 06:22 PM | #42 | |
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i THINK
I think I got my threads crossed.
I was repling to something else. |
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06-21-2002, 10:58 AM | #43 | ||
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When the Viper's engine was designed, it was derived from an existing OHV V8. In order to develop the V10 as a SOHC unit, it would have been much more expensive and taken longer. The Viper went from concept to assembly line in 3 years. Very good for a vehicle that was on a unique platform using a unique (albeit based on an upcoming volume engine's design) engine. I forget the exact numbers, but the cost of the Viper project was relatively low. |
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06-21-2002, 05:26 PM | #44 | |
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yeah I know what ya meen.
the v 10 iis big enough already.
I have been thinking about this so what if your engine is smaller on the inside it matters how big it is on the outside. that and weight. and fuel consumption are the only real things worth thinking about |
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06-22-2002, 02:10 PM | #45 | |
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fuel consumption schmuel consumtion! When i get me a deuce and a hlaf, ill be mkaing a good 8 miles a gallon! If that! or mabbe an M1 abrahms, 2 gallons a mile...hmm
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