Quote:
Originally Posted by NewCar
The irony of all this is that the V6 which runs on regular 87 actually has a higher compression ratio than that of the v8 which runs on premium. If compression is the main issue, then I wonder why this is?
11.3:1 (v6)
10.7:1 (LS3)
10.4:1 (L99)
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its not irony. its two different motor designs. the v-6 is Direct Injection, meaning the fuel is sprayed directly into the combustion chamber (much like that of a diesel) momentarily before the ignition sparks. this allows a higher c/r as the fuel also cools the air charge when it is sprayed into the cyl as well as allows for more accurate fueling as you dont have some fuel sitting in the intake runner/on the valve not making it into the combustion chamber.
Quote:
Originally Posted by NewCar
  so if it is so high pressure then why does it not need the higher octane to avoid knocking? |
cus its DI. I would still run premium in it. but thats just me.
Quote:
Originally Posted by NewCar
CamaroSpike23
a rough guide for Compression ratio vs Octane
5:1 67
6:1 75
7:1 82
8:1 87
9:1 91
10:1 93
11:1 95
12:1 103
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and to add a note to this guide. it is for traditional n/a motors. I have not done much work with tuning DI motors (save for diesels)
Quote:
Originally Posted by 69Firebird
The LS3 is sweet, but if they added DI it would be out of control. More power and better fuel economy.
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thats what the Gen V motors are for.
Quote:
Originally Posted by UsedTaHaveA68
Agreed. I don't understand why engines haven't been DI'd for years now. Diesels have always been direct injected (or at least for as long as I remember). I remember when Mercury Marine came out with DI in their outboard motors back in the mid '90s, but autos still aren't getting them. Why WOULDN'T they use something to increase the efficiency of an engine?
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diesels have been DI'd since their conception. but its all about the workings of the different motors. Diesels work by way of the..... wait for it...... diesel cycle. while some have glow plugs, most often, they do not. and they operate by way of detonation. ya know.... the thing we are all worried about here. reason being is that diesel motors are built to run with a lot higher compression as well as the combustion cycle being triggered off of compression and heat instead of a spark plug like that of the Otto cycle.
they have been looking at DI gasoline for years now. but the thing to keep in mind is that, its never really been needed. as automotive consumers, we've told motor companies we want more power, we want more room, we want better mileage, and they have been more than happy to squeeze every little bit they can from the tried and true design of the small block v-8. not to mention that DI fuel injectors arent cheap....lol and one thing everyone needs to keep in mind is that V-8s of the traditional sense are going to be changing. Gen V motors will be making an appearance in vehicles soon. but motors will be going in a different direction in the future.
Quote:
Originally Posted by tylermoore
nitrous plus race gas!!!
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Quote:
Originally Posted by zebra
that would be GREAT for a daily driver!
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yeah... if you had the race gas as a stand alone fuel setup in addition to regular fuel. it would be about a waste to run on it full time.