do you need premium gas with just a cam in the engine? or will it run a little more rough with out premium but still run good? i found a car but i'm not sure cause he puts premium in it and said it runs a little more rough (with the cam) when it has regular in it. i want to figure it all out today so i can call him back.
quick question about gas and need quick answer
- Thread starter 5.0kid
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97 king cobra
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its all in the timing, although im not sure how that would work for cars that have upgraded internal parts, i just have bolt ons
94Pro-5.0
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my motor as never seen nothing but premium
94kingcbra
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Premium definitely
I run 89, and sometimes even 87, but that's because I rarely floor it. My car pings like a sumbitch even with 91 octane (limp wristed fairy juice) which is the best we can get here. I only run 6* initial timing even.
When I go to the track, I mix in a few gallons of 100 octane unleaded to get rid of the dreaded ping. Meh. Phoenix gas sucks ass.
Paul.
When I go to the track, I mix in a few gallons of 100 octane unleaded to get rid of the dreaded ping. Meh. Phoenix gas sucks ass.
Paul.
AaRoN
King Post Whore
I run 89. Alot of the stations around here have really crappy gas, so just in case...
Schiffy
Well-Known Member
I only put in 87, with the occasional 93 when i feel like being nice (meaning when gas isn't $4/gal) I'm going to check my timing this week, my car is a turd, and i think that might have something to do with it...
had a buddy run his turbo'd fox on the dyno a few weeks ago, made a few runs on some wawa gas, drove down the street to shell and filled up,cam back and put her back on the dyno and picked up 25rwhp just off the gas from a different station :nonono:
had a buddy run his turbo'd fox on the dyno a few weeks ago, made a few runs on some wawa gas, drove down the street to shell and filled up,cam back and put her back on the dyno and picked up 25rwhp just off the gas from a different station :nonono:
thanks for all of the replies! i think i am going to go with my friend's aunt's BAB gt. it needs a little work on the exterior but it runs and drives great! it is all stock except flowmaster mufflers (welded on) and i should be picking it up next week cause of a radiator resevoir leak. i'm so excited!
Schiffy
Well-Known Member
5.0kid said:
wrong thread homie...
The cam timing does actually change the dynamic compression.
Static compression is what you calculate with your build spec's. My wife's 331 has 9.6:1 static compression.
Dynamic compression is what results from cylinder volume and valve timing events. When your valves open and close will have an effect on how much actual volume of air/fuel is captured in the cylinder and the resulting compression based on stroke and combustion chamber volume. To get nitty gritty, time actually factors in as well (RPM).
A cam with a shorter valve lift duration creates more dynamic compression. A cam with a longer valve lift duration creates a lower dynamic compression. That is why you run higher compression with long duration cams. This is a general statement because valve timing on the valves is what actually effects dynamic compression, but higher readings are typical with short duration cams and low readings with long duration cams.
This is how what cam you are running effects your octane requirement. On my wife's 331 with 9.6:1 compression and aluminum heads she runs 89 octane all the time. The timing is at 10 degrees BTD center. At 14* degrees it doesn't get any knocks or pings but it doesn't idle as nice as it does at 10*. It also idles faster at 14* than she likes. This is with 215* duration on the intake side but when the valves actually open and close in relation to each other (adjoining intake and exhaust events) comes into play. Anywaus this is what works on the street. Taking it to the strip I might bump it up to 14.
Steve
Static compression is what you calculate with your build spec's. My wife's 331 has 9.6:1 static compression.
Dynamic compression is what results from cylinder volume and valve timing events. When your valves open and close will have an effect on how much actual volume of air/fuel is captured in the cylinder and the resulting compression based on stroke and combustion chamber volume. To get nitty gritty, time actually factors in as well (RPM).
A cam with a shorter valve lift duration creates more dynamic compression. A cam with a longer valve lift duration creates a lower dynamic compression. That is why you run higher compression with long duration cams. This is a general statement because valve timing on the valves is what actually effects dynamic compression, but higher readings are typical with short duration cams and low readings with long duration cams.
This is how what cam you are running effects your octane requirement. On my wife's 331 with 9.6:1 compression and aluminum heads she runs 89 octane all the time. The timing is at 10 degrees BTD center. At 14* degrees it doesn't get any knocks or pings but it doesn't idle as nice as it does at 10*. It also idles faster at 14* than she likes. This is with 215* duration on the intake side but when the valves actually open and close in relation to each other (adjoining intake and exhaust events) comes into play. Anywaus this is what works on the street. Taking it to the strip I might bump it up to 14.
Steve
well, i'm trying to figure out what all im going to do with these heads i have. I think i may just wait a while and do a head/cam swap later this summer then an intake swap after that. does anyone know a good place to get a custom cam? I want to keep using 87 octane fuel and was wondering if a custom cam would be the way to go then. anyone have any suggestions? or should i just use the stock cam and do an intake and head swap?
all 3 suck major on our cars i think the worst part is the intake ....they had to make one last minute to fit under the hoods and they dont flow so well ...very restrictive....if i was you i would do a head cam since they are harder to do and you can pull the intake after those are on with no problems but i would talk around and get prices on porting your intake it will greatly help
