compression difference

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0ld school

0ld school

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va.beach, va
i just had my short block rebuilt. it specs:
500"
295 sr,s flowed 365 cfm
solid roller 272/276 @.050 650"
mopar 337/ 1000 cfm 4150

the cr comes out at 11.8. to high for pump gas, but not high enough to really justify race gas.

my question is, how much power am i leaving on the table not going with 13-1 cr? i'm thinking about cutting the deck, to raise the cr to about 13-13.5. what do you guys think?
1343795-scratchchin.gif
thanks
 
I'd never again run a BB on the street over 10.5 compr. Pump gas premium, especially now that they're mixing in ethanol, is crap for high compression and you end up retarding the timing just to keep it out of detonation. You end up leaving a lot of HP on the table you can't use. Done that been there.
 
As said above 10.5 on the street maybe 10.8 with aluminum heads anything more and you will have to run fuel. You are right that you are in no mans land where you are but 13.1 is race only and the motor will need lots of attention, where you are at now you can mix some 100 octain sunoco with your 93 50/50 and you should be ok. Still going to be expensive to operate.

I would give up the power and lower the compression to make it a pump gas motor you will be much happier in the end.
 
i decided to break it down and cut the decks, to raise the cr to 13.1-1. i could not see leaving all that easy power on the table. the machine shop is going to cover all of it. good thing i checked it. i would be wondering where the power was....
 
Just go ahead and order a 55gal barrell of 113vp, its only money right. Is this a saturday night special grudge car.
 
What is your dynamic ratio? static doesn't really mean **** if you bleed off most of the cylinder pressure with a big cam.
 
Plik said:
What is your dynamic ratio? static doesn't really mean **** if you bleed off most of the cylinder pressure with a big cam.
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Correct, i'm running 11.25cr with j heads, 93 works fine with 30 total, seemed to run the same with 110 leaded at 35 total. i have 205 cranking psi, if i'm going to race it then i'll add race gas and bump the timing. also a lot of other things go into your octane requirements like quench, stall converter, car weight, fresh air system, fuel temp, etc..
 
skypower said:
Just go ahead and order a 55gal barrell of 113vp, its only money right. Is this a saturday night special grudge car.
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it's only gas money :yawinkle:. i do buy it by the drum, many drums. all my other cars run race gas, so this one might as well too..
 
I don't know what premium fuel you guys have but all the stations here in WI have NO ethanol in the premium, it is 93 octane, this is from Kwiktrip, now alot of the guys around here that don't want to pay for race gas have switched over to E85, E85 has 110octane and theres a guy at our weekly car show that is running it in his TA 455, and he is running 13.5 to 1 he loves it you will burn approx 30% more but it is waay cheaper than race gas. just a thought if you want to run 13.5 to 1.
 
Not technically legal due to road tax issues, but 100LL Avgas might have been a solution. Most airport FBO's won't let you drive a car to the pump, but you can always fill cans or a 14 gallon pump-n-go.
 
0ld school said:
it's only gas money :yawinkle:. i do buy it by the drum, many drums. all my other cars run race gas, so this one might as well too..
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Well your allready setup so just go out and have fun, most of the guys around here can't burn $100 in fuel to play for the evening, but looking at your stable of rides I don't think it will change your life style much so I say what the hell, not any different than me flying half way across the state to get hamburger these days. It's all about having fun.:toothy7:
 
skypower said:
Well your allready setup so just go out and have fun, most of the guys around here can't burn $100 in fuel to play for the evening, but looking at your stable of rides I don't think it will change your life style much so I say what the hell, not any different than me flying half way across the state to get hamburger these days. It's all about having fun.:toothy7:
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skypower, are you a pilot also? i am, i own and fly a bonanza. i have had many $ 100.00 hamburgers.....
 
Yep, but I am plane less at the moment been thinking about getting something like a Lance to go back and forth to North Carolina and South Carolina form Tampa. Wifes family is in Myrtle Beach and my Dad is in Murphy N.C. area so we are all over the place and i'm getting fed up with the drives. Only problem is i'm not IFR so kinda of a pain with the weather plus the wife works for someone else so has to be back a certin time unlike me. Bonanza's are very cool fun to fly.
 
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