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calculator for hp with altitude, octane, c/r, and boost


Altitude factor?

What does it use for an altitude factor for a boosted motor?

Does a turbo or S/C lose about 1% per 1000 ft gain in altitude
or is it more like 0.5% per 1000 ft?
thanks
 
JIM BELL'S PERFORMANCE GUIDE

This data is intended as a guide only. It's the result of thousands of dyno runs and street testing with our company Ford, Mazda, Dodge, GM, Buick and Syclone/Typhoon vehicles.

1 psi boost = .5 point CR (EFFECTIVE COMPRESSION RATIO)
1 point CR = 2 psi boost (CYLINDER PRESSURE)
1 point CR = 2% HORSEPOWER
1 psi boost requires 1-1.5 octane (minimum)
1 psi boost = 6.8% HP max (1 ÷ 14.7 = 6.8%)
1 point CR = 3 - 5 octane
1 Air Fuel Ratio = 2 octane
1° advance = 1/2 - 3/4 octane point
10° engine coolant (160° -180° range) = 1 octane
20° ambient = 1 octane
1000' altitude = -1 octane point
1000' altitude = .5 psi (2" Hg)
6°F temp change = 1% air density
30% humidity = 1 octane
10° air charge temperature = 1% HP
20° charge temp reduction = .5 psi additional boost with same octane
3/4 PSI Drop = 5% pressure (5% x 14.7 = .75 psi)
ENGINE CFM = CID x RPM x VE*/2 x 1728
10% HP increase = 10% AF ratio with 100% VE
10 psi fuel pressure = 8% AF ratio: 5 psi = 4% AF ratio
HP = CFM (int @ 28") x .257 x no. cylinders
10HP = .1 sec / 1 mph 1/4 mile
100 lbs = .1 sec / 1 mph 1/4 mile
 
maybe I'm stupid but I don't know for sure

but by using this calculator is the line marked 16 the standard motor with no head shims or lc pistons?

it says 12 lbs boost with 93 octane is ok to run
and that 17.5 lbs boost with 99 octane is ok

is that right or am i crazy?
 

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As for base settings I use, for the -----------RX-1, 86 octane, 140 HP stock, 57 degree cam closing, head gasket thickness is .025-------------- Apex spec is, 86 octane, 150 HP stock, 71 degree cam closing, head gasket thickness is .017 Then you would plug in your new head gasket change, altitude and your boost setting giving you the octane requirements needed. If you decide to move the intake cam, that spec is also in there. I have seen some confusion on head gasket thickness. Some have measured the gasket including the embossed sealing hump. When the head is torqued these squish flat. The thickness I give you above are true installed specs. using stock replacement gaskets. Mike Knapp#17------------I pasted this here from another post as when I downloaded the calc it did not have what I consider an accurate baseline as far as base octane, cam closing, base HP and gasket thickness. Of course these are different for the RX-1 and the apex. I think this confuses some. This is a great calc. that takes the guesswork of of octane requirements.
 
The baseline has been updated for an Apex with stock cam timing at 71 deg abdc and an .076 head gasket. When The Vector baseline compression has been updated to 11.3. Hope this helps.
 
So the way I read it - with my RX1 - If I put in a .076 head gasket - I can run 15 lbs of boost on 92.9 octane (+/- a few octane). I would lose roughly 5 HP on the stock motor and get roughly 272 HP on full boost (again with some margin of error). Am I reading it right?

Is the .076 headgasket a Yamaha part or aftermarket and if so, then where to find it?

Thanks in advance.
 
Is there enough info floating around to put a line on the calculator for the new Nytro?
 
OK....not sure if I am using this calculator right. 06 apex with a stage one SC 10lbs boost 10k feet elevation no head shim/stock timing and I get 92.8 octane...is that correct or did I do something wrong. I have been told numerous times that I could run 91 octane riding our elevation.
 
Running stock compression and ignition timing you will need 93.8 to be safe. Running it on 91 is walking on mines and a disaster waiting to happen.
It may live or it may not, I wouldn't bet on it tho.
I recommend adding a headshim to lower compression, you will run safer and you will be able to run higher boost.
 
TurboKeith said:
Try out this boost, octane, and horsepower calculator that I threw together.
Let me know if it looks pretty consistent with what you've found.

Updated 10-15-07 with the Nytro info and a cam timing lobe center calculator.

boost calc
Click to expand...
just how do you use this i have an 08 stock nytro with 180 kit please & thanks
 
Is the "base octane" number the number your putting in at the pump? If so, what changes the number form what you put in "base octane" column to a different number in the "octane" column if you have 0 for elevation and boost? Just trying to understand how it is calculated and why it would change with no boost added?
 
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