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[Joes924Racer]

In a book called "Souping the Stock Engine", it included a section on estimating peak horsepower when souping a stock block. using a method using a factor for each type of modification. The following are multiplier factors for each souping step.
Special aluminum head........from 1.08 for 7.5:1 CR..... to 1.16 for 12.0:1 CR
Adding carbs and intake manifold........ 1.10 for 1 barrel per 3 or 4 cyl. 1.15 for 1 barrel per 1 or 2 cyl.
Reground cam........ from 1.08 for a semi grind..... to 1.22 for a super race grind Porting and relieving..... 1.05 to 1.08 (varies depending on severity)
headers full flow exhaust .....1.00 to 1.05
Boring and stroking...... 1.00 plus 0.7 times the percentage increase in displacement (use 1.0 if larger valve are used)
Methanol..... 1.10 (scale down with lower alcohol content)

How about an example? Suppose we started with a 110 hp na motor. that was 1984 cubes from the factory. Say we radically ported and polished the heads., single throat throttle body with 3/4 inch spacer, intermediate racing cam, stock bore and stroke, and will run it on gas.

Starting from the top and going in sequence.....
single throat throttle body with spacer factor shoud be 1.00
Porting should have a factor of about 1.06.
header full flow exhaust factor of 1.05
A reground intermediate cam factor should be about 1.08.
There is no multipliying factor for running on gas.

Now we multiply these factors together or (1.00)(1.06)(1.05)(1.08 )=1.20 to get our total factor. The estimated peak hp of our modified engine is the original hp rating times the total factor or (110hp)(1.20)=132 hp.

Whew... some work out huh? Anyway we have something new to play with now on cold winter nights.

Joes924racer
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1979 porsche 924 Na
1980 porsche Turbo 931GT Replica
Have u ever driven a turbo.