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Dan the man

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This is something that everyone wants to improve on. I've read articles on here guy's asking how much compression can they run. It seems to me that building a engine going by pure stock drag racing rules a guy could build a strong running engine without a 10.0:1 compression ratio. Those guys have gotten some impressive results from a lower cr.
 
I don't even get the point of that post..
 
Not sure i follow - is this a question?
Many factors contribute to how much compression you can run without detonation issues - Fuel, altitude, camshaft, operating temps, combustion chamber design, alloy/cast iron heads, tune ect.
Dynamic compression is what you need to be looking at
 
I don’t see why the average street guy wants to push CR level. 1 point is worth
about 4% hp so 300-500 hp is what a lot people are running equals 12-20hp.

To me pick your cam and gas you want to run and go with a CR that will work with a safety margin with that.

Some guys with experience running high Cr and pushing things to the limit that’s good for them but most will end up with pinging mess of an engine that they can’t figure out.

Most of us are not in highly competitive race classes where every last hp counts.
 
Correct me if i'm wrong but I don't believe there is a compression limit nor a displacement limit either in the Pure Stock and also the F.A.S.T class series of racing and so yes any of them that want to compete at the top will push all they can.
 
Dan the man said:
This is something that everyone wants to improve on. I've read articles on here guy's asking how much compression can they run. It seems to me that building a engine going by pure stock drag racing rules a guy could build a strong running engine without a 10.0:1 compression ratio. Those guys have gotten some impressive results from a lower cr.
Click to expand...
UUuuuuuuuhhh, Okay!

ok.jpg
 
9.5:1 is a comfortable place. Build from there. 10.5:1 with aluminum heads.
 
Bakerlite said:
Diminishing returns as you go higher in comp..
There is no "average"..
Click to expand...
There's no real gain unless you go to like 12.5:1 or higher. I like pure stock drag engine building rules as it makes you get the most out what you have to work with from the factory.
 
Bakerlite said:
Diminishing returns as you go higher in comp..
There is no "average"..
Click to expand...


Yes I know but don’t want to write a book every time I answer someone, 4% is usually considered the rules of thumb.
 
Dan the man said:
There's no real gain unless you go to like 12.5:1 or higher. I like pure stock drag engine building rules as it makes you get the most out what you have to work with from the factory.
Click to expand...

going from 7:1 to 8:1 gives more hp gain then 14:1 to 15:1 but people usually go by the 4% average
 
Dan the man said:
There's no real gain unless you go to like 12.5:1 or higher. I like pure stock drag engine building rules as it makes you get the most out what you have to work with from the factory.
Click to expand...
Maybe you should go back and read the rules as I think you confused and or have reading comprehension issues or maybe only believe what you want......either way you are wrong.
 
Poop in one hand and crap in the other. Mopar Motor building expertise from a non Mopar owner….

Do ya want a hot rod, or do you want a stocker? Your choose, but I want to highest CR I can for the application of the motor…. The 340 stroker I’ve been collecting stuff for, I want in the 13 range, so I can mix some AV gas and pump gas and call it a day…
 
273 said:
Yes I know but don’t want to write a book every time I answer someone, 4% is usually considered the rules of thumb.
Click to expand...
Well it's a misleading statement, explain the whole theory or just don't say anything..
Now some idiot is going to read what you posted and think it applies to every comp change...
Just post this in the future:

CompChange.jpeg
 
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'68cuda416 said:
Correct me if i'm wrong but I don't believe there is a compression limit nor a displacement limit either in the Pure Stock and also the F.A.S.T class series of racing and so yes any of them that want to compete at the top will push all they can.
Click to expand...

In Pure Stock, like what is run at the PSMCDR event every year, the rules are pretty restrictive.
The compression rule was revised several years ago to allow:
Factory advertised CR, +1.5 points.
Rules

No strokers, no big cams, no porting on anything.
Can’t even run a line lock.

The F/S class in FAST is supposed to be the same.

The actual “F.A.S.T.” Class has very open rules, with the emphasis on the car “looking” stock........ the “A” is for “appearing”.
So, strokers, ported everything, high CR, roller cams, etc are the norm there.
 
Dan the man said:
This is something that everyone wants to improve on. I've read articles on here guy's asking how much compression can they run. It seems to me that building a engine going by pure stock drag racing rules a guy could build a strong running engine without a 10.0:1 compression ratio. Those guys have gotten some impressive results from a lower cr.
Click to expand...

I'll take a stab at it:

You have to have a full understanding of ALL of the rules associated with classes like Pure Stock, Stock Appearing, NHRA Stock, Factory Appearing Stock Tire & others and not get them mixed up. I don't know all of the rules, but there are usually allowances that are not "pure" or actually "stock" anyway. Despite the best efforts of the rule makers, there are creative "grey areas" and rule "interpretations". Some people do achieve surprising performances. Detailed blueprinting helps a lot because "pure", OEM engines are usually pretty far off from printed specs. But the more rules/restrictions there are, the more expensive it is to achieve maximum performance out of a combo, which includes a lot of assorted fine tuning throughout the car. Not the best, simplest, cheapest or easiest way to reach an ET/MPH goal. But some people like and can afford the challenge.
 
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