4.1 trash!!!

[Ttype6]

If we increase the size of the valves,open and close them faster and farther,increase the diameter of the cylinders,and increase the stroke, air moves through the motor with less effort. If we do all of these things and nothing else,the boost will be lower but the motor will still be getting the same amount of air or more and will make the same amount of power or more. If I wanted to see 30 lbs of boost with my 273 291,I'd have to use a much larger turbo. It would probably have to be large enough to move an amount of air that would support 900 -1,000 hp. You can expect either block to break at these power levels.

Boost pressure is a measurement of the air that is not entering the combustion chambers. It is easier to get more air into a bigger motor with less effort,so comparing a larger and smaller motor's boost numbers is an apples to oranges comparison. The smaller motor has to run more boost to make the same power as the larger motor. To say that the larger motor is less reliable at higher boost is not a bad thing because it doesn't have to run as much to make the same power as the smaller motor and everything that happens with the bigger motor will happen faster while producing more of the most important thing (torque).

 

[Ed Valvo]

109 blocks in the 9's and non stage 2 head cars in the 8's was a dream way back when I got into these cars. Now it is being done more regularly than ever before. Had a few local racers try the 4.1 and all went back to the 109 or went Stage 2 due to failures but that was before the internet forums where info could be shared. I'm sure proper block selection is key as with any build. I can only assume the trick to making these 4.1's last has been found. Hopefully it won't be a secret.

 

[robzombie]

If we increase the size of the valves,open and close them faster and farther,increase the diameter of the cylinders,and increase the stroke, air moves through the motor with less effort. If we do all of these things and nothing else,the boost will be lower but the motor will still be getting the same amount of air or more and will make the same amount of power or more. If I wanted to see 30 lbs of boost with my 273 291,I'd have to use a much larger turbo. It would probably have to be large enough to move an amount of air that would support 900 -1,000 hp. You can expect either block to break at these power levels.

Boost pressure is a measurement of the air that is not entering the combustion chambers. It is easier to get more air into a bigger motor with less effort,so comparing a larger and smaller motor's boost numbers is an apples to oranges comparison. The smaller motor has to run more boost to make the same power as the larger motor. To say that the larger motor is less reliable at higher boost is not a bad thing because it doesn't have to run as much to make the same power as the smaller motor and everything that happens with the bigger motor will happen faster while producing more of the most important thing (torque).

Yes I agree with what most have been saying, but you can do all that with a 109 stroked to a 4.1 and you have the same thing, only you know it will not break as they have been taken to higher stress levels and live.

I never disagreed with why a 4.1 is better than a 109 except that a 109 WILL live versus a 4.1 that may or may not live.

I eagerly await proof of the magic 4.1 that will live into the low 9's and high 8's.

 

[gnmaster2004]

How about the 3.8 hot air block. Can that block take some abuse? Has anyone made some good power without a girdle?

 

[20psiofevil]

Anyone ever cryo freeze a block?

My motor is 260 cubes and will say for sure displacement makes a huge difference but top end (heads and cam) is where it's at, that and rpm.