More cubic inches affect VEs? focusing on IVC
03-08-2013, 08:38 AM
#1
TECH Enthusiast
Thread Starter
More cubic inches affect VEs? focusing on IVC Consider I am using a 42 IVC on my 346 LS1.
If I elect to go 408 (3.75"stroke) how do the additional cubes and change in stroke affect the value I select as my IVC?
I would like to retain the same peak HP rpm and cam accordingly.
I notice the 364/6.0liter blocks which are only a wider bore peak at a lower rpm than a 346/5.7 for the same camshaft values. Now, I am changing the stroke as well.
If I elect to go 408 (3.75"stroke) how do the additional cubes and change in stroke affect the value I select as my IVC?
I would like to retain the same peak HP rpm and cam accordingly.
I notice the 364/6.0liter blocks which are only a wider bore peak at a lower rpm than a 346/5.7 for the same camshaft values. Now, I am changing the stroke as well.
03-25-2013, 12:22 PM
#2
The larger cubes eat up the extra duration of a larger cam pretty quickly. So you can run a lot larger cam in a bigger motor and still have good street manners.
For instance I had a 238/242 in my stock cube 346 and it was fun, but a bit on yhe big side for daily driving. I pulled this cam out and put it in my 408 when I got it and the bigger motor had about the same street manners as a 346 with a 228/230 cam shaft.
Not sure if there is a true formula out there, but going from a 346 to a 408 is say you need about 10 degrees more duration on your cam to keep the power in the same rpm range that you had with the smaller motor.
Also when going with a big cam yiu can and want to look at your dynamic compression...I'm sitting at 12.5:1 static compression, but my cam drops me down to a pump gas friendly 8.22:1 dynamic compression.
I'm running a 255/271 .624/.624 115lsa cam in mine with an occur point of 85 degrees and it has a decent but rough idle set at 850-900 rpms
For instance I had a 238/242 in my stock cube 346 and it was fun, but a bit on yhe big side for daily driving. I pulled this cam out and put it in my 408 when I got it and the bigger motor had about the same street manners as a 346 with a 228/230 cam shaft.
Not sure if there is a true formula out there, but going from a 346 to a 408 is say you need about 10 degrees more duration on your cam to keep the power in the same rpm range that you had with the smaller motor.
Also when going with a big cam yiu can and want to look at your dynamic compression...I'm sitting at 12.5:1 static compression, but my cam drops me down to a pump gas friendly 8.22:1 dynamic compression.
I'm running a 255/271 .624/.624 115lsa cam in mine with an occur point of 85 degrees and it has a decent but rough idle set at 850-900 rpms
