View Full Version : engine build digging.

10-21-2004, 10:54 AM
Hi all.

First off, I'm new but competent...simply need a little schooling on the 3.8's. I have looked briefly and haven't had much luck finding smaller details on engine specs.

Are the heads off the newer (99+) mustang 3.8 engines interchangable if a custom intake were to be manufactured? What is the differences on the newer 99+ heads and the SC heads that make them more powerful....because the newer 3.8(4.2) makes descent power without a power adder. I realize the higher compression and the 12 runners on the newer engine help but what are the charachteristics on teh SC engines such as the lower compressionon the SC engines? Is a larger volume in the heads or the pistons or both? Are the SC pistons forged? The crank and rods..are they different? What's the max power one can bear on a stock build? Like I said..I'm a newbie and I simply want to build the first one right. I require knowledge, technical knowlege to build something bada$$. :eek:

Thanks everyone for your help.

10-21-2004, 01:35 PM
I'm not really the right person here for 3.8L-specific questions, especially regarding the differences between the SC and Mustang V6. However, I'm fairly certain that the compression is much higher on the V6. You probably already know this, but if you don't: high compression is bad on supercharged/turbocharged engines. Basically, high compression is giving you a slight efficiency improvement at the expense of increased risk of detonation. A supercharger is giving you a huge performance improvement at the expense of the same risk of detonation.
So, let's say you're running a 9.2:1 motor for 93 octane. (Not specifically a 3.8L, or a 2.3L, or anything else, just in general.) You can probably get about 5lb of boost on there. Run the same motor at 8:1 and you can probably get 15-20lb of boost on there. Now, you may be as little as 70% as efficient, but you're packing 175% of the air in there. So you end up getting 120% of the power that you would've gotten. Now, obviously, there are both limitations and downsides -- it doesn't do you much good to run a 4:1 compression ratio, and you're going to either need a larger supercharger or need to spin it faster, either of which increase the drag on the engine.
Basically, I suspect that you'd end up with a less capable motor supercharging a new Mustang motor than you would building up the SC motor. I think you'd see detonation at lower power levels, and possibly have a less-strong engine as well. But, like I said, I'm no expert on this motor, so maybe somebody here has contradictory experience. If so, listen to them.
My apologies if this is overly pedantic. If you knew all of this already, sorry for the extra detail. If you didn't, hopefully this helps a bit.