Randy67
07-11-2012, 05:54 AM
Basically I am wondering about the feasibility of boosting my 350 in my 79 GMC Dually standard cab longbed. I am towing a 28ft Horton enclosed v-nose trailer with this truck and would like to improve its power. Either that or would an engine swap be a better choice. Here is the truck and trailer I am dealing with:
https://static1.pt-content.com/images/noimg.gif
The 350 does a decent job but does struggle a bit on hills. The truck has the SM465 transmission along with 3.73 gears. Truck weights 5400 lbs, trailer is probably 8 to 9000 lbs loaded (GWR is 10K), haven't had a chance to weight it yet.
I am looking for improvement in the idle to 4500 rpm range, currently it tows best at 2800-3000 rpms, which is 65-70 mph per GPS. No plans for an overdrive yet as the 350 just won't pull the trailer in OD. Here are the options I have currently see:
1. Supercharger, either a roots style which would give good low end power, or a Centrifugal style, which would probably work better in midrange.
2. Turbos. This interests me, but could end up being a more expensive build. I believe it would give me the best towing power for a gas engine, but I could be wrong.
3. Throw in the towel and put a BBC back in the truck, it originally was a 454 before I got it. I helped my buddy I got the truck from swap it to a small-block, he was looking for better mileage and wasn't towing heavy stuff. He suggested a 402, to get more power without totally killing the gas mileage.
4. Swap in a late model Diesel, Duramax or Cummins. This would be my favorite, but it would be cheaper just to sell my truck and buy a Diesel truck.
For the sake of this discussion only, swapping an LS motor is not in the mix. Again, at this point it would be better to just get a newer truck with a 6.0 or 6.2L. I do enjoy the cheap tag and insurance on the 79.
The one thing I do worry about boosting the SBC, is on long hills (like Mont Eagle in TN and hills around North GA) that the constant boost may be hard on the bottom end, leading to a short engine life. Maybe it isn't a problem, but I don't want to overlook anything. So let me know your thoughts, this isn't something I am doing anytime soon, more of a brainstorming session. Randy
https://static1.pt-content.com/images/noimg.gif
The 350 does a decent job but does struggle a bit on hills. The truck has the SM465 transmission along with 3.73 gears. Truck weights 5400 lbs, trailer is probably 8 to 9000 lbs loaded (GWR is 10K), haven't had a chance to weight it yet.
I am looking for improvement in the idle to 4500 rpm range, currently it tows best at 2800-3000 rpms, which is 65-70 mph per GPS. No plans for an overdrive yet as the 350 just won't pull the trailer in OD. Here are the options I have currently see:
1. Supercharger, either a roots style which would give good low end power, or a Centrifugal style, which would probably work better in midrange.
2. Turbos. This interests me, but could end up being a more expensive build. I believe it would give me the best towing power for a gas engine, but I could be wrong.
3. Throw in the towel and put a BBC back in the truck, it originally was a 454 before I got it. I helped my buddy I got the truck from swap it to a small-block, he was looking for better mileage and wasn't towing heavy stuff. He suggested a 402, to get more power without totally killing the gas mileage.
4. Swap in a late model Diesel, Duramax or Cummins. This would be my favorite, but it would be cheaper just to sell my truck and buy a Diesel truck.
For the sake of this discussion only, swapping an LS motor is not in the mix. Again, at this point it would be better to just get a newer truck with a 6.0 or 6.2L. I do enjoy the cheap tag and insurance on the 79.
The one thing I do worry about boosting the SBC, is on long hills (like Mont Eagle in TN and hills around North GA) that the constant boost may be hard on the bottom end, leading to a short engine life. Maybe it isn't a problem, but I don't want to overlook anything. So let me know your thoughts, this isn't something I am doing anytime soon, more of a brainstorming session. Randy