BBC question

[dfarr67]

Theoretical question.

Years ago moved from a 355 to a 383 in a '89 K1500, it has a form of TPI with bank to bank EFI, haven't crunched any numbers but the impression is fuel mileage is very competitive with the 355- improved torque is noticeable with a good tune as the trans does not shift down as readily on the hills oe 700R4/3:73.

Had another 355 that I sold awhile back, was offered a mild 454 on trade.....wondering what if...? assuming competent street hyd roller cam and I would use AFR oval port heads (or competitive alum head), how would the efficiency compare with the existing AFR vortec 383, prefer not to take the hp penalty of a 4L80E, this is also assuming that the 700 I had built years ago and has held out to some abuse- but I respect that it is on the weaker side (talking engine here- NOT trans choice).

Maybe a 402? Not terribly familiar with BBC and not sure if I want to discuss non stock strokes (destroked).

Are the BBC best left to competition and towing and not suited for DD ?

[FC-Pilot]

Having had a 454 in a crew cab dually as a DD, I would first ask are your expectations realistic? It is going to use more fuel, PERIOD. Now, if you can keep your foot out of it and drive like a grandma for most of your driving you will be just fine. My truck was an old 1976 with a turbo 400 and holley carb. I would get 13-14 in town driving. Sadly on the highway, I got the same. if anyone else borrowed my truck they would never get better than 10 MPG. Driving style is your friend or enemy. Now it sure was nice having the extra torque when I had to hook up a trailer. During those times I did not care about fuel mileage as much as getting a job done.

If I were in your shoes and your commute is 30+ miles a day, I may pass. If 20 or less I might look at making the jump. And if doing EFI and playing a little with the rebuild I think you could surprise some people with fuel mileage numbers.

As a side note, if I were in your shoes I would not play with the smaller BBC unless that was what you had. With the extra weight penalty that they are I would just go for the 454 and set it up for efficient power instead of huge torque and HP. I have never been impressed with smaller cube big block chevy’s unless in an application built for max power.

Paul

[prairiehotrodder]

i definitely wouldn't want to daily drive a big block chevy. If you want to swap in something i would go to an LS without hesitation. The newest 5.3 or 6.0L that you can find. Use the Fitech swap harness and their drive by cable throttle body. If you could get a 2014+ with direct injection that would be the best in my opinion. My daily driver is a 2015 silverado and they are great motors.

[mag2555]

In a general way, fuel mileage wise you will find this, since the 454 has 18% more cid it needs to make more then 18% more torque in the ball park of your trucks normal cruse rpm, this will allow you to turn less rpm and have break even point in terms of fuel mileage.

[bobmc]

look at the dyno graphs in the Chevy Performance Parts catalog, the high torque 383 makes about 105 hp @ 2000 rpm, the lowest power 454 makes about 185 hp @ 2000 rpm, thats 80 hp increase for about 150 pounds weight increase

[1980RS]

look at the dyno graphs in the Chevy Performance Parts catalog, the high torque 383 makes about 105 hp @ 2000 rpm, the lowest power 454 makes about 185 hp @ 2000 rpm, thats 80 hp increase for about 150 pounds weight increase

No 383 is going to beat a 454 peanut port head below 3500 RPM, that where that BBC does it's best. I always remember my buddies with their 6.5 turbo diesels tell me how they were going to out pull my 454 Suburban going up hills. I would just destroy those POS, took out many a ford turbo truck too. I am sure the 4.56 gears might have had something to do with that.

[dfarr67]

i definitely wouldn't want to daily drive a big block chevy. If you want to swap in something i would go to an LS without hesitation. The newest 5.3 or 6.0L that you can find. Use the Fitech swap harness and their drive by cable throttle body. If you could get a 2014+ with direct injection that would be the best in my opinion. My daily driver is a 2015 silverado and they are great motors.

My work truck is a 2019 K1500- engine is fine- starting to get a hate on for the trans tho.

[mag2555]

We’ll keep in mind that although it sounds steep 4.56 gears along with the common height tires used on pickup trucks is like having rear gears in the 3.23 range with passenger car tires these days!

A Diesel is always lugging around 300 extra lbs of itself also.

[dfarr67]

I love diesel, but I would not put the miles on to make it worthwhile, don't tow enough, this climate is COLD, and wouldn't want a modern one off warranty. BBC would be cheaper all around- even fuel here for diesel is more expensive.

[Roadknee]

My work truck is a 2019 K1500- engine is fine- starting to get a hate on for the trans tho.

Is that the 8 or 10 speed? What’s going on with it?