77crewcab
1/2 ton status
Delete
Last edited:
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.
Delete
- Thread starter 77crewcab
- Start date
Sounds like you answered your own inquiry. A diesel would fit nicely with those requirements.
77crewcab
1/2 ton status
Well I am sort of leaning towards a diesel since I am a diesel mechanic by trade. Yet the power of the 383 and 454 would be nice too. On the other hand I am not trying to make a hotrod out of a 5-6K lbs truck. I have almost all the stuff for the 383 TPI, I have a good 454 core with 781 heads. I would have to find the diesel stuff. So it is a bit of a fork in the road, use what I have or look for all new stuff. Thats why I did the poll, to try and get some input from others and see what comes out on top.
GsxrMike
1/2 ton status
If you have to find the diesel stuff anyway just drop in a D-MAX or 12 valve cummings! Now that would be sweet!
jhellwig
1/2 ton status
You gotta pick one. Mileage or Power.
77crewcab
1/2 ton status
Well that is the hard part. Power or Mileage? Honestly I am pretty happy with the 350/700 combo in my burb. Sure it could lose a little a little more umph! but I don't really have any complaints for daily driving. Pulling my camper every once in a while makes me wish for some more power. But I also realize that the 350 is a little tired and I figure it would do better in the K5 anyway with the weight difference from burb to K5. The bigest complaint is the mileage. I figure that the 383TPI or the 454 would probably do better in the mileage due to better low to mid range torque. But I know it wont do as well as a diesel. From what I have read on the 6.2/6.5 and 4BT I would probably be happy with the power they put out and the mileage is better. From what I have looked at in a K5 I should be able to get about 15mpg with the gassers and about 20-25 with the diesels and a little less power. If I could get the diesels up to say 250 horse that might be the perfect compromise.
77crewcab
1/2 ton status
Well I think I am narrowed down to either the 6.2/6.5 or the 383TPI (basically this engine with TPI injection (http://www.sdparts.com/product/12499101/HT383PerformanceCrateEngine340HP435ftlbs.aspx)
The 454 I don't think would ever get the mileage I am hoping for. The 4BT is a possibility but the fact that the 6.X is a strait bolt in makes it take a slight lead.
My biggest thought is that I have everything plus some extra parts for the 383, just have to finish assembling it. The diesel I would have to start from scratch. I know the power would be more with the 383, but what would the mileage be like. If I could get the diesel to 200-250 hp what kind of torque would I be looking at? I would run a turbo on either of the diesel options. One thing I have thought about is just keeping the 700R4, but if I do that what would I need to do to beef it up for the 383 and/or for the 6.X?
The 454 I don't think would ever get the mileage I am hoping for. The 4BT is a possibility but the fact that the 6.X is a strait bolt in makes it take a slight lead.
My biggest thought is that I have everything plus some extra parts for the 383, just have to finish assembling it. The diesel I would have to start from scratch. I know the power would be more with the 383, but what would the mileage be like. If I could get the diesel to 200-250 hp what kind of torque would I be looking at? I would run a turbo on either of the diesel options. One thing I have thought about is just keeping the 700R4, but if I do that what would I need to do to beef it up for the 383 and/or for the 6.X?
Thunder
3/4 ton status
If you want brute power and good gas mileage. I would build 383 and put a set of ported 193 TBI heads on it and go with TBI fuel injection with 46 MM bored TB roller cam and custom chip. It will give more power and torque than a stock TBI 454. Plus the good MPG of a TBI 350.
roadnotca
3/4 ton status
You want to get good MPG from a brick
?
Go the 383.
? Go the 383.
Last edited:
250 straight six!
77crewcab
1/2 ton status
See it is kind of a toss up between the 383 or 6.X. Any one running an injected 383 that can share there mileage numbers. I know the 6.x will get the mileage/power I want. I know the 383 will get the power I want but the big deciding factor is the mileage of the injected 383.
K5dreamer
1/2 ton status
well, my TPI350/700R4, in a 3600lbs camaro with good aerodynamics gets around 24mpg on the highway. gas engines being air throttled as they are, i really cant see a 5-6000lbs truck with the aerodynamics of a brick getting close to that especially with an extra 33in of displacement.
my 6.2L diesel truck, with a 3 speed non overdrive, 3.08 gears, and 33in tires, gets at least 20mpg and usually 21 or 22 mpg if i really behave myself. regarding power, ive never really understood the need for fast lifted trucks. my truck has plenty of oomph to pull out into traffic, and accellerate smoothly off an onramp onto the highway, and cruises quite nicely at 55-65mph on long drives. It also has had more than enough power for wheelin (granted i dont do anything really crazy) but i have yet to run into a hill or obstical that i couldnt overcome, even if i had to drop into 4 low to do it.
having both engine setups, i strongly reccomend the diesel for your swap. You might want to look at the optimizer 6500, 205hp and 440ft/lbs of torque, if i was looking to start from scratch, thats probly the route i would take.
http://www.optimizer6500.com/default.asp?section=product_description
my 6.2L diesel truck, with a 3 speed non overdrive, 3.08 gears, and 33in tires, gets at least 20mpg and usually 21 or 22 mpg if i really behave myself. regarding power, ive never really understood the need for fast lifted trucks. my truck has plenty of oomph to pull out into traffic, and accellerate smoothly off an onramp onto the highway, and cruises quite nicely at 55-65mph on long drives. It also has had more than enough power for wheelin (granted i dont do anything really crazy) but i have yet to run into a hill or obstical that i couldnt overcome, even if i had to drop into 4 low to do it.
having both engine setups, i strongly reccomend the diesel for your swap. You might want to look at the optimizer 6500, 205hp and 440ft/lbs of torque, if i was looking to start from scratch, thats probly the route i would take.
http://www.optimizer6500.com/default.asp?section=product_description
My motor is in the mid-teens, I've got some tuning to do.
I don't think I'd choke a 383 with TPI. Some will disagree I know, but my personal opinion is that TPI was designed around the 305, is marginal on a stock 350, and anything larger is very limited by the hard parts.
I vote for diesel, although with the price of diesel anymore, I'm not sure if the economy savings are still there.
I don't think I'd choke a 383 with TPI. Some will disagree I know, but my personal opinion is that TPI was designed around the 305, is marginal on a stock 350, and anything larger is very limited by the hard parts.
I vote for diesel, although with the price of diesel anymore, I'm not sure if the economy savings are still there.
Thunder
3/4 ton status
Also with older diesel engines you have to factor in ULSD. Less power, less MPG, increased wear without additives. Additives increase the already high cost per gallon.
Because of the ULSD requirments and all the extra refining. You will never see diesel cheaper than gas again.
Unless the automotive industry switches from gas engines to diesel in the coming years to get their CAFE standards to comply.
Because of the ULSD requirments and all the extra refining. You will never see diesel cheaper than gas again.
Unless the automotive industry switches from gas engines to diesel in the coming years to get their CAFE standards to comply.
Leper
1/2 ton status
Stick with gas. You need 2 vehicles. One with power and one with good mileage
where is the option for a 632 BIG CHIEF PRO STOCK MOTOR? j/k man, I would go the 383 route. Not the weight of a BB but still plenty of torque. Any V8 other then a stock one is not going to be good on gas, you have to choose one over the other.
j/k man, I would go the 383 route. Not the weight of a BB but still plenty of torque. Any V8 other then a stock one is not going to be good on gas, you have to choose one over the other.
x2.250 straight six!
77crewcab
1/2 ton status
Well I think I made up my mind today to at least try the 383 since I am so close to being done with it. If after driving it some, I am not satisfied then I will look at a 6.x turbo swap. I mainly figure that for all the work I have already put into it, it would be foolish to toss it out the window without even trying it.
Thunder
3/4 ton status
I am not trying to tell you what to do. But. If gas mileage is your goal. I would build a 383 TBI engine.
The best heads for what you want are TBI heads. Depending on the pistons you use. Either 193 64cc heads for dished pistons. Or 191 76cc for flattop pistons. IMO for gas mileage I would use dished pistons and 193 heads. Both combos will give a compression ratio around 9.3. to 1. But i think dished pistons work better with the swirl ports for fuel economy.
TBI heads because of the swirl port design will give you more lowend torque and MPG than any other head (Even Vortecs) You will loose a little power on the top end over 3800 rpm compared to Vortecs. But unless built for it, a basic 383 is not good for revving over 5K anyhow.
The heads should be worked over of course. 3 angle valve job, Better springs to match the cam you use. Mild porting would be good too. Simple gasket match and cleaning up the intake and exhaust runners is enough.
As for cam. Pick a high torque low RPM idle to 4800 RPM computer friendly gas mileage/ RV cam.
For gas mileage. Keep the stock 42mm TB or get a small bored 46mm stock GM TB.
Resist the temptation to go with a BBC or Holley TB.
You will end up with an engine putting out around 280 HP and 380 or so torque. And get the same or slightly better MPG as a stock TBI 350.
Depending on the cam, This combo should run on a stock chip. If you use 350 injectors and up the fuel pressure.. But a custom chip is highly recommend for the best performance.
For comparison a TBI BBC= 230 HP 385 TQ 12 MPG tops
The best heads for what you want are TBI heads. Depending on the pistons you use. Either 193 64cc heads for dished pistons. Or 191 76cc for flattop pistons. IMO for gas mileage I would use dished pistons and 193 heads. Both combos will give a compression ratio around 9.3. to 1. But i think dished pistons work better with the swirl ports for fuel economy.
TBI heads because of the swirl port design will give you more lowend torque and MPG than any other head (Even Vortecs) You will loose a little power on the top end over 3800 rpm compared to Vortecs. But unless built for it, a basic 383 is not good for revving over 5K anyhow.
The heads should be worked over of course. 3 angle valve job, Better springs to match the cam you use. Mild porting would be good too. Simple gasket match and cleaning up the intake and exhaust runners is enough.
As for cam. Pick a high torque low RPM idle to 4800 RPM computer friendly gas mileage/ RV cam.
For gas mileage. Keep the stock 42mm TB or get a small bored 46mm stock GM TB.
Resist the temptation to go with a BBC or Holley TB.
You will end up with an engine putting out around 280 HP and 380 or so torque. And get the same or slightly better MPG as a stock TBI 350.
Depending on the cam, This combo should run on a stock chip. If you use 350 injectors and up the fuel pressure.. But a custom chip is highly recommend for the best performance.
For comparison a TBI BBC= 230 HP 385 TQ 12 MPG tops
