fuel economy
11-22-2018, 11:19 AM
#1
fuel economy My daily driver is a 1963 Pontiac Catalina convertible. I decided to jump back into the deep end after being away from automobiles for close to 35 years. The issue is this, this will probably be my last car as I do not believe I have another build left in me. I love the car but 11-13 MPG is getting old on $4 gas, at least that is what they call the swill they pump here in So Cal.
The logical solution seems to be an LS conversion so I am presently looking for a salvage chev/gmc cargo van with the 5.3 and 6 speed auto, they are cheap and engine swaps are always easier if the donor vehicle is available. If there is a better combination I am open to any and all suggestions. The plan is to go through both engine and trans before the swap so hopefully I will not need to do either one again. I am too damn old for jack stands and a creeper and being retired I have a lot more time than the money to have someone else do it for me.
Almost all of the vans I have found have the 4.6 in them but apparently the difference is the stroke length and since the engine will undergo a complete overhaul getting a 5.3 crank is easy.
Now we get into the reason for the thread, the rebuild. It is an open slate. Ideally I would like to stay with 87 octane but if a jump to the 93 will deliver better results it is not out of the question. For instance my '94 GMC 1500 4wd gets around 13-14 in town and maybe 16-17 on the road on 87 while a Corvette apparently is capable of 35 on the road and my guess is that it requires the higher octane. Obviously there is a HUGE difference in weight and wind resistance but if I give away 10 mpg to wind resistance that is still twice the mpg I am presently getting. Also only half the battle is the right selection of hardware, the other half is the tuning. The last mileage build I did was a gen 1 small block in a '65 Nova. Dual points and an A series Carter AFB, (19 in town and 29 on the road) not a lot of technology. Now I need to worry about electrons running through the sand, a whole different issue. I am guessing that there are programs available for the laptop that will address the issue so which one is the best and where do I find information on programming as this is a whole new issue for me because there are a lot more parameters available than just timing curve and afr.
I am getting serious about this because a friend and I will probably enter the great race, next year it is starting about a hundred miles from my house and going all the way up Tacoma Wa. It would be nice to have a modern running gear for the trip not to mention the gas bill.
Any information I can get would be appreciated more than you know
The logical solution seems to be an LS conversion so I am presently looking for a salvage chev/gmc cargo van with the 5.3 and 6 speed auto, they are cheap and engine swaps are always easier if the donor vehicle is available. If there is a better combination I am open to any and all suggestions. The plan is to go through both engine and trans before the swap so hopefully I will not need to do either one again. I am too damn old for jack stands and a creeper and being retired I have a lot more time than the money to have someone else do it for me.
Almost all of the vans I have found have the 4.6 in them but apparently the difference is the stroke length and since the engine will undergo a complete overhaul getting a 5.3 crank is easy.
Now we get into the reason for the thread, the rebuild. It is an open slate. Ideally I would like to stay with 87 octane but if a jump to the 93 will deliver better results it is not out of the question. For instance my '94 GMC 1500 4wd gets around 13-14 in town and maybe 16-17 on the road on 87 while a Corvette apparently is capable of 35 on the road and my guess is that it requires the higher octane. Obviously there is a HUGE difference in weight and wind resistance but if I give away 10 mpg to wind resistance that is still twice the mpg I am presently getting. Also only half the battle is the right selection of hardware, the other half is the tuning. The last mileage build I did was a gen 1 small block in a '65 Nova. Dual points and an A series Carter AFB, (19 in town and 29 on the road) not a lot of technology. Now I need to worry about electrons running through the sand, a whole different issue. I am guessing that there are programs available for the laptop that will address the issue so which one is the best and where do I find information on programming as this is a whole new issue for me because there are a lot more parameters available than just timing curve and afr.
I am getting serious about this because a friend and I will probably enter the great race, next year it is starting about a hundred miles from my house and going all the way up Tacoma Wa. It would be nice to have a modern running gear for the trip not to mention the gas bill.
Any information I can get would be appreciated more than you know
11-22-2018, 03:05 PM
#2
TECH Senior Member
Even with today's gas (I'm in California too...) you can run 10:1 compression, which is about what the 5.3 you mention has (about 9.9:1). Most 1500 Chevy/GMC pickups. will have the 5.3 in it so you don't need to modify a 4.8. Plus most of them have the 4L80E tranny behind them, which is VERY durable.
11-23-2018, 11:14 AM
#3
I am looking for a salvage van because they are a lot cheaper than a truck. I have only found one within a reasonable distance of my house that had other than the 4.8 and it was a 6.0 which I believe would be counter productive. Also I was thinking about the 6 speed, the low gear should help getting that plug moving in LA traffic, plus the higher overdrive should help with light throttle cruising on flat ground.
My issue is that I know nothing about the LS engine. The closest I have gotten to one is changing the oil and the fuel pressure regulator on my GMC 1500. I probably could still tell you what combination of parts you will need to accomplish your objective with a gen one but will need to borrow that knowledge to build the 5.3. And the tuning issue, I presently have a Holley Sniper on the Pontiac, long story why, and I keep making small changes in an attempt to dial in some economy. I have managed to get the freeway mileage up to around 16-17 but in town is 11-12 on a good day and it will not budge above that. I am doing this with the hand held tuner which is something less than desirable for the job. An actual computer program will probably give more information to reach the desired objective once I learn how to interpret it. I never did like school and here I am probably going back.
The today's gas you are referring to would that be the 87 octane? The 389 presently in the Indian is running 10.25 (stock CR) and it does not even like the 93, I have to be very careful with the timing to keep it from pinging when it shifts into 2nd gear. It has the Roto-hydro in it and the 1-2 shift normal driving lugs the engine pretty bad. The roto-hydro has to be the worst attempt ever to come out of the Hydramatic division.
My issue is that I know nothing about the LS engine. The closest I have gotten to one is changing the oil and the fuel pressure regulator on my GMC 1500. I probably could still tell you what combination of parts you will need to accomplish your objective with a gen one but will need to borrow that knowledge to build the 5.3. And the tuning issue, I presently have a Holley Sniper on the Pontiac, long story why, and I keep making small changes in an attempt to dial in some economy. I have managed to get the freeway mileage up to around 16-17 but in town is 11-12 on a good day and it will not budge above that. I am doing this with the hand held tuner which is something less than desirable for the job. An actual computer program will probably give more information to reach the desired objective once I learn how to interpret it. I never did like school and here I am probably going back.
The today's gas you are referring to would that be the 87 octane? The 389 presently in the Indian is running 10.25 (stock CR) and it does not even like the 93, I have to be very careful with the timing to keep it from pinging when it shifts into 2nd gear. It has the Roto-hydro in it and the 1-2 shift normal driving lugs the engine pretty bad. The roto-hydro has to be the worst attempt ever to come out of the Hydramatic division.
12-07-2018, 10:09 AM
#4
TECH Fanatic
I think you will enjoy the new setup in the '63, but it will take a lot of fuel usage to make up the fuel cost savings. What a cool cruiser ! You also might want to consider having a professional do the tuning as they will be able to tune the engine and transmission to work together to achieve your goal for the same cost or less than you can purchase the software and learning it all.
I think your project is a very cool one, good luck with the donor search.
I think your project is a very cool one, good luck with the donor search.
12-08-2018, 08:22 PM
#5
It will probably cost me abut 3k plus depending on what I need to pay for the donor vehicle. Fortunately I am not in a particular hurry so I am checking on erepairables quite frequently looking for a really bad wrecked chev or gmc pickup '14 or newer. The research I have done would indicate that my best bet is the LT with direct injection. The initial cost will be higher but if I can find one with reasonable mileage I will not need to overhaul anything just put it in and connect everything up, and then obviously tune it. Which for a guy that grew up in the 50's working on cars and did it professionally from the early 60's to the late 80's tuning carries a completely different mental picture.
As for the cost benefit ratio, this will probably be my last car, as I do not think I have another build left in me, and if I live up to my genetic profile I will be driving it for another 15+ years. Going from the 93 octane to the 87 and with any luck increasing the fuel economy dramatically I will probably pay for the change many times over.
Now the driveability, if you have never driven one of the roto-hydro's it is an experience in LA traffic. The transmission has no torque converter. In first gear there is a small, about 7 or 8 inch fluid coupling, that allows the engine to spin when the vehicle is stopped. First gear has around a 2.8 gear ratio and adding in the slippage of the fluid coupling in reality the first gear ratio is around 3.0. second gear is a solid connection between engine and driveshaft like a stick shift and the second gear ratio is around 1.5. So you get this plug moving and it shifts into second dropping the engine rpm in half. In city traffic that means that the engine is going from around 16-1800 rpm down to 8 or 900 and going from a fluid coupling to a solid connection through the trans. Now reverse that in stop and go freeway traffic, slow down to where the engine is being pulled down to almost idle with a solid connection through the trans and then the traffic starts to move again. So you step on the throttle and the increased throttle pressure in the trans kicks it back into first gear the engine spools up to around 1800 rpm catching up with the dramatic increase in gear ratio and filling the fluid coupling and then within 40 feet shifts back into second lugging the engine. The slim jim, as it was affectionately referred to in the day, was the worst transmission ever to come out of the hydramatic division but as it was designed in the 60's no telling what they were smoking.
Bottom line is that if I get no increase in fuel economy at all the increased driveability will be worth it. Plus I will at least be back to 87 octane and have a drive train that I will be able to get parts for 15 years down the road. Remember they quit building Pontiacs.
As for the cost benefit ratio, this will probably be my last car, as I do not think I have another build left in me, and if I live up to my genetic profile I will be driving it for another 15+ years. Going from the 93 octane to the 87 and with any luck increasing the fuel economy dramatically I will probably pay for the change many times over.
Now the driveability, if you have never driven one of the roto-hydro's it is an experience in LA traffic. The transmission has no torque converter. In first gear there is a small, about 7 or 8 inch fluid coupling, that allows the engine to spin when the vehicle is stopped. First gear has around a 2.8 gear ratio and adding in the slippage of the fluid coupling in reality the first gear ratio is around 3.0. second gear is a solid connection between engine and driveshaft like a stick shift and the second gear ratio is around 1.5. So you get this plug moving and it shifts into second dropping the engine rpm in half. In city traffic that means that the engine is going from around 16-1800 rpm down to 8 or 900 and going from a fluid coupling to a solid connection through the trans. Now reverse that in stop and go freeway traffic, slow down to where the engine is being pulled down to almost idle with a solid connection through the trans and then the traffic starts to move again. So you step on the throttle and the increased throttle pressure in the trans kicks it back into first gear the engine spools up to around 1800 rpm catching up with the dramatic increase in gear ratio and filling the fluid coupling and then within 40 feet shifts back into second lugging the engine. The slim jim, as it was affectionately referred to in the day, was the worst transmission ever to come out of the hydramatic division but as it was designed in the 60's no telling what they were smoking.
Bottom line is that if I get no increase in fuel economy at all the increased driveability will be worth it. Plus I will at least be back to 87 octane and have a drive train that I will be able to get parts for 15 years down the road. Remember they quit building Pontiacs.