Help with choosing engine and frame ('70 C10)

[_ABC_]

Hello, I bought a 1970 chevrolet c10 a year ago. It is a long wheel base with a 350 engine and automatic transmission with no power anything and drum brakes. It is not in working order so I would like to take it apart to build what I want the truck to be. I eventually plan to make it into a pro touring/daily driver, but for now I plan on making it into a daily driver for the spring and summer (so I would like to have updated suspension and power brakes/front disc brakes and power steering), that gets good gas mileage like 25 mpg for city driving and higher for highway(so engine has to be good on gas and I will try to save weight in some areas) and has enough power, and plan on shortening the frame to a short wheelbase version, and eventually want to put a 5 or 6 speed manual transmission into it. I do not plan on hauling heavy trailers or using it for other heavy duty purposes as I have another truck for those jobs. I just want this to be a daily driver that gets good mileage and has enough power to drive and overtake cars on the highway. I know it will be tough but I am up for the challenge.

So 1) I need to decide on whether to keep the existing frame and cut it shorter OR find a newer frame such as one from a used 1/4 or 1/2 ton chevy truck/suv (that already has newer suspension, power steering and brakes). So any thoughts on whether to keep and cut up the old frame and upgrade/update its suspension and braking components? Or find a newer used frame with newer suspension etc. and just shorten it? If I were to use a 1998 gmc jimmy suv frame would it be able to support a 1970 body on top of it?(I looked up the length and I would need to extend it for this application). Also would a newer frame be a lot heavier and not worth it if I am trying to save weight to increase mpg?

AND
2) I need an engine SMALLER than a 8 cylinder and 3.8 litres (and probably not going with a chevrolet engine as fuel efficiency is my biggest goal). So inline 6 and v6's come to my mind, but I do not know of any that would be fuel efficient enough to get 25 mpg city. So I started thinking of 4 cylinders. Chevrolet makes a 2.0L turbo 4 cylinder that makes 272 hp and 295 lb-ft torque. Would an engine like this be powerful enough to put in my truck? Or should I look for something like a 3.0 litre 4 cylinder engine something like a 2JZ or a RB24 (I really like these options but do not know what mpg they would achieve), etc?

Any help or advice would be helpful. I do not expect crazy good mpg, like plus 30, but am striving for 25 mpg for city driving as that is where I drive mostly.

Thanks again, and sorry for the long post!

[Overdriven]

On this forum there are users that have swapped in frames from newer trucks, suv's and vans. From my limited research the Chevy Tahoe wheelbase is closest to that of a short wheelbase c10. But those are almost exclusively 4wd adding weight and killing mpg. In my opinion your best bet for a newer frame swap is probably an extended cab or long wheelbase 2wd truck. The frame will be too long but you can just shorten it to match your c10. Gmc Jimmy is the S10/s15 which is mid size not the full size. I wouldn't recommend it based solely on the brakes being smaller than those on full size trucks. Finding parts to lower and make a newer 2wd Silverado handle would be easier than for the Jimmy as well.

You do realize that a frame swap is an intensive thing right? Tv and YouTube make it look easy and it's not all that hard, but it is time consuming. I think the quickest I've seen one done on the forums that wasn't a pro shop took over 6 months and that guy worked fast.

[_ABC_]

Hello, thank you for replying so quickly! I know that frame swapping is a long process and I do not plan to have it done in less than 6 months or even close to that. I have been looking through the different posts for a while now and have come across the 50's and 60's chevy's with s10 frame swaps and a few of the 2003-06 1/2 ton and 3/4 ton frame swaps that look really cost effective when it comes to upgrading suspension, etc. I have not been able to find any 67-72 chevy's with s10 frame swaps so I began to think it hasn't been done for a reason (like you said, they are made for light duty 1/4 tons, not full size 1/2 tons). I think my best bet would be to find a newer full size 1/2 ton short wheelbase 2wd truck as to minimize customization, or a tahoe or ext cab truck like you said.

[wbc409]

The biggest hurdle for fuel mileage is weight and the truck is a brick. Zero aerodynamics. If you go with to small of an engine, it has to work to hard to move the weight and mileage suffers. The best combination of performance and mileage is probably the ls platform.

There are several threads on here about shortening the frame, which is the route I would go with. The truck arm suspension handles well. There is plenty of aftermarket support for these trucks. Just plan out your budget.

[Overdriven]

As far as mpg. I'm not going to say it's impossible, but it's not going to be easy and I think you need to lower your expectations. C10's are shaped like bricks and weigh at least 3600lbs with no power options or ac. You also want power to go along with your mpg goal. Simply lookup the EPA mpg ratings for various vehicles rear wheel drive vehicles to put things in perspective.

My best suggestion would be the V6 and matching transmission that comes in the new Camaro. Match the rear gear ratio as best you can and you should be close to the Camaro's original mpg rating. Next best bet would be 4.8 or 5.3 LS with 6l80e trans but the best you could hope for with that is probably around 18mpg.

2jz, RB, turbo 4cyl may sound interesting but I have my doubts they'll achieve your goal. For work I went from a 4.3 v6 van to one with a 4.8 LS v8 and had mpg improve dramatically. Yes it's a more efficient engine but also with more torque and power requiring less throttle input to accelerate at the same rate. Less throttle = better mpg. Turbo needs premium fuel so any gains in mpg are offset by the increased cost of higher octane. Besides roots supercharged engines have better efficiency at the lower rpms of city driving than turbo. So if you're willing to go with premium fuel a supercharger will get better mpg than a performance turbo setup (like 2jz, RB) especially if it has a bypass valve.

[_ABC_]

Thanks for the replies, I hear what you guys are saying about the mpg and all the weight increasing luxuries that I would like on my truck. I was looking at the new 4.3 L chevrolet ecotec3 engine for the longest time but would like to get better city mpg than 18 mpg. Let's say I were to lower my expectations to 22mpg city (or at least 20mpg city), would you guys suggest this or any other 6 cylinder engines(or gear ratios for rear ends to increase city mpg but still be good on the highway for out of town trips)? I heard a lot about ls options (especially lightweight aluminum ls engine/engine parts), I have a '06 silverado with the 5.3 but I can't stand the mpg it gets to use it as a daily driver.
Thanks again for all the replies. I am still doing research and trying to figure out what my best options are. None of the specifications I have listed are set in stone and I realize only so much is possible when it comes to increasing mpg of a truck.

[_ABC_]

Oh, and if I were to go with a newer frame, I would use one from a salvage yard to save money ( I would make sure that it has not structural problems aswell).

[Overdriven]

Back to frames for a second. I agree with wbc409, I wouldn't discount using the original frame as the truck arm suspension is quite good with plenty of options out there to make it better. I've considered doing a frame swap myself but newer trucks use leaf springs and I don't want to go through all that work to end up with leafs.

But it's your truck, your $. Buying a newer truck and using the frame with drivetrain may be better for your goals and budget.

[garyd1961]

Personally I would forget about getting more than 20 mpg. You probably could get that with a well tuned vortec 350 and maybe better with a factory fuel injection and the right gears.
On the other hand I've heard diesels get good mileage.

[_ABC_]

Thanks for the reply. I'm starting to think I might have to forget about over 20mpg the more I look around on the internet. I'm not sure I want to go the diesel route for this truck. Basically I just want to short the truck, and put a decent engine and get decent mpg in it so I can drive it around until later in life when I can really turn it into a my dream truck.
Sorry for the original post if my expectations for mpg were too high. Now at least I have narrowed my frame options down to using the original and upgrading suspension parts, or finding a newer truck frame from salvage to shorten and custom fit body mounts, etc.

[wbc409]

With the increased popularity of these trucks suspension companies have started offering a lot more products to upgrade these vehicles. Do some research, figure out what fits your budget and handling goals. The only thing limiting you with these trucks is your imagination and wallet.