Engine Upgrade

[87blackblazer]

In the coming months, I want to work on the engine (and maybe tranny). I want to have something that maintains decent low-end torque, gets mediocre fuel economy, can four-wheel, and can tow a ski boat (approx. 3800 lbs.). Since I'm in CA, I have to worry about smog. Here are what I'm thinking about:

rebuild/upgrade original
buy crate 383 TBI
LM7 4L60E swap
LQ4 4L80E swap

Assume that I would not make mods (other than required for swap) to anything but the rebuilt original. Also, assume that $$ is not a driving consideration.

Based on my understanding of the CA smog laws (referee, swap, etc.), the toughest one might be the 383 crate. All others would be legal assuming that I maintain all emissions and sensors from the donor vehicle.

What would you do?

 

[76zimmer]

I vote 350 just cuz of the ease of repair. 6.0 with 4L80 would be sweet, but would also require you to meet that year of engine regs.

 

[87blackblazer]

The engine regs wouldn't really be a problem if I used all of the original sensors and emissions components. At least not in my estimation. No matter what I do, I can't remove any sensors or emissions devices from the motor that I'd use. I think the the biggest issue w/ the LSx swaps would be just that - it's a swap - and all that comes w/ it.

 

[nsxxtreme]

What else have you done to the truck bigger tires? Changed axle gears? I'm in a similar situation as you I tow a 21 foot wake board boat that wieghs close to 4k lbs. My truck has 35" tires and 4.56 axle gears. I used to tow my boat with my Range Rover and it does wonderful. But I looked into the cost of a rebuilt transmission $7k and decided it would be cheaper to buy an additional truck. So I bought an 87 blazer to tow the boat and pull my dirtbikes and just to have fun in.

When I bought it the motor needed to be rebuilt so I decided to rebuild the original TBI 350. I can tell you it does not have enough power to tow a boat of that weight up any kind of incline at speed. I have to keep my truck in 2nd in order to make it up a highway hill here. If you can afford the extra cost go with a bigger motor. If I had to do it over I would at least go with a 383 but would probably opt for a 400 if I could find one.

 

[87blackblazer]

At present, I haven't done any additional mods. I'm in the planning process and plan to put larger tires. I would only change the gears as necessary.

 

[nsxxtreme]

At present, I haven't done any additional mods. I'm in the planning process and plan to put larger tires. I would only change the gears as necessary.

If you put bigger tires on you will want to change the axle gears as well if you want to maintane the same drive ratio. Which is the reason I went to 4.56 axle gears it gives me the same ratio as you with stock tires. I'd highly recommend looking into a bigger motor for what you want to do unless you enjoy driving 45 on the highway.

 

[87blackblazer]

In that case, would you go w/ the LQ4 6.0L or a 383 TBI w/ around 400 hp/tq?

 

[pauly383]

I am the lone vote for the 5.3 .

I chose that since :

you posted it , so can afford the whole swap .

Theres a bazillion wrecked in yards all over the southwest ( drunk river rats seem to total one on the way home from lakes every weekend ) .

And since its an LS based motor , getting huge power out of it is easy as pie . You can get an honest 450 hp motor out of that with a little work and select bolt ons like heads and cam , and still pass emissions .

Good article ( will tell you they changed from drive by wire to cable throttle ) http://www.superchevy.com/technical...ucp_0810_chevy_53_liter_ls_salvage/index.html

 

[dyeager535]

Yep, I'd do either that or the 6.0, assuming the 6.0 isn't much more of a hassle/expense.

You just can't make the same power out of the earlier engines as you can the later ones. If previous designs were as good, they'd still be used.

 

[87blackblazer]

Good article ( will tell you they changed from drive by wire to cable throttle ) http://www.superchevy.com/technical...ucp_0810_chevy_53_liter_ls_salvage/index.html

The power graph for the stock engine (except for water pump and headers) look really high as compared to published numbers. Certainly the headers would breath better and the water pump would decrease parasitic loss, but still? Would the minor tune that they did increase the numbers that much? Those stock numbers make the 5.3L much more appealing!