harthoorntech

I have a 4.8 motor out of a 2000 chevy truck and I am going to be swapping it into my 98 k1500. If I were to take the crank out of a 5.3 and put it in the 4.8 with stock 862 heads what kind of compression will I be looking at? This is with the 4.8 pistons. I also want to know a good way to get right at 400hp with this motor. I will be pulling trailers with it.
Thanks for any input

JordanRN

From what I've read, the cranks are all the same between 4.8, 5.3 and 5.7. Only difference between the 5.3 and 4.8 are the pistons and rods if I remember correctly.

Someone correct me if I'm wrong!

Jordan

harthoorntech

That may be true, I honestly dont know I'm pretty new to all of this.

one fast zo6

iTrader: (490)

4.8 crank has less stroke.

pappyboost

Same bore @ 3.78
4.8 stroke is 3.267 while 5.3 is 3.622
Someone correct me if im wrong

96capricemgr

iTrader: (1)

Find a 5.3 block to start with. Wouldn't want to drag rings below the wear line in the 4.8l block

Quick Ranger

iTrader: (2)

The block is the same for 4.8 or 5.3. Crank and rods are different on the 4.8. You could use the 4.8 flat top pistons with the 5.3 crank and rods. Usually it takes compression up to 10:1 or so.

harthoorntech

Thanks, thats what I was looking for.
I won't have to worry about the wear line in the cylinders because I will have the block worked before I do anything

96capricemgr

iTrader: (1)

How are you going to bore it but still use stock pistons?

93Z2871805

iTrader: (5)

Glaze break the cylinders with a ball hone and file fit new rings. He said worked, not bored.

Worst case scenario is there's too much taper and then you just go with a stock replacement oversized piston and punch it out.

harthoorntech

I'm not planning on having it bored, when I said worked I meant what the guy above this comment said.

Paul Bell

iTrader: (9)

I would suggest you look into "newer" pistons. They are slightly larger and have coated skirts. This greatly reduces piston slap.

harthoorntech

How new do they have to be to have these pistons?

Darth_V8r

iTrader: (4)

Assuming you mean crank HP, and not wheel HP?

harthoorntech

400 crank hp max, probably not even that

Paul Bell

iTrader: (9)

There are various makers that offer coated pistons. Wiseco, J&E, Mahle....

Quick Ranger

iTrader: (2)

Speed Pro makes replacement pistons, cheap at $186 at Summit, even over sizes.

Darth_V8r

iTrader: (4)

400 on a 4.8 is a tall order, and you'd have to sacrifice torque to get there. Since you'll be pulling trailers, you can't afford to sacrifice low end torque.

Assuming you go with the 5.3 build. First, get a set of 243 or 799 heads. For reference, I've seen 4.8's with 243's outrun 5.3's with 706 heads in otherwise similar Tahoes.

Contact a vendor like Cam Motion or EPS or Tick for a drop-in cam. They're very good at developing a surprising amount of power out of some "smallish" cams. When you decide on a cam, also ask about a matching torque converter stall speed to best take advantage of the combo.

I think that's your best bet for a truck that can tow and still be fun to drive / show-off in when not towing.

harthoorntech

That was my overall plan, 5.3 with hopefully 243 heads and a good cam with a well matched torque converter.

Thanks on the input about the 243 heads also, good info.

Bilster

iTrader: (21)

As Darth_v8r suggests, if you are going to be pulling trailers, you need to consider low end torque over horsepower....especially if you are factoring in gas mileage. It's not as glamorous building a truck specific motor but you'll get some good satisfaction out of it. Here is what I did to my 5.3. I installed 4.8 pistons to raise the compression (along with honing an already low mileage motor and balancing the rotating assembly). I installed a Comp Cams truck specific cam. I had the 706 heads "truck ported". That is little attention was paid to hogging out the ports for top end breathing and more attention was paid to working the valve pockets and chamber for low lift breathing...where a towing truck mostly lives. Added headers, high flow cats, and exhaust. Then I went with a truck specific tune for the ECM.