What changed between 98 and 00 4.8's and 5.3's

[rally2]

I was just trying to find out what changes were made on the 98 engines to the 00 year. What changed to up the rated horsepower numbers. Can a 98 be updated with what changed or would it be better to go aftermarket?

[farmtruc]

the 98's definitely came with the older TBI Vortec engines. however some of the 99's came with the that or the new ls1 style engine. So were you wanting to compare the older TBI engines to the new 2000 engines, if you specify some of the cubes or what liters i can answer your question. Some of the limited and z71 tahoes in 2000 came with the TBI engine too.


later,

allen

[SSilverado60]

the 98s werent TBI. They were MPFI, all the vortec motors are MPFI. they started that in 96.

the 96-98 vortec motor is based on the old gen II design, basically the same as the gen I with a few changes. It has the vortec heads that are poplular to swap onto the older engines because they flow very well.

The new vortec motors, the 4.8/5.3/6.0, in a nutshell are cast iron versions of the LS1 motors that are in corvettes and camaros. they have a redesigned block that is similar to the original small block chevy but with lots of changes. The heads are completely different, so is the firing order, and they are all 6 bolt mains instead of 4. there are a lot of other changes as well but those are probably the biggest.

Your 98 motor has potential, but it doesnt have the aftermarket support like the new motors have, i think the hardest thing with the older motors is that its hard to find a place to tune them. nobody that i know of does custom tunes for them.

you cant update your motor to have the things that the new motors have, but your motor does have potential. but you cant go wrong with an LS1 or 6.0 swap

[farmtruc]

Originally posted by SSilverado60@Sep 9 2003, 03:07 AM
the 98s werent TBI. They were MPFI, all the vortec motors are MPFI. they started that in 96.

MPFI, are we on the same level? multiport = no FI = yes,

my 99 tahoe has a TB sitting ontop of the intake, and it's a 99, that is not considered MPFI
here:
"‘Mpfi’ stands for 'multi point (electronic) fuel injection'. This system injects fuel into individual cylinders, based on commands from the ‘on board engine management system computer’ – popularly known as the Engine Control Unit/ECU."


My TB is a batch fire system with only 2 fuel injectors and so are all the engines made before mine, Vortec that is.
The SPFI system started on the 99 Silverado's, they have 8 injectors, one for each cylinder.
However, tahoes didn't start that FI system until '00, even then, some tahoe still had the older TBI unit, up to 2001.

It gets confusing becuase GM mixed these together and had an overlap with the TBI unit and the new LS1 style engine.

99 Silverados - present = MPFI (sequential)
whenever - 98 = TBI (batch)
some tahoes around 2000 had TBI also.

Like silverado said, your engine has some potential, it's just not ls1 based if it's a 98 (unless it's from a fbody or vette)
For upgrades, i'd think some headers, catback, 1.6 rollers, and a tune would wake it up.

If you are asking about what changed and your referring to the TBI style engines, well not much changed, and no need to bring it up to the 2000 level. If you are talking about your 98 compared to a 2000 silverado 5.3L, then you're gonna have to mod it pretty well, but it's very possible to surpass it. Heads/cam and the other mods and you should easily be there.

good luck, and sorry for the confusion,

allen

[rally2]

Sorry my bad I meant 99 to 00. I have a 99 4.8 and saw that the rated output is like 15 HP and I don't remember how much torque on the newer 4.8's. I was just curious if they changed something mechanical or if it was just a new map in the PCM.

Sorry for the confusion.

[farmtruc]

oh now you tell us, hahahaha, that makes a huge difference, telling us what engine you have.

the tuning is a tad different and there was a tad change on the cam

went from a 115deg lobe separation, toa 114. and the from 118/112 for the early 99's to 112/116


got that info from my chevy ls1 peformance book, it's a nice reference


allen

[rally2]

Cool thanks,

Now I know I can make a few changes and get basically the same output as a newer 4.8. I figure a remap, new exhaust and filter should get me going in the right direction.

[SSilverado60]

our 98 suburban didnt have TBI, it was MPFI. It had the 8 injectors and the throttle body bolted on on the side of the motor. It was a big block so the intake looked different than the small block. The 96-98 vortec motors had a throttle body similar to old TBI units, but they were not TBI, they have 8 injectors at the end of the intake manifold.

[Big Bodie]

My friend has a 99 Silverado with what I beleive is called a 'CPI' Central Port Injection. There is a TB with out injectors (which is towards the front of the engine) and the fuel goes into the center on the manifold, the manifold is almost flat shaped. I found a pic one time and it sure looks strange, but works ok.

[farmtruc]

wow, all kinds of configurations coming up , what the hell did gm do ,