need help.. ASAP please all peeps..

[illgetit]

well i have a fun toy now.. its been a lot of work to get my truck the way it is now.. but the only problem is that when i take it on the hwy it looses all power going up hill.. its hard to keep it over 50mph. i have been thinking its my old 200k pluss miles that i have on the motor or is it just because i have added larger tires.. i belive its the larger tires. i have been debating as far as cost and performance. as far as switching a ls? whatever x,1,or 2. but is it going to give me my road speed back and will it still work good as a 4x4?

please give me some feedback as far as what ls model is easyier to swap and do i have to switch out the intire drive train, (rear end, and tranny) i was told that the one i have now a automatic 4l60e is fine to work with a ls but the i was told that the rear is as well but then i have been told NO.,. whats the deal? i have been looking up lsx and other swaps but it seems to be for lowered trucks and i am lifted so all info would be great...

thanks guys and gals..

Much love for the Chevy..

[GeorgesBlazah]

[illgetit]

ok so your saying you have

7.25 Front diff housings:
1. Standared aluminum casting
2. Cast iron casting

Rear ends:
1. 7.5" ring gear 26 spline from 83 to 92
2. 7.625" ring gear gear 28 spline from 88+
3. 8.5" ring gear 30 spline from 95+, standard for 98+ ZR2's with rear disks

Axle ratios and their RPO Codes:
The 2wd, 4wd S10 and full size trucks use the same codes.
If it has a factory posi it will have a G80 code.
The other G codes are GU2=2.73, GU4=3.08, GU6=3.42, GT4=3.73 and GT5=4.10.
Look in the glove box for the RPO code sticker.

Transfer case versions:
1. 231 mechanical lever
2. 231c HD mechanical lever with wider chains
3. 233 electronic transfer case, note, not all have wide chains but most do

NV3500 5 speed tranmissions:
1. Later versions 96+? had the 3.48 first gear and internal slave
2. Early versions had a lower 4.02 first gear and external slave

Auto Trans:
Who cares

Brakes:
1. Single piston 10" front brakes with rear drums are standard
2. Duel piston 11" front brakes, standard on 98+ Balzers and ZR2's
3. Rear disk, standard on 98+ ZR2's

on your rig what about the motor?

[96superflow]

Im willing to bet you didn't regear your axles when you lifted your blazer and added the larger tires. You more than likely have 3.42 gears, but thats just a guess. And i thought i read somewhere that you have 33's on it. When i was still IFS i put a 2" bodylift on mine and added 31's and it was pretty sluggish off the line but it kept rolling on the hwy. with 3.42s. if you are running 33's you should regear them to at a min 4.10s and i would even go with 4.56s or 4.88 if you take it off road any. The engine isn't really a big problem, its really all in how you gear it.

[illgetit]

no i didnt. i have 3.73 on rear and front. its a automatic.. i was told that if i go to the 4's i will have a really slow start and eventualy get up to speed. so 4.10's would you think give me back my top end speed and still have the tork for off roading.. i was wondering if the ls is only for drag and racing vs off road. ive been told by lots of peeps that the 4.3 is fine. so maybe running 4.10's and a new 4.3Vrtech should be fine. only a new 4.3 cuz mine has over 200k and might be going...

[96superflow]

I would regear to 4.56 at a min. I have had a ton of 4.3 ltrs and the only time i needed to replace them was 1. spun a main bearing(but it still ran for probably 200 miles) and 2 because i hydro locked the motor and bent 2 connecting rods. 3.73 gears are too numerically low for imo for 33s. 4.56s or 4.88s would allow your engine and transmission to work easier to and get it in the right rpm for that size of tires. This is a good indicator of what you want gear wise for the size of tires you are running.
http://www.4wheelparts.com/aux_incl/gear_ratio.html

If you read off of it, 3.73 are the min. for that size of tires. I personally would rather be right up by the gray to yellow area.