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Ls swap questions

6070 Views 18 Replies 10 Participants Last post by  Von Rottes
I will be using this post for just questions. I got a 2001 4.8l I'm throwing in a 2003 bagged single cab 2.2 Sonoma. On the exhaust does 2.5 "from headers to 3" sound good? Looking at using the stock Silverado cats with a quiet thrush single in to single out muffler with a side exit exhaust before rear tire. Second question on the transmission, what is the best transmission/torque converter to run? I will be getting truck tuned. I have access to a 2003 suburban tranny and 1998 s10 tranny. I have also read the s10 torque converter is better to run. I'm not rebuilding the motor (200k+) going to run it till it blows, then upgrade to 5.3/7 or rebuild. Has anyone rewired the stocks Silverado engine harness to work in a s10 or used stock harness/ fuse block in a s10. If so pm me. Would it be easier to use the Silverado engine harness, fuse block, cab harness, bcm? ( I have access to all the wiring from a 2001 Silverado.) I have been thinking about just pulling all wiring and using all the wiring from the Silverado. I will pull all tape and loom off and re route it. Cams. What is the best cam to run, stock, 5.3/5.7/6.0/6.2/after market? The steam valve, many people tap the water pump, anyone tap the radiator? Or have a better way? That's all for now.
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Most of your questions are already answered in various build threads, just have to search. as for the exhaust question 3 inch is too big for a 4,3, you will lose low end torque. Should be 2 1/4 into 2 1/2 for that size engine. Welcome to the group.
Whew. That's a lot of words and questions. @goes2fast gives the great suggestion of searching as many of those are basic questions.

Also try breaking out your questions and thoughts into different paragraphs to make it easier to read and understand the content. I honestly opened up a dozen other threads instead of answering this right away because of the run on nature of your post.

But I'll dive in and see what I can help anyway.

I got a 2001 4.8l. On the exhaust does 2.5 "from headers to 3" sound good?
With my stock 5.3 swap this is exactly what I ran for exhaust sizing. Seems to work well and sounds good with the stock sized magnaflow I put on.

Second question on the transmission, what is the best transmission/torque converter to run? I will be getting truck tuned. I have access to a 2003 suburban tranny and 1998 s10 tranny. I have also read the s10 torque converter is better to run.
2003 Suburban Transmission will bolt up directly to the 4.8 with the Suburban flexplate and nothing else. A 1998 4.3 S10 transmission will also bolt up to the 4.8, but will need a spacer on the flexplate.

Has anyone rewired the stocks Silverado engine harness to work in a s10 or used stock harness/ fuse block in a s10.
This has been done. Check out LT1swap.com for engine harness how tos, schematics, and pin outs. You can either do a stand alone or wire into the S10 fuse block. It's a bit like playing a memory game. Find the matching circuit on the S10 fuse block connector and connect the Silverado wire into it.

Would it be easier to use the Silverado engine harness, fuse block, cab harness, bcm?
Silverado engine harness is the best choice if you're doing the wiring yourself. Everything else is best from the S10. The engine harness merges quite well with the ~2000+ S10 because they were designed with very similar electrical and controls architecture. If the engine harness is done right you don't have to touch any other wiring.

I've completely rewired a couple trucks for reasons only known to the inner working of my head. While the results were exactly what I wanted it can be a time intensive process. I wholeheartedly support others in doing their own engine harness, but it can be a labor of love to go much deeper than that.

What is the best cam to run, stock, 5.3/5.7/6.0/6.2/after market? The steam valve, many people tap the water pump, anyone tap the radiator? Or have a better way? That's all for now.
Google "sloppy stage 2". It seems to work well with almost any style of LS build and is a very affordable option. With the right knowledge and probably dollars you can eek out some more for a certain style build, but hard to beat it's price and versatility.
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2.5's merged into 3" single is fine for 4.8, nice sound usually.

The sloppy stage II, whether you're referring to the Elgin E1840P, E1839P, or Jegs 200582 are all decent cams.

I run a cam not too different from those, a bit more lift and a bit more advance, but I can definitely vouch for being a fan of the 112 LSA.

The S10 torque converter is a bit doggish, depending on what you want. A TBSS V6 converter makes a good factory converter. I run a slightly smaller 11" Circle D 2600 stall converter, fairly happy with it, just had to fiddle with the shift and lockup tables for awhile to get it to behave where/how I wanted to. A sloppy stage II is going to work well with a converter that comes in around 2,000 to 2,400. Your desired rear gearing will affect that choice as well. The main point is to not bog the engine when you step on it and allow it to flash up to the bottom of its RPM torque range. Most LS engines don't make good torque below 2k, so the factory 1,600 to 1,800 stall speeds typically don't work well if you want a performance feel out of it.

On a budget though, for the trans changing the 1-2 servo, and putting in a shift kit is a better expenditure of money first.
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Wow, doesn't that cam call for a 10:5 minimum compression?
I'm running the 1839P cam in my 6.0. I would recommend using a stock or near stock cam with a 4.8 and a stock torque converter.
A 4.8 stock cam, stock torque converter, is going to be an old dog.

Honestly, you're adding about 60-80lbs nose weight, and a whopping 80 or so hp over the 4.3. You'd be better off to just hop the 4.3 up with a cam, you'd get most of the way to 4.8 power without the cost/hassle of the swap.

In terms of the learning experience, swaps are a lot of fun. In terms of performance improvement expect to be disappointed when you're finished.
In terms of the learning experience, swaps are a lot of fun. In terms of performance improvement expect to be disappointed when you're finished.
Dang. That's not what I wanted to hear.
Dang. That's not what I wanted to hear.
Engines produce power according to air & fuel provided, and the volumetric/thermal efficiencies they operate at. However they're just air pumps. Ultimately you've got a pump displacing 4.3 L of volume per cycle, versus one displacing 4.8 L. So you're adding 0.5 of a L of total displacement. The VE/TE of the LS platform is better than the SBC for a bunch of small reasons.

Hold out and shop around for a 5.3L you'll be happier for the time/money invested. With a 5.3 you go from 0.5L more displacement, to 1.0L more, double your gain, for the same functional cost of the swap, plus you're up over 300 ponies, which is somewhat the magic number for street vehicles.
Oh ok. I thought you were talking swaps in general, not just the 4.8. I really like the 6.2 but so far it looks probably a 6.0 for me.
Any LS 5.3 and up is great in an S10 :) With a decent wake-up cam. Stock cams in all the truck motors suck and leave a lot to be desired.
Ya that was a night of drinking.
Any LS 5.3 and up is great in an S10 :) With a decent wake-up cam. Stock cams in all the truck motors suck and leave a lot to be desired.
Above you stated that a TBSS converter was an improvement over an S10. Can you elaborate a little, it might be worth me rounding one up. Will the converter have an ID stamped on it?
you sure it was a TBSS,and not just a plain ole 4.2 TB
Yeah sorry, that'd be just a TB V6 converter. Not sure if the SS even came with a V6 or if it was a LS2 6.0 by default. Anyway yeah, the standard trailblazer converter.
I did a search but couldn't find any reliable evidence given the stall speed over a stock 4L60E 4.3 converter.
4.2 is an L6




all TBSS were V-8s
didnt the TB converter have a different flex plate to converter bolt pattern difference than the 4.3?
the trailblazer had a inline 6 cyl (no V6), or the 5.3

the tbss had a 6.0
I will be using this post for just questions. I got a 2001 4.8l I'm throwing in a 2003 bagged single cab 2.2 Sonoma. On the exhaust does 2.5 "from headers to 3" sound good? Looking at using the stock Silverado cats with a quiet thrush single in to single out muffler with a side exit exhaust before rear tire.
I'm running All 3" on my 5.3.. Custom 3" y-pipe from the headers to a merge and single 3" all the way to the rear, behind the spring.


Second question on the transmission, what is the best transmission/torque converter to run? I will be getting truck tuned. I have access to a 2003 suburban tranny and 1998 s10 tranny. I have also read the s10 torque converter is better to run. I'm not rebuilding the motor (200k+) going to run it till it blows, then upgrade to 5.3/7 or rebuild.
Ehhhh go with the Suburban transmission... the S10 is supposedly weaker...something about smaller diameter parts I dunno.... but I do know any transmission that isn't behind a LS engine will require a spacer for the TC

Has anyone rewired the stocks Silverado engine harness to work in a s10 or used stock harness/ fuse block in a s10. If so pm me. Would it be easier to use the Silverado engine harness, fuse block, cab harness, bcm? ( I have access to all the wiring from a 2001 Silverado.) I have been thinking about just pulling all wiring and using all the wiring from the Silverado. I will pull all tape and loom off and re route it.
I did.. Originally I used the Silverado Fuse block, then switched the a 6 fuse block and now I have it all run into the original fuse block in the truck...for a '03 I THINK you can just repin the C2 connector and plug it into the factory block in the S10.

The steam valve, many people tap the water pump, anyone tap the radiator? Or have a better way?
I'm using an adapter from JTR that has an air bleed and Nipple for the steam vent. splices inline with the top radiator hose.
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