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350 vs 383 vs 400 vs ls 6.2

mudbuggy

mudbuggy

1/2 ton status
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Jun 10, 2010
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Indianapolis, Indiana
I am assuming that I am not the only one with this question banging around in my skull. I have been deep in thought about motor swaps for my suburban. It is an 89 with the factory 350, 700r4, transfer case (I forget) and 10 bolts front and rear. Over the course of time I have aquired a lot of spare parts for the 350, but I keep leaning toward a 6.2 replacement. I keep coming back to the original 3 when I think of all of the accessories that I would have to junk instead of getting use out of the spare parts. It leads me to wonder what accessories that fit my motor now would fit a 400 block if I would go that way. The prices for all of the ls components are crazy, and I am not going to spend 20k on a chromed out motor, just more crap to keep clean.

I sat down and went through the parts catalogs and talked to a few engine builders and I came to this conclusion, I would spend an additional $5000 to build a ls 6.2 compared to a with the same horsepower and torque. I don't see spending that additional money just to gain 5-6 mpg especially when my daily drive is 20 miles one way, right now I can fill my tank and run back and forth to work for 2 weeks. Granted it would be great to bring my truck into the next generation of computers, and all of that but I still have issues with the money.


I know that the rest of the powertrain will need to be upgraded. I am in the process of doing the 14 bolt now and I am collecting parts for the 700r4. I am also thinking about building a 14 bolt front axle, just to say I did it, but it would probably be the last part of the powertrain done including after I install the powerplant. I have not decided what I will do for a transfer case ( doubler, or what) and I'm not really worried about it right now. I am leaning toward a doubler, just for **** and giggles!


So how much of the stuff that is on my motor now would bolt up to a factory 400? Thanks guys
 
damn near everything
there are only slight differences when it comes to balancing/flywheels/center bolt valve covers/angled center bolts for the heads/and steam holes for the heads.

what is the list of stuff you want to transplant?

PS> any smog requirements?
 
Nope no testing what so ever. Want to swap all of it, might even change to an a6 ac compressor if I can modify the ps bracket. Thought about keeping tbi, then remembered about the poor choices for cams. Might go with a carb. All options are open. During this time of the year I do the firewood haul (60 miles) one way once a week. No real long haul except the occasional long haul road trip. Thanks for your thoughts
 
Like K85 said, all the external accesories are a bolt on deal, but the balancer and flexplate are different.

How much power are you looking for? With only tuning and no internal mods I think they can squeeze a bit more power from the LS engines.
 
mudbuggy said:
Nope no testing what so ever. Want to swap all of it, might even change to an a6 ac compressor if I can modify the ps bracket. Thought about keeping tbi, then remembered about the poor choices for cams. Might go with a carb. All options are open. During this time of the year I do the firewood haul (60 miles) one way once a week. No real long haul except the occasional long haul road trip. Thanks for your thoughts
Click to expand...

60 miles is way to far for me to get wood.Try talking to tree services in your area lots of them just dump the wood they get and if there close by doing a job they'll even deliver the wood to you to save gas in there trucks.Works for me.
Keep the fire stoked!
0917111824a-2.jpg
 
I put a 406 in an old 90 GMC I had years ago. Was still TBI. Couldn't tell it was a 400 until you looked at the balancer, or took it for a ride!!! Truck would flat out haul A$$!!!!! But in order to use a bigger engine in a TBI you WILL need to get a custom chip programmed.

I've been reading up a little on LSX swaps, and wasn't overly impressed, in less you get the LS3 or L92 I think it was. They are over 400 horse/torque, but pricey to get. Then have the fun of doing with wiring. I'm gonna stick to my original plan, long rod 454 with a carb...
 
Id really like to know how a 6.2 LS is gonna cost you $5000 MORE than a SBC build? Thats insanity. To me it sounds like you have an engine builder scared of newer stuff.

Personally I would look into an iron block truck 6.0. You can get a under 100k running motor w/ harness and computer for under $1500 easily. And if memory serves me they are mid to high 300s on horse and 400 ftlbs of torque.

How much power are you looking for here? A 6.0 LS series could easily be brought up to 400hp and 450lbs with bolt ons and a tune. Thats alot of power.

Now on the SBC front. If you do decide you want to retain a SBC for the sake of parts availability you have then do not go with a 400 unless its a virgin block OR can be punched .010 over. There is also certain block numbers to look out for that are more prone to cracking.

Im not a 400 hater but they have to be done right and not over punched other wise all those tales of cracked blocks on the deck are true.

Everyone knows you cant go wrong with a 383 but you can also look into the 400ci kit they sell for 350 blocks. Again it would require the correct block numbers due to clearances but youd be ahead on the cracking issues.
 
If you're not worried about mileage and don't want a wiring nightmare...go big block. Especially in a burb. It'll be a wood haulin machine. Plus with everyone buying hybrids you should be able to find a good used motor with the whole truck still attached for a good price.

Sent from my DROID2 GLOBAL
 
I like my 408 sbc, its torqy. But after Zim gave me a ride in the Maiden yesterday.... Im highly dissapointed lol.:haha:
 
since the burb has everything set up for fuel injection, I'd keep that. If you don't want to deal with the TBI unit, look into aftermarket stuff like Holley or FAST EFI stuff. Just drop it in place of the stock stuff and you get a better EFI system. $$$ but at least you don't have to buy a TBI tank and sender like me :)
 
COCHEV said:
If you're not worried about mileage and don't want a wiring nightmare...go big block. Especially in a burb. It'll be a wood haulin machine. Plus with everyone buying hybrids you should be able to find a good used motor with the whole truck still attached for a good price.

Sent from my DROID2 GLOBAL
Click to expand...


I'm thinking the same. A good carbed 454 can be had for cheap if you look around. Easy to diagnos problems (if any), all you need is fuel and spark (one wire for power). Super simple, great hp and great torque. :bow:

Easy to work on, no need for fancy diagnostics. If your not good at rebuilding carbs, just have that done by a reputable shop. There are a few good Quadrajet rebuilders that have been discussed here on CK5. I bet with you do this swap for $1000. I picked up a complete nicely running 47,000 mile 454 with carb, all accessories, and TH400 for $600 last month. It was still in the truck and running, I had to pull it.

You can put an Oxygen sensor into your exhaust to help tune you carb perfectly. I think the setup runs for $150 from Summit racing.

I looked into the LS engine swaps (read some books, talked to a few fellows who did it) , but also felt they are expensive, and possible problems with electronics. Don't underestimate the torque of a carbed 454 for a work truck like you have in mind. I enjoy the shear simplicity, great power, and lower cost of these carbed BBC.

I think LS engines are great too :waytogo:....but they're not in my budget or experience base with the associated electronics. I would like a 6.0 if I ever did go that route.
 
numbers- I'd like to be in the 450hp range, ideally in a small block, and I have tbi now so if I stay fi I have the gear, its the torque that I'm looking for without loosing the mpg (unless I drop the hammer). That's my toss up, do I pay the money for the ls motor to be built and installed how I want it or do I go old school and keep the tbi and tweek the nipples til she screams, or do I go real old school and top it off with a carb and just adjust the fuel level twice a year. That's where I'm at.

zombie1969 -Thanks for the consideration of my fuel expenses and lack of wanting to deal with the local tree hackers. The truth be told I spend less to haul 4 cords of wood home from the cabin then I would spend to purchase and have them stack one rick (If the price for one rick is $50)!!!

FYI-

Firewood, hell now I wouldn't go that far for wood, unless of course it mine!!!

After the loggers cut 2% of the healthy trees, I asked them to give me a rough estimate of available firewood on the property including downed trees that they did not harvest (dead trees that were standing or down). He called me about a week and a half later and told me that I have anywhere between 15,000 -20,000 cord of wood. He said that he quit measuring the length, and diameters of the downed tops after the first week of counting firewood, he just made an educated guess about the tree he was looking at and added to the bulk amount.

1st picture - that's me next to my burban, that pile of SCRAP is one of FIVE on my property.

2nd picture - buddy running our splitter

3rd picture - snapped that half way up the main road, the two things at the bottom of the hill are my brother and his buddy before he went to Austrailia for college. That was taken from the maintenance vehicle that I have for down there.

How are the fuel guages (mpg) for a big block, compared to a small block carbed or tbi, and how does that compare to the ls mileage???
 
yea pics first two are from last weekend the last is from last year. I forgot to add the pics to the last post, I just got home from the cabin, unloaded the trucks and trailers, took a shower and took my wife to Red Lobster for dinner without the kids. Sorry, I'm a little tired!!!

2010-01-01 Brown County October 16 2011 008.JPG

2010-01-01 Brown County October 16 2011 009.JPG

proof of capacity.jpg
 
Sorry if those posts came off too cocky, wasn't trying to talk about firewood, just give an idea of the conditions for which I use my truck for. Sorry to the brotherhood!
 
Sounds to me like you've kinda made your mind up on not wanting to do an LS swap.

A 10:1 383 or 400ci w/ a small roller cam and vortec heads will easily yield you 450ftlbs. Look up "The Impersonator" engine build on google. It was a motor than one of the car mags built. 406 small block to replicate the nature of a 454 big block.

And just remember, the bigger the cam the more you're going to shift away from torque and move towards horsepower.
 
So with a smaller cam then chances are that I'd be able to stick with tbi?
Not decided yet still on the fence line haven't started leaning yet, lots of little bits and fragments still bouncing around my brain housing group. I am guessing that tbi will give better mileage compared to carb or is that a myth?

A built 383 compared to a 400 with the same 450 hp which would be less expensive (for the motor build)? I am thinking of getting a stage 2 or 3 from monster transmission 700R4, I don't know if that would make a difference on the motor, but then gain I would like to get a np 6500 too! Decisions, decisions
 
I think a big 383 would cost more to build to get the torque than a 400. My 408 is pretty torqy and i have standard heads and nothing fancy in it. I have no idea what the specs on mine are as far as power, not alot because its nothing too fancy.
 
Is there a difference in headers for a 4wd truck and a 2wd truck?? I hav a 5.7L in 89 K5 if that helps. Thanks
 
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