LS vs 383

[stepside68longbed]

I'm debating which one to do 383 or LS I will be driveing my truck every day so I'd like to get decent gas mileage. I will only be running a fan and alt no ac or other bull crap just an FYI there.

LS 327ci 327hp
LS people I have a few questions.

What is the difference between the numbers like ls1,2,3 so forth?

Will it bolt up to my 350turbo automatic trans? (I may buy a new trans... What should I look at?)

Will I need to change my gear ratio?( I'm buying a 5 lug axel off a guy thinking about makein it posi)

How would my mpg be not playing with it? I will drive my truck not let it sit just for me to look at..

Should I get new harnes to be reworked? (Or do they put all new wires on?)
Where do I take them to do so?
How much does that cost?

383 310hp 385TQ

What would my mpg be driveing it no playing?

Wouldn't my wireing harness hook up the same?

[bpatrol]

search is your friend, most of these have been answered time and time again. If mileage is your first priority the ls will make more power efficiently cube to cube.
I would think the 383 depending on build will be slightly stronger then a 5.3(325ci)
but it will not be much.
An LS will bolt up with an inexpensive adapter to any gm trans. but once again if mileage is your goal an overdrive trans is a must.

Good luck and do some research on here there is lots of info with just the questions you asked.
cheers
bpatrol

[imjeff]

I have been running big blocks for a long time, but I'm about 90% sure I will put an LS in my K10 when the 396 pukes or I get the time. The 5.3 in our Tahoe is great.

[Lou Boffa]

interested

[DaddyO]

Speaking as a person who has done the LS conversion I would first do a cost comparison on the two engine set ups. Doing research is the key here. I chose the LS1 for my build for the reliability of it.

A brief description of the LS motors can be read here but it is not all inclusive:

http://www.ssrfanatic.com/forum/f5/d...nations-27127/

If you are looking for better mileage I would opt for a newer transmission ( like a 4L60E).

Youj dont necessarily need to change the gear ratio. I'm running a 3:73 gear in mine with a 5 lug setup.


Gas mileage wise I get about 22 mpg.

With a LS engine I would recommend getting a new harness. Doing so will elimenate a lot of clutter not to mention time and frustration due to the fact you don't know the history (wire breaks, etc.). Several shops sell new harness online and pricing varies.



Here is my set up:




Good luck!!

[brad_man_72]

Gm doesn't make a 327cid ls based engine. The 5.3L is the closest at around 325 cid.
All ls engines have an aluminum block and are quite pricey when compared to the Ls based truck engines that all have iron blocks.

All ls based engines will bolt to any transmission as any other sbc or bbc.
The cost of bulding a comparable hp sbc is about the same if not more than swapping a junkyard truck engine. Then if you want more power the sbc will possibly need to be rebuilt for n20 or forced induction while the ls based engine might need bigger injectors, fuel pump, and a tune.

[stepside68longbed]

it must be a typo then I have a picture right here Chevrolet performance #809-19244096 LS 327ci Engine 327hp 347TQ.

I will build later as for right now im getting a crate. I've price checked 3,600 for 383 and 4,200 for the LS.

that does look pretty sweet

383 cast iron block 310hp 385TQ.. so far the stroker seems better and more TQ and I could use spray later on I will get an ls in another project I plan on having a few

I looked up that 4L60E on monster transmition and that aint bad for a new better trans 1,430 so ill end up getting that to go with the 383

[leftybass209]

There really shouldn't be too much of a debate if gas mileage is a question. What will hurt mileage is the 3 speed auto. A 4 speed auto would keep rpms low. The ls1 can be built to push f - bodies into low 10 second quarters so there's no doubt it can be built plenty powerful enough. It just has refined head design and fuel injection to bump mpg's. Either motor would be cool.

[fast&low]

Not a typo that is a LS327 5.3

[72MARIO]

Originally Posted by imjeff

I have been running big blocks for a long time, but I'm about 90% sure I will put an LS in my K10 when the 396 pukes or I get the time. The 5.3 in our Tahoe is great.

I have only ever owned carbed and tbi engines. Just bought a 2005 Tahoe with a 5.3. I love it I would be great to have that engine over the 383 I had in my work truck any day.

[bpatrol]

the ls327 designation is just marketing people know 327's so they market them as such. Its no big deal and not worth debating. the reality is its a 325 close enough for me.
ls based engines are aluminum and iron. Iron being less expensive without a real drop in performance once you change certain parts.

One Big benefit to ls based engines is they run wayyyy cooler temp wise
If you are worried about all the wires just carb it. very simple almost the same as wiring a sbc. and still good mileage and power depending on carb. (600 electric choke) would be great.
good luck

[Andy4639]

Hands down LS motor.
A stock 6.0 LQ4 is rated 325 HP at the fly wheel stock!

A lsx LQ9 is rated at 345HP at the fly wheel stock!

Plus you will get 16-20 MPG with the 4l80e are 4l60 are if you go big get the new 6 speed auto and get even better MPG.

No 383 is going to get close to the numbers of the LS engines and the money is doubled on the 383 to get the HP out of it.

I just finished my 6.0 LQ4 swap with 4l80e and it's dyno'd at 280 HP at the rear wheels not the crank. 305 Torque at the rear wheels. It's all stock except for the long tube headers. + it's getting 17MPG.

[boostedc10]

Originally Posted by bpatrol

the ls327 designation is just marketing people know 327's so they market them as such. Its no big deal and not worth debating. the reality is its a 325 close enough for me.
ls based engines are aluminum and iron. Iron being less expensive without a real drop in performance once you change certain parts.

One Big benefit to ls based engines is they run wayyyy cooler temp wise
If you are worried about all the wires just carb it. very simple almost the same as wiring a sbc. and still good mileage and power depending on carb. (600 electric choke) would be great.
good luck

This post isnt attacking you bpatrol but I never understood why anyone would carb an LS engine, yet people do it all the time. Nothing like throwing money out the window to loose HP/Torque not to mention fuel mileage.

[bpatrol]

its okay I don't take it as an attack on me, we all arel here to learn
Fact is a carbed ls will make more peak hp and tq then a fi engine. fi is better everywhere else.
if you put a proper size carb with vacuum secondaries and an electric choke with a dual plane intake they get great gas mileage.
I have a 67 Camaro that has a 6.0 carbed ls motor with a quick fuel carb and gets 25 mpg with a 6 speed and 3.73 rear end my friend has the same set up but f.i. and gets about the same and both cars are 440 plus at the wheels.
These motors just breathe better and make power easier, carbed or fuel injection.

Lastly some people still want the cool look of a carbed motor. with a msd box firing the coils everything else is exactly like a small block so much easier to wire and no computer needed.
Sometimes people are just starting out with a block and need to buy everything

god speed and good luck

[fast&low]

Fuel mileage yes but where do you get that you loose hp/torque?

[boostedc10]

Originally Posted by fast&low

Fuel mileage yes but where do you get that you loose hp/torque?

Obviously this is not always the case and depends on the carb and intake you choose, no different than the throttle body and intake you choose on the EFI system.

All I am saying is other than for price (if starting with a base engine, and still not a big cost different with the amount of parts floating around the junkyards), the fear of electronics or the looking "old school" I guarantee dollar for dollar i can go faster with EFI.

The only advantage a carb has over multiport fuel injection is the atomization of gas due to its pressure differential.

If we are talking prostock motors I agree with bpatrol that a carb motor makes more peak power, but we're not. The cylinder to cylinder fuel distribution of efi blows a carb out of the water. Not to mention I can make on the fly adjustments with a laptop

Remember in the end it is about combustion efficiency!

[Matt Cramer]

Originally Posted by stepside68longbed

I'm debating which one to do 383 or LS I will be driveing my truck every day so I'd like to get decent gas mileage. I will only be running a fan and alt no ac or other bull crap just an FYI there.

LS 327ci 327hp
LS people I have a few questions.

What is the difference between the numbers like ls1,2,3 so forth?

They're RPO codes, and not all of the "LS" motors actually have RPO codes that start with LS. I see DaddyO posted a link to a pretty good list.

Will it bolt up to my 350turbo automatic trans? (I may buy a new trans... What should I look at?)

Yes, but chances are you will either need to buy a new flexplate or modify yours with a Dremel, depending on what flexplate you find on the engine and what converter you have. You'll want to check both. I'm using a TH350 bolted to an LR4 (the iron 4.8... I got one cheap.) The 4.8 had been backed by a 4L80E, and I'd seen a lot of writeups on the Internet saying, "Sure you can make that flexplate work; just elongate the holes so they'll fit a TH350 converter's 11.5" bolt pattern!" Well, guess what? My converter had a 10.75" bolt pattern; that didn't work too well. Had to buy a different flexplate from Advance Adapters.

If you're thinking transmission swap, you can use the 4L60E or 4L80E that came with the engine, and you'll get an extra gear that will help with mileage.

Will I need to change my gear ratio?( I'm buying a 5 lug axel off a guy thinking about makein it posi)

Not really, although LS motors often rev a bit higher.

How would my mpg be not playing with it? I will drive my truck not let it sit just for me to look at..

Something went wrong with my speedo drive when I did the swap that I'm still trying to straighten out, but it seems to be getting somewhat better mileage than the 350. The 350 wasn't very well tuned, though.

Should I get new harnes to be reworked? (Or do they put all new wires on?)

Depends on whether you're using a stock ECU or aftermarket controller and how wiring-averse you are. Stock harnesses are a bit of hassle to rework, but if you're able to put together good safe wiring splices and have the time, go for it. If the guy who previously wired a Triumph Spitfire I used to have using lamp cord and wire nuts is thinking of doing the swap, he'd be wise to go with a ready to run harness.

[primetime]

how much is the 4.8/5.3 LS motors worth to get the motor, trans, and computer all together? you all have me interested now in the swap for my new '68

[boostedc10]

Depends on the trans. A 4.8/5.3l complete with trans in my area around 1000-1500.

[Lee H]

I'm on my 3rd 383. To get the rear wheel HP & Torque in a useable, streetable RPM band and the manners of an LS it cost about $6k (carb to pan) and you still need the transmission to handle that power, headers, etc. A complete LS pull out (engine, trans, all drive accessories, ecu, harness, etc) is about $2k. Another $2k for all the extras like mounts, headers, harness rework, tune, dyno, efans, upgraded fuel system, drive shaft, etc. and 20 MPG vs 10. It's not a hard choice to make. The first major failure of either the motor or trans and I'm making the switch to LS.

[Lees68GMC]

These 3 trucks all have Vortec 5.3s and the 4th (the Green one) is getting one soon. I'm prejudiced, we love 'em. If you know anyone with a Vortec or LSX V8 in one of our old 67-72 trucks ASK for a ride, you'll understand the Why part instantly.

It's funny to see the Carbed vs Fuel Injection discussions Again, really.

If carbs are Still so good why are there almost Zero Vehicles produced Worldwide with them. The Worlds Fastest dragsters, Bonneville cars would probably run Carbs on top of their blowers, instead of injecting.

I'll buy Nostalgia every time as a valid reason to Carb, but performance? I believe that ship has sailed and it ain't coming back.

[Lou Boffa]

Originally Posted by Lees68GMC

These 3 trucks all have Vortec 5.3s and the 4th (the Green one) is getting one soon. I'm prejudiced, we love 'em. If you know anyone with a Vortec or LSX V8 in one of our old 67-72 trucks ASK for a ride, you'll understand the Why part instantly.

It's funny to see the Carbed vs Fuel Injection discussions Again, really.

If carbs are Still so good why are there almost Zero Vehicles produced Worldwide with them. The Worlds Fastest dragsters, Bonneville cars would probably run Carbs on top of their blowers, instead of injecting.

I'll buy Nostalgia every time as a valid reason to Carb, but performance? I believe that ship has sailed and it ain't coming back.

For me the solution to all these quandaries: FI vs carb, stock vs lowered, short vs long, patina vs paint, stepper vs fleetside is always the same...I gotta get one of each! That is a fine line-up.

[trkfrk]

Nice trucks�� I really like the orange and white one..

[Matt Cramer]

Originally Posted by primetime

how much is the 4.8/5.3 LS motors worth to get the motor, trans, and computer all together? you all have me interested now in the swap for my new '68

I paid $460 for a complete 4.8 with harness but no ECU or transmission. That included all accessories including the A/C compressor.

[First c10]

I picked up a 2011 LC9 all aluminum / 6L80 trans with all drive accessories ecm pedal harness trans lines oil cooler lines shipped for under 3K. the short block I was going to build was almost $2K in partsd and I was going to have to rebuild myself. Of course there is all the other cost and learning curve..... but what I have seen so far in my build I am going to be happy happy happy!!!