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Discussion Starter #1
Hey everyone. I have a 67 with a 350 crate motor with a 700R transmission and 3.73 gears. It's mainly for street use and I'm looking for more power with decent gas mileage (everyone's dream right?)

I was originally looking to put in or build a 383 stroker with a carb, but my mechanic has been pushing the idea of swapping in an LS1. I know it would take a lot of fabrication, installing a fuel system, and getting a new tranny.

I'd like to know from you guys with more experience than me, what are the differences between going a 383 stroker with fuel injection vs swapping in an LS1. Besides the all aluminum motor what should I expect to see in mpg, power, torque, reliability etc between the 2 motors.

Thanks!
 

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apples vs. oranges

old school vs. new school

two completely different paths to go down. Its all up to how you want to build your car

you reference "your mechanic" so it sounds like you are paying someone else to do all this?

If you've got plenty of money for this project, I'd say do the LS1 swap. Its seems like the hot fad these days. Just know it would likely cost a few-to-several thousands more than simply adding a stroker crank & pistons to your current engine.
 

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Discussion Starter #3
apples vs. oranges

old school vs. new school

two completely different paths to go down. Its all up to how you want to build your car

you reference "your mechanic" so it sounds like you are paying someone else to do all this?

If you've got plenty of money for this project, I'd say do the LS1 swap. Its seems like the hot fad these days. Just know it would likely cost a few-to-several thousands more than simply adding a stroker crank & pistons to your current engine.
I am indeed paying someone to help me do the work. I do realize the 2 paths are very different. I guess what I'm trying to find out is:

1) how do the 2 differ in terms of overall performance. High end? Low end? Throttle response?
2) I've read LS1's get around 18-22mpg, I know carbed 383 strokers get around 10-12mpg. Will EFI increase the stroker fuel efficiency at all to get closer to the LS1?

I know these cars aren't meant to be fuel efficient, I get that. But the initial increased cost for the LS1 swap may be worth it if the difference is 8-10 mpg over a lot of years of cruising and putting that pedal down.

If the cost is say 10k for an LS1 swap, and 8.5k for a stroker with fuel injection, then the LS1 is probably worth it in the long run?
 

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I think you have already answered your own question.

If you have the money to spend for the LS swap, do it. Even better, do a 6.0L

I can tell you that I have an LQ4 6.0L in my silverado. It is an awesome engine. I would love to have it in a musclecar. Excellent torque and throttle response. Crummy fuel economy, 10-12mpg, but the truck weighs 6000 lbs and has 4.11 gears. I also prefer iron vs. aluminum for durability purposes.

The LQ9 was the high output 6.0 truck engine.

Then there is the LS2 6.0 that went in the corvette and GTO starting in 2005. If you can afford this swap... do it! 400hp & 400 ft-lbs of torque... thats really all your need to know

The LS2 is the engine I seriously lust for



fuel economy? come-on... do you really care? If you actually do care, maybe consider a 5.3L vortec
 

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Both will put out about the same HP but the LS "may" get better MPG being more efficient.
You can keep you 700R4 using an adapter flex plate.
My buddy with an LS1 from a 98 Vette, Magnacharger, and a 6 speed manual (double OD) in a 87 Monte is knocking on the 30 MPG door, driving like an old lady on Sunday....but runs low 11's at the track.

I didn't build for MPG and have never measured it with the LS.
My total costs were in the $6-7K range, buying a rebuild-able motor, the re-build, LS3 heads (new), and the swap parts....complete. I also stayed with my carb and TH350.

IF you want it all (cake and eat it too) for ease of all the parts chasing and ETC., I like the erod kit.
 

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Discussion Starter #6
Both will put out about the same HP but the LS "may" get better MPG being more efficient.
You can keep you 700R4 using an adapter flex plate.
My buddy with an LS1 from a 98 Vette, Magnacharger, and a 6 speed manual (double OD) in a 87 Monte is knocking on the 30 MPG door, driving like an old lady on Sunday....but runs low 11's at the track.

I didn't build for MPG and have never measured it with the LS.
My total costs were in the $6-7K range, buying a rebuild-able motor, the re-build, LS3 heads (new), and the swap parts....complete. I also stayed with my carb and TH350.

IF you want it all (cake and eat it too) for ease of all the parts chasing and ETC., I like the erod kit.
So you are using a carb on your LS? How do you like it? That was another option someone suggested to me to keep the cost down. As I probably could afford a nice LS swap, I'd rather not spend it all as there are always other things to do as well. Such as rims, maybe a paint job etc. All in due time, but motor comes first now that my suspension is done.

Can you tell me more about this "erod kit" as I'm not familiar.
 

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Discussion Starter #7
Oh I see, it's the LS3 kit. Yeah, that looks nice, but it's pretty pricey too.

6-7k range, did you do the labor yourself?
 

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The biggest benefit that an ls motor has besides the better designed heads, is its ignition system. This is where the ls outperforms an old sbc. With a HEI Distributor setup, your locked in on your initial timing and your timing curve. With a distributor-less system you have the ability to change timing on the fly. Thats what the pcm is doing 1000's of times a second. It's getting data from the crank sensor and cam sensor to calculate where the crank is at a given moment and using the map sensor to know what load the engine is under it then references a table to decide what timing to use.

This is a basic explanation as lot more variables go into play, throttle position, knock sensor data, engine temp, and all but the basic is that.

With this a tuner can build a timing map that maximizes your car's cam and head setup and power adders, while getting the most fuel efficient timing during regular cruising speeds. The head design on an ls1 is superior and adds to help efficiency and high pressure 58psi fuel injectors allow for better air fuel atomization that adds efficiency...but it's the distributor-less system that lends itself to fuel economy the most.

I've built an 11.5:1 compression 408 Ls motor that puts down just north of 500hp N/A. With 3.42 gearing I'm getting 17mpg on highway and 13mpg in city. And running 10's at the track. The car itself is completely street able despite having almost 15 degrees of overlap on the cam (it rumbles). A radical cam like that in a sbc would be unwieldy on the street and get terrible gas mileage in comparison. It's the computer controlled timing that makes the difference.

That's my opinion anyways.
 

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What.is your knowledge level on tuning? A "tuner can come up with a base map and timing curve" Great. What is your comfort level in understanding that and being able to do that yourself someday instead of relying on somebody else? LS motors are cool, no doubt, but that 500 hp comes at a very high rpm that you won't be reaching on the street very often. The 383 will be making more torque down low where you want it and won't cost $6-7K to do it. Half of that will get the job done in all probability. What crate motor? Doe it have a roller cam? If it does, all you need is a stroker kit and some decent heads and you' re there. Need injection and get away from a "locked in" HEI? Put one of the self tuning fuel injection kits on it.
 

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The biggest benefit that an ls motor has besides the better designed heads, is its ignition system. This is where the ls outperforms an old sbc. With a HEI Distributor setup, your locked in on your initial timing and your timing curve. With a distributor-less system you have the ability to change timing on the fly. Thats what the pcm is doing 1000's of times a second. It's getting data from the crank sensor and cam sensor to calculate where the crank is at a given moment and using the map sensor to know what load the engine is under it then references a table to decide what timing to use.

This is a basic explanation as lot more variables go into play, throttle position, knock sensor data, engine temp, and all but the basic is that.

With this a tuner can build a timing map that maximizes your car's cam and head setup and power adders, while getting the most fuel efficient timing during regular cruising speeds. The head design on an ls1 is superior and adds to help efficiency and high pressure 58psi fuel injectors allow for better air fuel atomization that adds efficiency...but it's the distributor-less system that lends itself to fuel economy the most.

I've built an 11.5:1 compression 408 Ls motor that puts down just north of 500hp N/A. With 3.42 gearing I'm getting 17mpg on highway and 13mpg in city. And running 10's at the track. The car itself is completely street able despite having almost 15 degrees of overlap on the cam (it rumbles). A radical cam like that in a sbc would be unwieldy on the street and get terrible gas mileage in comparison. It's the computer controlled timing that makes the difference.

That's my opinion anyways.

Agree with Werewolf on this one...I've owned several Corvette's from the 327/340 hp / dual quad setup, super T-10 tranny and 4.10 gears @ 10mpg to the LS1 and LS2 venues @ 30mpg. The older carbed cars screamed bloody murder, but the LS cars would run circles around them. There is no comparison in performance, fuel economy, and reliability...period. :beers:
 

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What.is your knowledge level on tuning? A "tuner can come up with a base map and timing curve" Great. What is your comfort level in understanding that and being able to do that yourself someday instead of relying on somebody else? LS motors are cool, no doubt, but that 500 hp comes at a very high rpm that you won't be reaching on the street very often.

My level of understanding is I tuned the car my self. Logged and test drove it and came up with every parameter and every table myself. Many trips down the track, many hours of back road driving. You assume it only makes horsepower up high? That alone tells me your unfamiliar with what an ls can do or even understand what a power band really is.

If you don't want to take the time to learn how to tune a modern EFI engine (and I understand it's something the average car guy won't want to do), you can take it to any number of well known tuners or tuning outfits and have the car tuned. Unless your doing something radical or out there they won't need to spend more than a few hours with the car on a dyno to dial it in followed up with some street driving to dial in the daily driving parameters.
 

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Hey everyone. I have a 67 with a 350 crate motor with a 700R transmission and 3.73 gears. It's mainly for street use and I'm looking for more power with decent gas mileage (everyone's dream right?)

I was originally looking to put in or build a 383 stroker with a carb, but my mechanic has been pushing the idea of swapping in an LS1. I know it would take a lot of fabrication, installing a fuel system, and getting a new tranny.

I'd like to know from you guys with more experience than me, what are the differences between going a 383 stroker with fuel injection vs swapping in an LS1. Besides the all aluminum motor what should I expect to see in mpg, power, torque, reliability etc between the 2 motors.

Thanks!
I've actually done this experiment for you. My now-sold '68 Camaro had a Holley Commander 950 EFI system on it, 11:1 383, backed up by a T56 (0.5 to 1 6th gear) and 4.11s. Best mileage ever, babying it on a freeway on a long trip was right about 18 MPG. More normally it was in the 16.5 to 17 MPG range. An important part of the mileage issue is how well the engine pulls at your cruising RPM (really low end torque perhaps?). My 383 was never really happy running at about 1,600 RPM at 60 MPH. If I put my foot in it in 6th gear, my first reaction was then to immediately downshift to 5th. In order to improve my fuel economy, I think I would have had to gear it even lower to up the cruising RPM, or put in a milder cam to detune it.

My current '68 Camaro has a LS376/480 LS3 in it (376 cubic inches), same transmission, same rear gears and reliably gets 23 to 24 MPG on the freeway. Running along at about 1,600 RPM, it is extremely smooth, and pulls away cleaning (and pretty strongly) in 6th.

The 383 was about 365hp to the rear wheels, the LS3 is 440hp to the rear wheels. The Camaro with the LS3 is the closest I've come in a street car to the passing ability of a motorcycle - it simply flies around traffic on two lane roads - another pretty good indicator of torque. The 383 didn't like local 20 to 25 MPH speeds, the LS3 is smooth at all speeds.

In short, there is no comparison between the two, with the LS3 winning on power, economy and smoothness.

What.is your knowledge level on tuning? A "tuner can come up with a base map and timing curve" Great. What is your comfort level in understanding that and being able to do that yourself someday instead of relying on somebody else? LS motors are cool, no doubt, but that 500 hp comes at a very high rpm that you won't be reaching on the street very often. The 383 will be making more torque down low where you want it and won't cost $6-7K to do it. Half of that will get the job done in all probability. What crate motor? Doe it have a roller cam? If it does, all you need is a stroker kit and some decent heads and you' re there. Need injection and get away from a "locked in" HEI? Put one of the self tuning fuel injection kits on it.
Here's where extreme ignorance rears its head.

First, when any EFI engine is tuned by a competent tuner, that's pretty much all that's needed - the one tune - unless you change something. In an LS motor, the ECU does some additional learning, but that's all done around the base tune.

When you install a aftermarket EFI system on a 383, the first thing you need to think about is tuning. Do you want to and can you tune it? If not, is there a local tuner who knows the system you're using who can tune it?

There are excellent tuners for LS engines everywhere, because there are probably hundreds of thousands of these motors that have been hot-rodded and need tunes. Not so much for aftermarket EFI systems installed on SBCs. For example, I couldn't find anyone in the greater Los Angeles area who knew the Commander 950 system.

Don't get me wrong, I tuned the car myself and got it running well and making good power but remember that best ever 18 MPG? I think with a really good tune, that could have been a touch better.

Similarly, the self tuning systems will get the car running well and making good power, but stop there. For liability reasons the "self-tuning" systems are going to err on the rich side. Running rich is the enemy of fuel economy.

Moreover, any EFI system is going to require fuel system upgrades - one of the major costs of the LS conversions.

The OP has gotten replies from two types of posters - the first is those who have done it, the second is one who has read a little. I leave it to you to decide which advice is most likely closest to reality.
 

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You cand do you 383 for about $3500.

The LS will be at least double or triple that cost depending on what package you go with.

The LS will get you power, better mileage, reliability and won't leak.
 

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I recently put the Holley EFI TBI system on my 383 making 440 HP. The self-learning worked well and is mostly complete. I still have to do minor tuning on cold running and acceleration enrichment. Car is getting 19+ mpg with 0.68 overdrive and 3.73's. I used that Edelbrock EFI Fuel Sump kit so I would have an easy fuel system install and it appears to be working good so far...but we'll see how it handles the heat underhood this summer. I tried to talk myself into going the LS route like several friends, but I'm too old school.
 

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My level of understanding is I tuned the car my self. Logged and test drove it and came up with every parameter and every table myself. Many trips down the track, many hours of back road driving. You assume it only makes horsepower up high? That alone tells me your unfamiliar with what an ls can do or even understand what a power band really is.

If you don't want to take the time to learn how to tune a modern EFI engine (and I understand it's something the average car guy won't want to do), you can take it to any number of well known tuners or tuning outfits and have the car tuned. Unless your doing something radical or out there they won't need to spend more than a few hours with the car on a dyno to dial it in followed up with some street driving to dial in the daily driving parameters.
I know this might be shocking to you but I was addressing the OP. You've told me all I need to know about you in the KMJ thread. As far as taking the car to well known tuners you have to be able to schedule the time with them and the dyno. Smart guys will study and learn to do it themselves using a mega-squirt or EBL P4 Flash system (what I have).

OP, either engine will be good for what you want to do. They just take different routes to get there. Go with what you are most comfortable with and what you can afford. You can't go wrong.
 

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If I had an extra $5k+ to spend for all the good swap stuff (fuel,serpentine setup,headers,elec,extra bits, etc...),I most likely would have built an LS based engine, instead of the 421 I'm doing now.
Next time for sure.
 

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Re: Tuning.

I build my own LS motors and I understand the basics of tuning. The learning curve is fairly long and for me I prefer taking it to an expert for my tunes.

I have HP Tuners. I data log and send the file to one of the best tuners in the country. He adjusts the tune and emails it back. I flash the ECM and go. I repeat the data log and adjustments 3 or 4 times until I'm good

I don't paint my own cars either. Lol
 

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What exactly do YOU want, more power? better gas mileage(get a Prius or Cruze). These are 60's cars. The 350 engine that is in it is easily capable of 400 hp without abig investment. I just don't get why everyone expects 60's cars to be 2000's cars. It's like taking a rotary phone and gluing a smart phone to it. If you have an Ls and are happy then that's cool, it is all about personal preference. I love the new Ls but also love what these cars came with small or big block(ok especially big block).
 

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I have a 87 Trans am, was orig a 305 4bbl, I built a 383 with e-tec 170cc alum heads I used a late model roller block and a ZZ4 camshaft - it idles like a kitten, passed emission test and on hwy would get 14-16 (still carbed) and I ran it against my stock 99 Trans am LS1 6 speed car and the 383 pulled (barely) on T/A so there you go, extra cubes and can hang with a LS.
If I had to do again I would go with bigger heads and cam and its a bolt in is it worth the swap up? thats something up to you to decide, fuel system upgrade, exhaust, mounts, oil system, electrical upgrade-for fuel and ECM and tuning its NOT cheap but when your done if you trash an engine replacements are cheap to wild. You only have to do the conversion once
 
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