383 vs 408
Thread Starter
Launching!
Joined: Apr 2008
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383 vs 408 Long story short, I just finished rebuilding the top end of my high miles LS1. Started it, and the tick I had attempted to get rid of....was still there. I'm going to have a shop give me their opinion tomorrow, but my guess is it's something in the bottom end (piston slap, rod, something).
I'm trying to stay positive here b/c I did ALL of the top end rebuild myself using a LSX book. Never did any of this stuff before. I am proud that it even started and sounds pretty damn awesome (tick aside). That being said, if they quote me anything near $1000 to fix this thing, I'm just going to say screw it time for a new short block.
Here is my question... How much power can a 383 stroker make with ported heads, aggressive cam, and a good intake like FAST? Car is a 6 spd btw with 3.42's. I'm going to do some searching on here but figured I'd ask b/c I kinda need to know if its worth it. I'd really like to make 500rwhp+ n/a.
I'm trying to stay positive here b/c I did ALL of the top end rebuild myself using a LSX book. Never did any of this stuff before. I am proud that it even started and sounds pretty damn awesome (tick aside). That being said, if they quote me anything near $1000 to fix this thing, I'm just going to say screw it time for a new short block.
Here is my question... How much power can a 383 stroker make with ported heads, aggressive cam, and a good intake like FAST? Car is a 6 spd btw with 3.42's. I'm going to do some searching on here but figured I'd ask b/c I kinda need to know if its worth it. I'd really like to make 500rwhp+ n/a.
Staging Lane
Joined: Jun 2014
Posts: 67
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From: Alabama
Most here would say go ahead to the bigger motor if the motor you have now is shot.(assuming you have the funds for the 408) Also the 408 will open up for more heads options for you compared to the ls1 motor. Finally, 500+ wrhp seems to be just a tad bit out of reach for the ls1, for most people, including stroking out to the 383. Some have gotten it or very close, but not usually obtainable. Most top out between 470-485hp. The 408 with the right combo should get you there.
I think your 500RWHP goal is attainable for a 383 with all those goodies if you don't skimp on the heads; you could probably hit that with even with stock ported 243s from certain porters with the right cam 
You also need to consider the cost of a new quality aftermarket clutch and new rear end as well for that sort of HP.
You also need to consider the cost of a new quality aftermarket clutch and new rear end as well for that sort of HP. I've weighed the same dilemma for months now. A 383 can reach 500 but will be pretty radical. I'm doing a 408 and with a decent combo, should reach between 500-525 rwhp pretty easily.
Last edited by ragtopz28; Oct 5, 2015 at 04:34 PM.
A well done 346 should be a handful to hook on the street on street tires at legal speeds.
If you need a crank a 383 becomes a reasonable consideration. Far as the 408 are you going to like how the car handles with another 100lbs on the nose?
Yes a 408 opens up head options and allows for more cam duration within a rpm range allowing more potential HP but comes with a weight penalty and unless on slicks with a rollbar on the track is probably completely unusable potential.................................
If you need a crank a 383 becomes a reasonable consideration. Far as the 408 are you going to like how the car handles with another 100lbs on the nose?
Yes a 408 opens up head options and allows for more cam duration within a rpm range allowing more potential HP but comes with a weight penalty and unless on slicks with a rollbar on the track is probably completely unusable potential.................................
I weighed the pros/cons thing last year and decided to have a machine shop do all the prep work on my LS1 and get it ready to bolt up. Then I assembled it out in the garage. If you did the top doing the bottom is just as easy or maybe even easier. It is incredible to worked standing up with it on a stand. Oh that makes i so easy. 
I didn't want the extra weight of iron in the nose of my GTO. I like the way it handles now. A LS2 aluminum block would also add more cost out of an already empty wallet. The upgrade was rotating assembly, new cam, all bearings, oil pump, little stuff and a clutch so it still was pricey. I already had a NW 102, FAST 102, injectors and 243 heads. I finished it last Oct and put it away but drove it this summer.
The torque of a stroker on the street blows off any tires I can fit on my GTO already. A year has gone by and I decided to finish it off by switching the 243 heads and get Mamo 220s with hollow valves, Ti retainers, etc and the car should get even edgier. It is not built to be the fastest car or the biggest dyno queen, just a fun car and it's doing that even now. I should end up 475-500 through 3.91s.
I didn't want the extra weight of iron in the nose of my GTO. I like the way it handles now. A LS2 aluminum block would also add more cost out of an already empty wallet. The upgrade was rotating assembly, new cam, all bearings, oil pump, little stuff and a clutch so it still was pricey. I already had a NW 102, FAST 102, injectors and 243 heads. I finished it last Oct and put it away but drove it this summer.
The torque of a stroker on the street blows off any tires I can fit on my GTO already. A year has gone by and I decided to finish it off by switching the 243 heads and get Mamo 220s with hollow valves, Ti retainers, etc and the car should get even edgier. It is not built to be the fastest car or the biggest dyno queen, just a fun car and it's doing that even now. I should end up 475-500 through 3.91s.
Last edited by svede1212; Oct 8, 2015 at 10:02 AM.
I got an iron block in my car; didn't notice the extra weight at all. Unless you Autocross the car, I'm not so sure you would even notice either.
With that said, either option would work. I would go with the 408, or a stock stroke 370 even. The larger bore allows you to run LS3 style heads if you one day get the itch. You could probably even sell the LS1 shortblock to offset the cost of the new engine.
With that said, either option would work. I would go with the 408, or a stock stroke 370 even. The larger bore allows you to run LS3 style heads if you one day get the itch. You could probably even sell the LS1 shortblock to offset the cost of the new engine.
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TECH Fanatic
Joined: Jul 2007
Posts: 1,802
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From: Wilmington, De
Once you look past achieving the magical 500 number and start concentrating on having a car that drives well with plenty of low-end and midrange grunt, I think you'll be happy with either choice. Personally, I would go for the bigger bore, but there isn't anything wrong with a 383. Plenty of power can be made with both.
TECH Junkie
Joined: Dec 2012
Posts: 3,614
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From: Iowa
I'd look into more bore and less stroke. You can have great throttle response and still more cubes than stock. If it were me, i'd look into going 4.00 bore with stock stroke (if the sleeves have enough meat). When you shove a 4" stroke into a stock block, the skirts start to come out the bottom of the sleeves. You can make it work but longevity starts to become an issue and it will eventually start to eat oil. There are plenty of people here that have done 383 and 408 and had great success don't get me wrong, but I think a 6.0 would be something to at least consider.
TECH Addict
Joined: Aug 2005
Posts: 2,305
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From: Monroe,NY
Long story short, I just finished rebuilding the top end of my high miles LS1. Started it, and the tick I had attempted to get rid of....was still there. I'm going to have a shop give me their opinion tomorrow, but my guess is it's something in the bottom end (piston slap, rod, something).
I'm trying to stay positive here b/c I did ALL of the top end rebuild myself using a LSX book. Never did any of this stuff before. I am proud that it even started and sounds pretty damn awesome (tick aside). That being said, if they quote me anything near $1000 to fix this thing, I'm just going to say screw it time for a new short block.
Here is my question... How much power can a 383 stroker make with ported heads, aggressive cam, and a good intake like FAST? Car is a 6 spd btw with 3.42's. I'm going to do some searching on here but figured I'd ask b/c I kinda need to know if its worth it. I'd really like to make 500rwhp+ n/a.
I'm trying to stay positive here b/c I did ALL of the top end rebuild myself using a LSX book. Never did any of this stuff before. I am proud that it even started and sounds pretty damn awesome (tick aside). That being said, if they quote me anything near $1000 to fix this thing, I'm just going to say screw it time for a new short block.
Here is my question... How much power can a 383 stroker make with ported heads, aggressive cam, and a good intake like FAST? Car is a 6 spd btw with 3.42's. I'm going to do some searching on here but figured I'd ask b/c I kinda need to know if its worth it. I'd really like to make 500rwhp+ n/a.
Thread Starter
Launching!
Joined: Apr 2008
Posts: 289
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Are you sure the tick isn't an exhaust leak? I had a friend who just did heads and lifters on his 5.3. Once he had it running there was a tick that sounded like a lifter tick. We searched and listened with a stethoscope and couldn't find the tick. Pulling his plugs I seen a lite tint of soot on 2 of the plugs. Found that the header gasket was leaking underneath. He installed gasket upside down. The tick never sounded like it was coming from the exhaust. Now he is tick free.
Update: I just purchased a LQ4 which I'm hopefully picking up next week. Going to drop it off at the machine shop and have the short block rebuild started. Once that's done I'm going to swap parts off the LS1 onto the LQ4 and hopefully have a brand new stout 408 to put into the camaro. I do have a question about heads tho. I just dropped $950 into my 241's having them CNC'd and rebuilt with new valves etc. So I have brand new ported 241's...Well the new (used) motor I'm picking up has 317's I believe on it. I'm reading that 317's are preferred for boosted applications. My question is, are my ported 241's better (or at least as good as) than stock 317's? I'd really hate to have to ditch my 241's I just sunk all that money into.
Absolutely keep the ported 241's over the stock 317's. The reason the 317 is a popular head is the bigger chamber to lower compression for boost and the shared port design with the 243. Stock for stock the 317/243 is better than the 241 but in ported form the 241 will beat either of those heads hands down in stock form.
Your tick may have been a dying lifter. The fact that is stuck around could easily be the exhaust valve closing from a more aggressive cam.
Clean up and sell the 317's. They usually sell relatively well.
Your tick may have been a dying lifter. The fact that is stuck around could easily be the exhaust valve closing from a more aggressive cam.
Clean up and sell the 317's. They usually sell relatively well.
Thread Starter
Launching!
Joined: Apr 2008
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I replaced all of the top end when I rebuilt it. New lifters, rebuilt rockers, etc. Thats why I figure it'd bottom end. Shop I am working with confirmed it to be what they believe to be rod knock. Metal was on the dipstick too so i'm fairly confident in the conclusion.
Thread Starter
Launching!
Joined: Apr 2008
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Absolutely keep the ported 241's over the stock 317's. The reason the 317 is a popular head is the bigger chamber to lower compression for boost and the shared port design with the 243. Stock for stock the 317/243 is better than the 241 but in ported form the 241 will beat either of those heads hands down in stock form.
Your tick may have been a dying lifter. The fact that is stuck around could easily be the exhaust valve closing from a more aggressive cam.
Clean up and sell the 317's. They usually sell relatively well.
Your tick may have been a dying lifter. The fact that is stuck around could easily be the exhaust valve closing from a more aggressive cam.
Clean up and sell the 317's. They usually sell relatively well.