Can a 370 outperform a 383?
LMAO! You missed the point smart guy. I can totally understand whats being said here you guys are limiting the 383's output by your heads choices not me.
An engine is an air pump and the more air your put through it the more power you make. Can we agree on that?
Here we'll match up the bigger bore and stroke to make it equal in your minds 4.100 bore x 3.622 stroke... so now we have an even bigger bore and the same stroke. Which makes more power??
PUT THE PROPER HEADS ON IT!
So what are these magic cyclinder heads that you have in mind that will flow more on a 3.9" bore than a 4" bore?
99blancoSS It's an interesting thread and we might learn something new...so I'll play the game....what's the most airflow you can get with the head of your choice on a 3.9 bore? What's that same head flow on a 4.030 inch bore? What do those heads flow thru the intake being used with the respective bores?
Are you serious? It is because of the engine architecture (bore centerline) If you have ever seen an LS7 shortblock or built one you would see the sleeves are pretty thin between cylinders and there is NO room to make the bore larger on stock sleeves. Like I said before stick to wires
I didnt say one head will flow more than another at all anywhere, what I said what feed the 383 the proper air and it will make more power.
Are you serious? It is because of the engine architecture (bore centerline) If you have ever seen an LS7 shortblock or built one you would see the sleeves are pretty thin between cylinders and there is NO room to make the bore larger on stock sleeves. Like I said before stick to wires
How much air does a 370 consume vs how much does a 383 consume?
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Launching!
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I keep thinking some fellas are stuck in the "There's no replacement for displacement" adage our father's taught us when we were young. Though displacement surely helps in making power, the old adage should be corrected to better represent our times.
It should read:
"There's no replacement for cfm."
...which is what this thread boils down to, and is why I started it.
It should read:
"There's no replacement for cfm."
...which is what this thread boils down to, and is why I started it.
I totally agree, the more air you can put through the more power you will make.
Put an equally efficient for both top end on. I've tried to say that over and over. Its all about how much air you can put through.
Put an equally efficient for both top end on. I've tried to say that over and over. Its all about how much air you can put through.
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Teching In
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When thinking of the engine as strictly an air pump for comparisons, one must compare apples to apples. While it is theoretically possible for a 383 to build more power than a 370, this would only be accomplished (for certain) if both engines were built off of the same bore, and each were given a respective stroke to meet the cubic inches required. Given this and all other complimentary parts being equal the 383 would most likely make more power.
However, this is not the case and I believe 9 out of 10 times the 370 would beat the 383. I believe this for three reasons: valve shrouding would be better controlled on the 370, the 370 I would think would have less reciprocating mass than theh 383 because of the stroke difference, and 383 available head choices would be limit to its bore.
However, this is not the case and I believe 9 out of 10 times the 370 would beat the 383. I believe this for three reasons: valve shrouding would be better controlled on the 370, the 370 I would think would have less reciprocating mass than theh 383 because of the stroke difference, and 383 available head choices would be limit to its bore.
Head selection for available bore size makes a huge difference here!! Get the best head for the 383, and get the best for the 370. The 370 will make more and better power.
Blanco: Surely in all your years of testing this stuff you've seen the difference bore size makes on head flow!
Blanco: Surely in all your years of testing this stuff you've seen the difference bore size makes on head flow!
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383 cu.in at 6000 rpms = 664.9 CFM
Both of these figures are theoretical air flow which takes into account 100% volumetric efficiency. Cylinder heads have alot to do with VE. Now take a cylinder head that flows 300 cfm on a 3.9 bore and 320 cfm on a 4.0 bore. 300cfm/320cfm = 0.94 (94%) Reduce the VE of the 383cu.in to 0.94 instead of 1.00.
370 cu.in at 6000 rpms = 642.4 CFM
383 cu.in at 6000 rpms = 623.4 CFM
I have built a few engines in my day, and not just GM Gen III/IV.
The point you are missing is the same cylinder head on a larger bore will flow more CFM at a given RPM and thus make more power. There is no MAGIC BULLET cylinder head that flows more CFM on a smaller bore.
Last edited by ChiTownHustler; Dec 10, 2008 at 10:43 AM.
370 cu.in at 6000 rpms = 642.4 CFM
383 cu.in at 6000 rpms = 664.9 CFM
Both of these figures are theoretical air flow which takes into account 100% volumetric efficiency. Cylinder heads have alot to do with VE. Now take a cylinder head that flows 300 cfm on a 3.9 bore and 320 cfm on a 4.0 bore. 300cfm/320cfm = 0.94 (94%) Reduce the VE of the 383cu.in to 0.94 instead of 1.00.
370 cu.in at 6000 rpms = 642.4 CFM
383 cu.in at 6000 rpms = 623.4 CFM
I have built a few engines in my day, and not just GM Gen III/IV.
The point you are missing is the same cylinder head on a larger bore will flow more CFM at a given RPM and thus make more power. There is no MAGIC BULLET cylinder head that flows more CFM on a smaller bore.
383 cu.in at 6000 rpms = 664.9 CFM
Both of these figures are theoretical air flow which takes into account 100% volumetric efficiency. Cylinder heads have alot to do with VE. Now take a cylinder head that flows 300 cfm on a 3.9 bore and 320 cfm on a 4.0 bore. 300cfm/320cfm = 0.94 (94%) Reduce the VE of the 383cu.in to 0.94 instead of 1.00.
370 cu.in at 6000 rpms = 642.4 CFM
383 cu.in at 6000 rpms = 623.4 CFM
I have built a few engines in my day, and not just GM Gen III/IV.
The point you are missing is the same cylinder head on a larger bore will flow more CFM at a given RPM and thus make more power. There is no MAGIC BULLET cylinder head that flows more CFM on a smaller bore.
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Launching!
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But will it be enough to overtake a 383? Will the head flow potential of the 370 be enough to make up the displacement difference? That is the crux of this thread.
I think you might be the one not understanding whats going on here. A cylinder head doesn't just automatically flow the same air on the 383 as it does on the 370 just because you want it to, or because "someone massaged it to"
It's just not that simple. The bore is whats not only creating better head flow, it's also giving more room for unshrouding valves & allowing a bigger runner / valve combo.
I'm trying not to hammer on you Blanco, but give me a break....
If the 383 was all bore it would easily outperform the 370, the problem is ls1 383s are 4" stroke small bore.
Let me give you one more example. You take a 4.125" bore motor with 3.622 stroke and dyno it next to a 4.125" stroke motor with 3.622 bore. The 4.125" bore motor would be able to run a 400cfm LS7 head & make huge power. The 3.622 bore motor would be stuck with a tinny valve like in a 4.8l/5.3l head. The bore motor would make so much more power it's not even funny. Not even remotely funny...
And I don't have to show you a 545rwhp 370, I have a 346 that makes that
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Jason
Co-Owner, Texas Speed & Performance, Ltd.
2005 Twin Turbo C6
404cid Stroker, 67mm Twins
994rwhp/902lb ft @ 22 psi (mustang dyno) www.Texas-Speed.com
Jason
Co-Owner, Texas Speed & Performance, Ltd.
2005 Twin Turbo C6
404cid Stroker, 67mm Twins
994rwhp/902lb ft @ 22 psi (mustang dyno) www.Texas-Speed.com
No doubt the 370 can make more power if your willing to buy all the parts to complete the combo. That being said if you have a existing pair of heads, or a existing camshaft that might limit the bore, then the 383 might be just fine.
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Jason
Co-Owner, Texas Speed & Performance, Ltd.
2005 Twin Turbo C6
404cid Stroker, 67mm Twins
994rwhp/902lb ft @ 22 psi (mustang dyno) www.Texas-Speed.com
Jason
Co-Owner, Texas Speed & Performance, Ltd.
2005 Twin Turbo C6
404cid Stroker, 67mm Twins
994rwhp/902lb ft @ 22 psi (mustang dyno) www.Texas-Speed.com
this guy would school you in automotive knowledge, please dont bash what you dont understand.
I dont want to bash any sponsor... because they are the reason that this site is what it is today.... but Blanco came in here all cocky and hard-headed and it someone like Jason @ TSP would have never stepped up, then people might have actually believed the bad-info that was being spread.
It's no worries guys, we're all here to learn & enjoy the LS engines!! 
__________________
Jason
Co-Owner, Texas Speed & Performance, Ltd.
2005 Twin Turbo C6
404cid Stroker, 67mm Twins
994rwhp/902lb ft @ 22 psi (mustang dyno) www.Texas-Speed.com
Jason
Co-Owner, Texas Speed & Performance, Ltd.
2005 Twin Turbo C6
404cid Stroker, 67mm Twins
994rwhp/902lb ft @ 22 psi (mustang dyno) www.Texas-Speed.com
I dont want to bash any sponsor... because they are the reason that this site is what it is today.... but Blanco came in here all cocky and hard-headed and it someone like Jason @ TSP would have never stepped up, then people might have actually believed the bad-info that was being spread.