GMPP claims 30-40hp from breathing windows on the LS7?
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GMPP claims 20-30hp from breathing windows on the LS7?
GMPP claims the bay-to-bay breathing windows on the LS7 gained them 20-30hp over previous LS engines. They used them in the new LSX block also.
Is this for real? Page 31 in the Feb. GMHTP, but I'm sure its on the net too.
Is this for real? Page 31 in the Feb. GMHTP, but I'm sure its on the net too.
Last edited by BlackHawk T/A; 02-08-2007 at 05:49 PM.
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Originally Posted by BlackHawk T/A
GMPP claims the bay-to-bay breathing windows on the LS7 gained them 30-40hp over previous LS engines. They used them in the new LSX block also.
Is this for real? Page 31 in the Feb. GMHTP, but I'm sure its on the net too.
Is this for real? Page 31 in the Feb. GMHTP, but I'm sure its on the net too.
.
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Originally Posted by BlackHawk T/A
I find the claim a bit far-fetched. I wanted to see if anyone else knew about it.
Yeah I wonder how they came up with that number. I am going to find out and I will let you know.
Based on conversations with people who have experiance I have heard in the area of 10 horsepower.
I would say that there would be a lot of factors such as stroke, RPM range that would effect the ultimate horsepower gain verses a block that doesn't have the windows.
Again when I find out the source I will post a update.
Thanks
Robin
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I think the fact that there are 427's out there for the past 6 years using LS1/LS6 blocks and LS1/LS6 heads and LS1/LS6 intakes that have more HP than the LS7 427, there AIN'T no damn way that this one thing creates 30-40 extra HP by itself. Common sense really. And there isn't 30-40 HP more anyway, it just isn't there. If it were true the LS7 427 would be laying down 530-540 RWHP.
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Update
As I said I talked to my contacts at GMPP. First I have not seen the article but I can say that it is true. Well the word I got was that is was "close to 30 Horsepower". That is from the guys who worked on the development of the LS7.
Bay to Bay breathing is something that I only learned about about 2 years ago. My Engine guy Jeff Steahly had talked about drilling the bulkheads in my 306 Ford Real Street engine. Jeff had been making this modification on many of his customers NHRA Super Stock engines with positive results. At the time it was very hush hush. He said that on the dyno they typicallly saw about 10 horsepower over previous baseline numbers. Remember this was on small block chevy engines. Small stroke engines.
On the LS7 you have a lot more volume of air that is being pumped as the pistons move up and down. Drilling a hole in the bulkhead was worth power.
Now as you can imagine this is not a modification for the timid. Better to buy a block with this done.
On the Ford engines there is an oil passage that is very close at the front bulkhead. It becomes a matter of how much do you want to remove before you risk the strength of the bulkhead. Us racers are used to taking things to the limit, finding the weak spot then backing off a little bit.
Most people are not in that type of situation.
Unless your engine builder knows the risks I would not recomend you making this modification.
It is another advantage of the LS7 block over a re sleeved LS2.
If you notice the new GMPP LSX Block has passages around the mains to promote Bay to Bay breathing.
So yes this story is true. 30 horsepower in a large bore stroke deal.
Have a great day!
Robin
Bay to Bay breathing is something that I only learned about about 2 years ago. My Engine guy Jeff Steahly had talked about drilling the bulkheads in my 306 Ford Real Street engine. Jeff had been making this modification on many of his customers NHRA Super Stock engines with positive results. At the time it was very hush hush. He said that on the dyno they typicallly saw about 10 horsepower over previous baseline numbers. Remember this was on small block chevy engines. Small stroke engines.
On the LS7 you have a lot more volume of air that is being pumped as the pistons move up and down. Drilling a hole in the bulkhead was worth power.
Now as you can imagine this is not a modification for the timid. Better to buy a block with this done.
On the Ford engines there is an oil passage that is very close at the front bulkhead. It becomes a matter of how much do you want to remove before you risk the strength of the bulkhead. Us racers are used to taking things to the limit, finding the weak spot then backing off a little bit.
Most people are not in that type of situation.
Unless your engine builder knows the risks I would not recomend you making this modification.
It is another advantage of the LS7 block over a re sleeved LS2.
If you notice the new GMPP LSX Block has passages around the mains to promote Bay to Bay breathing.
So yes this story is true. 30 horsepower in a large bore stroke deal.
Have a great day!
Robin
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Originally Posted by 67camaro
LS6 Blocks also have them. LS1's dont.
No, only LS7 and GMPP LSX blocks.
I don't know about the other aftermarket blocks.
Robin
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I laos remember reading that the LS6 had windows for better bay-to-bay breathing when they were released. I couldnt find any GM releases, but here are a couple things I found.
http://www.idavette.net/hib/ls6/page3.htm
http://www.dw1977.cz28.com/whats_new.html
I also remember big power claims then, in the area of 20 hp.
http://www.idavette.net/hib/ls6/page3.htm
http://www.dw1977.cz28.com/whats_new.html
I also remember big power claims then, in the area of 20 hp.
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Originally Posted by 67camaro
LS6 Blocks also have them. LS1's dont.
I gotta run up the flag on that one... ... Yes the windows are the difference in the LS1 block and the LS6 block and I beleive those changes were incorporated into all the LS serise engines that came after that..LS2 ect. ect. I have major doubts that it would produce that much of a horse power gain..if so the LS6 cam and heads with light weight hollow stem valves were only good for 15 HP in the 405 HP version and even less in the 385 HP version..
Last edited by slt200mph; 02-08-2007 at 11:04 AM.
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Originally Posted by slt200mph
I gotta run up the flag on that one... ... Yes the windows are the difference in the LS1 block and the LS6 block and I beleive those changes were incorporated into all the LS serise engines that came after that..LS2 ect. ect. I have major doubts that it would produce that much of a horse power gain..if so the LS6 cam and heads with light weight hollow stem valves were only good for 15 HP in the 405 HP version and even less in the 385 HP version..
It looks like I need to got back and take a look.
Robin
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Originally Posted by WECIV
Google LS6 Breathing Windows and you will find that the LS6 did have these things. Can anyone provide a diagram on how these things work? Thanks!!!
W
W
In the picture you can see where the crank mains are and that slit above it is the window (not the vertical one, I am pretty sure that is a water jacket).
Last edited by mzoomora; 02-08-2007 at 05:04 PM.
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Something else to consider is that with high crankcase vacuum found in most max effort engines with dry sumps and vacuum pumps this should even make less of a difference. I believe I saw somewhere that the NASCAR engine builders are now partitioning off the oil pans in an effort to decrease windage travel in the lower ends. These engines would have at least 1 dry sump pickup in each section though.