Why 5 and 7
Le Mans Master
Joined: May 2006
Posts: 9,993
Likes: 1,136
From: League City Tx
That is the Million Dollar question that know one knows the answer to.... But damn sure on LS1/LS6s, #5/7 will be the ones to go....
Some think it has something to do with coolant circulation issues and steam pockets in the heads around those cylinders.... Some think it is due to intake manifold design.
You don't seem to hear about the 5.3s lunching #5/7 NEAR as often/common as LS1s/6s.
Mine killed #5/7 with a good tune, meth and only 10 psi.
But hey, "stock motors are good for 700hp" so.......
Some think it has something to do with coolant circulation issues and steam pockets in the heads around those cylinders.... Some think it is due to intake manifold design.
You don't seem to hear about the 5.3s lunching #5/7 NEAR as often/common as LS1s/6s.
Mine killed #5/7 with a good tune, meth and only 10 psi.
But hey, "stock motors are good for 700hp" so.......
Melting Slicks
Joined: Mar 2005
Posts: 2,225
Likes: 42
From: Okinawa
"The intake on the LS1 or LS6 when reversed (installed like the front wheel drive) still burns up #7 first. The intake can be flipped with 10 02 sensors and the afr on each cylinder/bank does not change within the error of the sensor.
Kurt"
Copied from another forum.
Kurt"
Copied from another forum.
Team Owner
Joined: Jan 2007
Posts: 29,065
Likes: 1,839
From: cookeville tennessee
That is the Million Dollar question that know one knows the answer to.... But damn sure on LS1/LS6s, #5/7 will be the ones to go....
Some think it has something to do with coolant circulation issues and steam pockets in the heads around those cylinders.... Some think it is due to intake manifold design.
You don't seem to hear about the 5.3s lunching #5/7 NEAR as often/common as LS1s/6s.
Mine killed #5/7 with a good tune, meth and only 10 psi.
But hey, "stock motors are good for 700hp" so.......
Some think it has something to do with coolant circulation issues and steam pockets in the heads around those cylinders.... Some think it is due to intake manifold design.
You don't seem to hear about the 5.3s lunching #5/7 NEAR as often/common as LS1s/6s.
Mine killed #5/7 with a good tune, meth and only 10 psi.
But hey, "stock motors are good for 700hp" so.......
That had to hurt... Robert
Melting Slicks
Joined: Jul 2004
Posts: 2,844
Likes: 144
From: Northern Ireland
Melting Slicks
Joined: Feb 2006
Posts: 2,163
Likes: 5
From: Houston
The 5.3's suffer the same fate along with the gen4's. Regardless of the fact that the Achilles heal of these motors, it is detonation occurring on #7 that kills it. I've always gone overly conservative on my tunes knowing that #7 isn't nearly as happy as the dyno, knock sensors, wb say the engine is.
My stock motor was good to 750rwhp.
I don't know why it is always #5 and #7 though. I don't think anyone does.
My stock motor was good to 750rwhp.
I don't know why it is always #5 and #7 though. I don't think anyone does.
That is the Million Dollar question that know one knows the answer to.... But damn sure on LS1/LS6s, #5/7 will be the ones to go....
Some think it has something to do with coolant circulation issues and steam pockets in the heads around those cylinders.... Some think it is due to intake manifold design.
You don't seem to hear about the 5.3s lunching #5/7 NEAR as often/common as LS1s/6s.
Mine killed #5/7 with a good tune, meth and only 10 psi.
But hey, "stock motors are good for 700hp" so.......
Some think it has something to do with coolant circulation issues and steam pockets in the heads around those cylinders.... Some think it is due to intake manifold design.
You don't seem to hear about the 5.3s lunching #5/7 NEAR as often/common as LS1s/6s.
Mine killed #5/7 with a good tune, meth and only 10 psi.
But hey, "stock motors are good for 700hp" so.......
Melting Slicks
Joined: Jul 2004
Posts: 2,844
Likes: 144
From: Northern Ireland
The 5.3's suffer the same fate along with the gen4's. Regardless of the fact that the Achilles heal of these motors, it is detonation occurring on #7 that kills it. I've always gone overly conservative on my tunes knowing that #7 isn't nearly as happy as the dyno, knock sensors, wb say the engine is.
My stock motor was good to 750rwhp.
I don't know why it is always #5 and #7 though. I don't think anyone does.
My stock motor was good to 750rwhp.
I don't know why it is always #5 and #7 though. I don't think anyone does.
There may be a higher proportion, but it is not limited to them
And unless you're listening for knock on a per cylinder basis, and monitoring EGT and AFR on a per cylinder basis, you will never truly know how happy cyl 7 is.
You're just taking an average of either each bank or all 8 depending on how much you're monitoring.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Melting Slicks
Joined: Feb 2006
Posts: 2,163
Likes: 5
From: Houston
Well Ive blown engines, and seen other blown engines. And it certainly is not 5/7 every time.
There may be a higher proportion, but it is not limited to them
And unless you're listening for knock on a per cylinder basis, and monitoring EGT and AFR on a per cylinder basis, you will never truly know how happy cyl 7 is.
You're just taking an average of either each bank or all 8 depending on how much you're monitoring.
There may be a higher proportion, but it is not limited to them
And unless you're listening for knock on a per cylinder basis, and monitoring EGT and AFR on a per cylinder basis, you will never truly know how happy cyl 7 is.
You're just taking an average of either each bank or all 8 depending on how much you're monitoring.
Of course it is not always the #5 or #7, but it is the majority. Any shop willing to admit to the engines their customers have popped that were tuned by them would tell you that. :crickets: