Valve float?
11-02-2008, 07:05 PM
#1
TECH Regular
Thread Starter
Join Date: Dec 2004
Location: Alpharetta, Ga
Posts: 440
Likes: 0
Received 0 Likes
on
0 Posts
Valve float? Mods are listed in my profile, but the baisics are bolt ons and a Vengeance Racing cam.
I want to draw your attention to the tq curve at 4500rpm and the hp curve at 5200rpm. You will notice both curves climb until those points on the graph and then very obviously "flat line". I have been told this is the restriction posed by the stock, unported LS3 intake manifold by a bigtime vette guy that just happened to be at the dyno while I was there..
The reason why I am posting this is I just want to make sure this isn't valve float. I am running Comp 921's, hardened pushrods, and the setup has roughly 7k miles on it with majority being casual, low rpm driving.
FWIW, the tune is absolutely spot on. The lower numbers represent my initial tune. The higher numbers represent the tune 32 iterations later, after getting the VE and MAF curves really dialed in using my wideband and the help of a good buddy
I want to draw your attention to the tq curve at 4500rpm and the hp curve at 5200rpm. You will notice both curves climb until those points on the graph and then very obviously "flat line". I have been told this is the restriction posed by the stock, unported LS3 intake manifold by a bigtime vette guy that just happened to be at the dyno while I was there..
The reason why I am posting this is I just want to make sure this isn't valve float. I am running Comp 921's, hardened pushrods, and the setup has roughly 7k miles on it with majority being casual, low rpm driving.
FWIW, the tune is absolutely spot on. The lower numbers represent my initial tune. The higher numbers represent the tune 32 iterations later, after getting the VE and MAF curves really dialed in using my wideband and the help of a good buddy
11-03-2008, 08:55 AM
#3
TECH Regular
Thread Starter
Join Date: Dec 2004
Location: Alpharetta, Ga
Posts: 440
Likes: 0
Received 0 Likes
on
0 Posts
www.mmpdragracing.com I just bought some DR's for her, so I hope to try and get some good cam times next weekend as long as the weather cooperates.
After doing some searching, it appears I am ok. From what I have seen on graphs with valve float, the car will immediately lose significant power and the graph will become very wavy. Those who are familiar with valve float can comment on this to see if I am correct.
After doing some searching, it appears I am ok. From what I have seen on graphs with valve float, the car will immediately lose significant power and the graph will become very wavy. Those who are familiar with valve float can comment on this to see if I am correct.
11-03-2008, 10:26 AM
#4
Not valve float. The first torque peak at 4600 rpm is dictated by the cross section area and tuned runner length of your intake manifold and the second peak at 5600 rpm is dictated by the valve events of your cam. Basically, you are running a cam that is forcing a later power peak than what the intake manifold was designed for. Seems to have worked OK in your case. Strong numbers.
__________________
2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2018 Cadillac Escalade 6.2L A10 Pat G tuned.
LS1,LS2,LS3,LS7,LT1 Custom Camshaft Specialist For custom camshaft help press here.
Custom LSX tuning in person or via email press here.
2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2018 Cadillac Escalade 6.2L A10 Pat G tuned.
LS1,LS2,LS3,LS7,LT1 Custom Camshaft Specialist For custom camshaft help press here.
Custom LSX tuning in person or via email press here.
11-03-2008, 09:59 PM
#6
TECH Fanatic
iTrader: (1)
Join Date: May 2004
Location: Mesa, Arizona
Posts: 1,691
Likes: 0
Received 0 Likes
on
0 Posts
Intake "signing off". Had something similar happen to my car when I was H/C with a fast 90/90. HP flat lined @ 6k RPMs and carried all the way to 6800.
Very nice power!
Very nice power!
