528HP 491TQ.... BUT have you ever seen a graph like this!?!
10-22-2009, 10:17 PM
#1
Restricted User
Thread Starter
iTrader: (36)
Join Date: Sep 2008
Location: Alliance Nebraska
Posts: 1,268
Likes: 0
Received 0 Likes
on
0 Posts
528HP 491TQ.... BUT have you ever seen a graph like this!?! Well i put down 528HP and 491TQ on 14psi, 11.5afr, 22*
BUT the darn car pulls HARD to 5500-5600 then drops to NOTHING! It woud put down ALOT better numbers if it would pull past 5500rpm....
Also on the dyno graph the tq and hp stay almost the same instead of the tq slowly dropping when they cross.... kind of crazy! Never seen a dyno graph like this..... not sure what is wrong.
Springs are good, plugs are tr8's, no KR, not sure what the problem is!!!!!!
ANY ideas??????
http://s721.photobucket.com/albums/w...dynoday014.flv
BUT the darn car pulls HARD to 5500-5600 then drops to NOTHING! It woud put down ALOT better numbers if it would pull past 5500rpm....
Also on the dyno graph the tq and hp stay almost the same instead of the tq slowly dropping when they cross.... kind of crazy! Never seen a dyno graph like this..... not sure what is wrong.
Springs are good, plugs are tr8's, no KR, not sure what the problem is!!!!!!
ANY ideas??????
http://s721.photobucket.com/albums/w...dynoday014.flv
Last edited by 1BAD_LS1; 10-23-2009 at 12:25 AM.
10-22-2009, 10:26 PM
#5
V-A-L-V-E-F-L-O-A-T
Your valve is doing this....
....when its suppose to be seated shut on the back on the valve seat and making compression on the next power stroke.
You need STOUT springs and lighter weight valvetrain components on boosted apps because the intake valve is trying to be blown open by the pressurized inlet tract. You could see 30 lbs or more less seat pressure due to this.
You need 165 on the seat minimum and over 400 open.....heavy rockers are no good....lighter valves are good if possible (on the intake side).
That or somehow your blowing out the spark....you could try reducing your plug gap some.....but my guess is valvefloat.
Take the blower belt off and see how much RPM it will turn cleanly....thats a good test to see if boost and not enough spring pressure is the culprit.
-Tony
EDIT: Looks too dramatic a decline for boost leak....you would have similar boost 200 RPM's before it takes a dump and the graph looks solid. Speaking of that I wanted to congratulate you on what looks to be a beastly combo if you can sort out your higher RPM issues. There could be another 100 HP in this easily based on that curve.....actually make that 150....LOL
Your valve is doing this....
....when its suppose to be seated shut on the back on the valve seat and making compression on the next power stroke.You need STOUT springs and lighter weight valvetrain components on boosted apps because the intake valve is trying to be blown open by the pressurized inlet tract. You could see 30 lbs or more less seat pressure due to this.
You need 165 on the seat minimum and over 400 open.....heavy rockers are no good....lighter valves are good if possible (on the intake side).
That or somehow your blowing out the spark....you could try reducing your plug gap some.....but my guess is valvefloat.
Take the blower belt off and see how much RPM it will turn cleanly....thats a good test to see if boost and not enough spring pressure is the culprit.
-Tony
EDIT: Looks too dramatic a decline for boost leak....you would have similar boost 200 RPM's before it takes a dump and the graph looks solid. Speaking of that I wanted to congratulate you on what looks to be a beastly combo if you can sort out your higher RPM issues. There could be another 100 HP in this easily based on that curve.....actually make that 150....LOL
10-22-2009, 10:35 PM
#6
well its weird that we put 2 shims in the turbo xs rfl bov and picked up 30 to the wheels, boost leak at the bov still? its sealed a lot better tho! we re-shimmed it.
tonys right on the valve float, but i call bs beings you have prc duals.....
maybe your next thing is to shim the bov on the dyno. you need to test that thing seperate, with a separate tube and either a pressurized source or vacuum.
maybe its still on the bov?
tonys right on the valve float, but i call bs beings you have prc duals.....
maybe your next thing is to shim the bov on the dyno. you need to test that thing seperate, with a separate tube and either a pressurized source or vacuum.
maybe its still on the bov?
10-22-2009, 10:45 PM
#7
well its weird that we put 2 shims in the turbo xs rfl bov and picked up 30 to the wheels, boost leak at the bov still? its sealed a lot better tho! we re-shimmed it.
tonys right on the valve float, but i call bs beings you have prc duals.....
maybe your next thing is to shim the bov on the dyno. you need to test that thing seperate, with a separate tube and either a pressurized source or vacuum.
maybe its still on the bov?
tonys right on the valve float, but i call bs beings you have prc duals.....
maybe your next thing is to shim the bov on the dyno. you need to test that thing seperate, with a separate tube and either a pressurized source or vacuum.
maybe its still on the bov?
Also, a standard PRC spring set up improperly (too tall) could certainly be a problem....I would hope he had the PRC upgrade springs like our 8019 versions (the "extreme" version I believe they call them).
I'm certainly very curious what it ultimately turns out to be....I will be watching this thread seeing how things pan out, not to mention how much power this thing lays down when it is sorted out..
-Tony
Trending Topics
10-22-2009, 10:52 PM
#8
Teching In
iTrader: (16)
Join Date: Sep 2007
Location: San Diego, CA
Posts: 35
Likes: 0
Received 0 Likes
on
0 Posts
Aren't there a number of guys out there who boost bone stock long blocks without valve float? I think so.... Are you maintaining fuel pressure the entire pull? Boost steady the entire time? What did you gap your plugs to? Are you running the car in speed density? or blow through MAF?
10-22-2009, 11:08 PM
#10
Restricted User
Thread Starter
iTrader: (36)
Join Date: Sep 2008
Location: Alliance Nebraska
Posts: 1,268
Likes: 0
Received 0 Likes
on
0 Posts
Actually the BOV failing is possible but once again it seems really aggressive and even if it just completely gave up the ghost would power drop to even horrible N/A levels that abruptly.....I guess potentially because the blower is spinning robbing a bunch of power. I didn't even open any of the run logs....is it still making any boost when the curve is falling off a cliff?
Also, a standard PRC spring set up improperly (too tall) could certainly be a problem....I would hope he had the PRC upgrade springs like our 8019 versions (the "extreme" version I believe they call them).
I'm certainly very curious what it ultimately turns out to be....I will be watching this thread seeing how things pan out, not to mention how much power this thing lays down when it is sorted out..
-Tony
Also, a standard PRC spring set up improperly (too tall) could certainly be a problem....I would hope he had the PRC upgrade springs like our 8019 versions (the "extreme" version I believe they call them).
I'm certainly very curious what it ultimately turns out to be....I will be watching this thread seeing how things pan out, not to mention how much power this thing lays down when it is sorted out..
-Tony
I have the PRC dual springs good to .660 with titanium retainers.... they should be good... I would think. I can wait till i figure out the problem... its fast now but man if it pulled all the way through, i should be able to make a 10sec pass pretty easy next spring!
10-22-2009, 11:12 PM
#11
Restricted User
Thread Starter
iTrader: (36)
Join Date: Sep 2008
Location: Alliance Nebraska
Posts: 1,268
Likes: 0
Received 0 Likes
on
0 Posts
Aren't there a number of guys out there who boost bone stock long blocks without valve float? I think so.... Are you maintaining fuel pressure the entire pull? Boost steady the entire time? What did you gap your plugs to? Are you running the car in speed density? or blow through MAF?
Boost fluctuates a few kpa throughout the pull (logs)
ya it an SD tune.
plugs are gapped at 22, and are tr8's (maybee to cold????)
10-23-2009, 12:00 AM
#14
TECH Resident
iTrader: (24)
Join Date: Jan 2007
Location: Rhode Island
Posts: 838
Likes: 0
Received 0 Likes
on
0 Posts
i dont think it could be valve float because i had brand new patriot spings and all that other stuff and both on 5psi and 10psi when i had my turbo dropped off like that also ....no boost leaks nothing wrong but the car still pulled like a SOB past 5k where it started to drop off
10-23-2009, 12:12 AM
#15
i cant open any of your log files (still working on this hpt thing...)
but whoever is skilled should check them out. you can clearly see in the log file where the motor 'revs slower' past 5300. it climbs hard then levels off, you can also notice it in the movie clips, just where the car climbs to 5300 fast then takes forever to get to 6400.
but whoever is skilled should check them out. you can clearly see in the log file where the motor 'revs slower' past 5300. it climbs hard then levels off, you can also notice it in the movie clips, just where the car climbs to 5300 fast then takes forever to get to 6400.
10-23-2009, 01:05 PM
#16
i would still check for boost leaks, i dont know of anything "showing" boost leaks. best thing to do is shoot compressed air through out the intercoolerpiping, anything that holds boost. maybe leaking wastegate?
10-23-2009, 02:39 PM
#17
Didn't read any replies, but that's valve float.
I would wager you have stock or LS6 valve springs too, though you should not.
If this is an STS car it may just be choking up top as they all do from too tight of an A/R, but it sure LOOKS like all of the valve float that I have seen.
I would wager you have stock or LS6 valve springs too, though you should not.
If this is an STS car it may just be choking up top as they all do from too tight of an A/R, but it sure LOOKS like all of the valve float that I have seen.
10-23-2009, 04:57 PM
#20
11 Second Club
iTrader: (20)
Join Date: Oct 2006
Location: Virginia
Posts: 3,131
Likes: 0
Received 0 Likes
on
0 Posts
one of 2 things...
valve float "doubting this with the duals"
ore your blowing out the spark....im leaning towards this thats a cool *** plug id throw a 7 range plug in it gapped around .028-.030 and see what happens....
i used to fool with turbo dsm's and put together a couple of turbo 2.3 fox bodies...and im leaning towards blowing out the flame....
to many bossted cars with stock or ls6 springs....doing just fine....
your build is similar to what im doing except im using ported heads and a mp gt45...
nice numbers regardless man...the 5.3s are amazing
valve float "doubting this with the duals"
ore your blowing out the spark....im leaning towards this thats a cool *** plug id throw a 7 range plug in it gapped around .028-.030 and see what happens....
i used to fool with turbo dsm's and put together a couple of turbo 2.3 fox bodies...and im leaning towards blowing out the flame....
to many bossted cars with stock or ls6 springs....doing just fine....
your build is similar to what im doing except im using ported heads and a mp gt45...
nice numbers regardless man...the 5.3s are amazing