Notices
Dynamometer Results & Comparisons Dyno Records | Dyno Discussion | Dyno Wars

LS3 1.85 Rocker Test

 
Old 09-17-2018, 07:22 AM
  #1  
10 Second Club
Thread Starter
 
lazerlemonta's Avatar
 
Join Date: Feb 2004
Location: VA
Posts: 403
Default LS3 1.85 Rocker Test

Been trying to figure out the dip at 6600 in my dyno graphs. So I went Friday and did a test on the 1.85s and swapped back to stock rockers on the dyno (it was hot) and here are the results. Red is yellaterra 1.85 and blue is stock. I have PSI1511 springs and titanium retainers on it. Mods are in signature.
lazerlemonta is offline  
Old 09-17-2018, 07:28 AM
  #2  
TECH Senior Member
iTrader: (26)
 
ddnspider's Avatar
 
Join Date: Aug 2004
Location: FL
Posts: 8,186
Default

That gain above 6k with the 1.85's is pretty good, until 6600. Too much rocker weight to control them properly at that rpm with those springs?
ddnspider is offline  
Old 09-17-2018, 08:06 AM
  #3  
10 Second Club
Thread Starter
 
lazerlemonta's Avatar
 
Join Date: Feb 2004
Location: VA
Posts: 403
Default

Originally Posted by ddnspider View Post
That gain above 6k with the 1.85's is pretty good, until 6600. Too much rocker weight to control them properly at that rpm with those springs?
Thats the best we can come up with. These rockers are only good to 400lbs open spring pressure. I have heard they do fin up to 450lbs. I am currently looking for the ideal spring to swap and keep for a cam change. Need a decent amount of seat pressure but not to much to pop the head of a valve off lol
lazerlemonta is offline  
Old 09-17-2018, 08:11 AM
  #4  
TECH Senior Member
iTrader: (26)
 
ddnspider's Avatar
 
Join Date: Aug 2004
Location: FL
Posts: 8,186
Default

Originally Posted by lazerlemonta View Post
Thats the best we can come up with. These rockers are only good to 400lbs open spring pressure. I have heard they do fin up to 450lbs. I am currently looking for the ideal spring to swap and keep for a cam change. Need a decent amount of seat pressure but not to much to pop the head of a valve off lol
I gotcha. It's interesting that it looks like the stocker's made more power down low, but the 1.85's gained ~15whp up top.
ddnspider is offline  
Old 09-17-2018, 08:15 AM
  #5  
10 Second Club
Thread Starter
 
lazerlemonta's Avatar
 
Join Date: Feb 2004
Location: VA
Posts: 403
Default

Originally Posted by ddnspider View Post
I gotcha. It's interesting that it looks like the stocker's made more power down low, but the 1.85's gained ~15whp up top.
That is in fact what happened and has us all scratching our heads. Typically they make more power everywhere.
lazerlemonta is offline  
Old 09-17-2018, 08:23 AM
  #6  
TECH Senior Member
iTrader: (26)
 
ddnspider's Avatar
 
Join Date: Aug 2004
Location: FL
Posts: 8,186
Default

Just throw a cam in it and be done
ddnspider is offline  
Old 09-17-2018, 08:40 AM
  #7  
10 Second Club
Thread Starter
 
lazerlemonta's Avatar
 
Join Date: Feb 2004
Location: VA
Posts: 403
Default

Originally Posted by ddnspider View Post
Just throw a cam in it and be done
Not enough time to make that happen for the november rental lol
lazerlemonta is offline  
Old 09-17-2018, 08:43 AM
  #8  
TECH Senior Member
iTrader: (26)
 
ddnspider's Avatar
 
Join Date: Aug 2004
Location: FL
Posts: 8,186
Default

Originally Posted by lazerlemonta View Post
Not enough time to make that happen for the november rental lol
Plenty of time! Weekend and a 6 pack lol.
ddnspider is offline  
Old 09-17-2018, 08:56 AM
  #9  
11 Second Club
 
sxc Z28's Avatar
 
Join Date: Aug 2016
Location: Indiana
Posts: 323
Default

Debil rawkers gone debil.
sxc Z28 is online now  
Old 09-17-2018, 09:11 PM
  #10  
TECH Addict
iTrader: (6)
 
Johnnystock's Avatar
 
Join Date: Feb 2007
Location: Canada
Posts: 2,598
Default

Very good info, nice back to back test.
Johnnystock is offline  
Old 09-18-2018, 12:15 PM
  #11  
Launching!
iTrader: (4)
 
Join Date: Oct 2008
Posts: 276
Default

Not really a great match for the FAST you just got. Stock rockers and the FAST would probably be worth more ET on the track.

Very strange they're down on power below 6000...that's a significant loss. They lost everywhere about what I'd expect them to gain??
spanks13 is offline  
Old 09-18-2018, 12:35 PM
  #12  
10 Second Club
Thread Starter
 
lazerlemonta's Avatar
 
Join Date: Feb 2004
Location: VA
Posts: 403
Default

Originally Posted by spanks13 View Post
Not really a great match for the FAST you just got. Stock rockers and the FAST would probably be worth more ET on the track.

Very strange they're down on power below 6000...that's a significant loss. They lost everywhere about what I'd expect them to gain??
Considering I am never below 5k I dont know how the rockers would not be faster on track. The gain up top is a solid 10-12 until 6600.
lazerlemonta is offline  
Old 09-18-2018, 01:15 PM
  #13  
11 Second Club
 
SoFla01SSLookinstok's Avatar
 
Join Date: Mar 2012
Location: South Florida
Posts: 1,473
Default

Nice test. Also thought weird the gain wasn't through the whole rpm band.
SoFla01SSLookinstok is offline  
Old 09-18-2018, 05:15 PM
  #14  
Launching!
iTrader: (4)
 
Join Date: Oct 2008
Posts: 276
Default

Originally Posted by lazerlemonta View Post
Considering I am never below 5k I dont know how the rockers would not be faster on track. The gain up top is a solid 10-12 until 6600.
Maybe I wasn't too clear - I meant that with the new short runner fast you're going to run you'll want to be shifting 7500-ish. This thing is taking a nose dive above 6600. Stable valvetrain and the short runner intake would probably run better on track than the 1.85's keeping it out of valvefloat. The fast intake makes less power until ~6000 rpm on an ls3.
spanks13 is offline  
Old 09-18-2018, 05:24 PM
  #15  
Launching!
iTrader: (4)
 
Join Date: Oct 2008
Posts: 276
Default

Try shimming up your valvesprings? More seat pressure would probably help with the instability.
spanks13 is offline  
Old 09-18-2018, 09:18 PM
  #16  
TECH Fanatic
iTrader: (1)
 
Che70velle's Avatar
 
Join Date: Jan 2012
Location: Dawsonville Ga.
Posts: 1,910
Default

How much time on the 1511’s? The YT’s are gonna need a little more spring than the Oem rockers, as you know.
Che70velle is offline  
Old 09-19-2018, 11:03 AM
  #17  
TECH Senior Member
iTrader: (26)
 
kinglt-1's Avatar
 
Join Date: Jul 2005
Location: Ft. Wayne, IN
Posts: 5,556
Default

Originally Posted by ddnspider View Post
That gain above 6k with the 1.85's is pretty good, until 6600. Too much rocker weight to control them properly at that rpm with those springs?
SLP 1.85's don't weigh any more then stock. I'm gonna guess needs more valve spring or shim the current ones.
kinglt-1 is offline  
Old 09-19-2018, 11:28 AM
  #18  
TECH Senior Member
iTrader: (26)
 
ddnspider's Avatar
 
Join Date: Aug 2004
Location: FL
Posts: 8,186
Default

Originally Posted by kinglt-1 View Post
SLP 1.85's don't weigh any more then stock. I'm gonna guess needs more valve spring or shim the current ones.
It didn't nose over with stock rockers....so what's the difference if its not rocker weight, simply the increased ratio?
ddnspider is offline  
Old 09-19-2018, 02:34 PM
  #19  
TECH Fanatic
iTrader: (1)
 
Kfxguy's Avatar
 
Join Date: Apr 2017
Posts: 1,351
Default

I know you probably dont want to spend this kind of money, but to gain back the stability that you lost, your going to have to lighten up the intake valves and valve springs if you dont want to find lighter rockers. the weight of the springs themselves actually makes a difference. I'm sure you already have titanium retainers, if not then definitely get some. the little things add up. Before pulling the heads, try the external things.
Kfxguy is offline  
Old 09-19-2018, 08:32 PM
  #20  
TECH Enthusiast
 
8.Lug's Avatar
 
Join Date: Nov 2016
Location: PNW
Posts: 712
Default

Thatís clearly a loss of valvetrain control up top. But what are your cam specs? Higher ratio rockers do increase actual valve duration slightly - I wonder if extra overlap is whatís causing that power loss - and that is a significant power loss.
8.Lug is offline  

Thread Tools
Search this Thread

About Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: