LS/T56 rear suspension upgrades for drag strip launch

[81cutlass]

I know you dont have a mustang rear, but the info might be relevent. Changing the upper control arm perches messes stuff up if its not perfect. Changing the upper control arm mounts changes the instant center and wheel hops does stuff ect.

He had big problems with getting it not to wheel hop.

 

[zildjian4life218]

Great choice on the cam and gear, can't understand why it would bog. Are you running a carb? If I am guessing right your going through the traps at about 113mph. What are the numbers on the 1/4 mi run - guessing again your running 12.0's

It is an LS3 intake with a MS3X megasquirt standalone ECU running full sequential. Times bounced around the 12.70s but mph was pretty consistent at 113-114. Also it was very lean at WOT so there should be more MPH to get out of it once I figure out the fuel issue

 

[lilbowtie]

Have you monitored AFR during one of the runs?? It would be great to know where your at. Your putting out 375 Hp and your 60's should be 1.6 which would put you around 12.0. Sounds like you have some new combo testing and tuning.

 

[zildjian4life218]

Funny you should mention that. I actually have a forum post over at msextra.com which is the forum boards for the MegaSquirt Extra firmware that I am running. AFR is reporting in the high 12s but my plugs are coming out white. They think there is a calibration issue which is causing the car to run as lean as it is. I also think I am running out of fuel pump or something. My VE cells are going way over 100 at WOT at 4000+rpm and plugs are white.

Here is the link if you want to see what the plugs look like after 400+ miles and 4 or 5 1/4mile passes
http://www.msextra.com/forums/viewtopic.php?f=134&t=63300&p=479069#p479069

 

[lilbowtie]

I am not a plug reader and when you pull the plugs matters. The carbon on the base ring is indicating rich. Your ground strap is showing no color change indicating the heat range is too high and possibly too much timing. The bone white porcelain is indicating too much timing and lean @ WOT. that's my 2 cents. I'm not an electronic tuner and watched my buddy suffer through it - there is a lot going on. I use an Innovated system with a down track recorder and it tells me where I'm at from start to finish.

 

[marcar1993]

I will have to see if I can dig up some pics but it has a flat 3/16" plate that goes from each axle tube across the top and the UCA mounts are welded to it. I got a g body 9" bracket kit from ebay and trimed them to ft the 8.8 and welded them on. I am guessing they are taller than the factory ones. So maybe my IC is way off? Also I do not know if the lowers are further down or not. I guess that would also mess with the IC correct?

Just though of this too. If the car is lowered with springs will that push the IC further forward? These are the control arms http://umiperformance.com/catalog/index.php?main_page=product_info&cPath=8_60_74&products_id=94

I want to say, just quick visualization in my head says short top arm long bottom arm, lowering the car moves the IC rearward. The upper arm will move more degrees per inch raised due to the shorter arm, bringing the intersection point further back. I agree that you should do some measurements and see where you are at with IC.

Also, interesting setup, I'd like to see pics if you can find them.

 

[zildjian4life218]

http://www.hotrodders.com/forum/ford-8-8-truss-system-g-body-193547-6.html

Port 78 was an old design I had but same idea where the UCA mounts are. I am going to get the measurements and angles shortly.

 

[zildjian4life218]

Okay so I took some measurements.
LCA 0*
UCA 18* down
Pinion Angle 2-3* Up
Driveline Angle 3-4* down
Pinion Snubber distance 2 1/4"

This sort of confused me:
Drive Shock is 16 1/2" from top mount to center of bolt.
Pass Shock is 15 1/2" I do not know if this just play in the shock bushing or not?

**Edit** Also control arms are currently set to factory length.

 

[zildjian4life218]

Just to update I have some OEM springs I am going to put back in and also some competition engineering 3 way adjustable shocks to put in the rear. Just need to order some slicks and retest.