bfurches

iTrader: (12)

I know this is pretty far off from the typical discussion in this section and not something most of you play with....however I also know that there are some really talented suspension guys in here that will have some valuable insight regardless of what wheels I am driving.

Some of you guys have probably seen my car on here or Facebook. We just finished building the entire package in 3 weeks. The car is a 2005 Monte Carlo SS with a LS4 Conversion.




Current combination consists of the following...
-2005 LS4 with fresh rings/ bearings (stock rotating assembly)
-Stock 243 heads with BTR Springs/ pushrods & EPS Camshaft
-LS2 Intake with a FAST 92mm Tthrottle body
-Bullseye S475-83 1.0a/r V-Band exhaust (cast wheel standard cover)
-Single Turbosmart Hyper-Gate45 and Raceport 50mm
-2" Hotside merges into 2.5" which steps up to 3" at the bellows and into the turbine housing.
-3" cold side with 22x12x4.5 intercooler core
-Stock 2002 Oldsmobile Aurora 4T80e Transaxle (3.71 FDR)
-Stock Olds Converter (10.5" stalls about 2500 rpm behind the LS4)

The car has a race weight of 3710 and is run on E85. Right now it is at about 18psi, but was running out of fuel on the single pump (just addded another to the bucket so I can turn it up).

First time out with the car at the track last Friday on bone stock suspension and very old slicks we went 11.0 @ 133.8 running out of fuel. Ran out of time to make the additional changes I wanted and went up on bone stock suspension.



As you can see....even with the slicks the 60' was horrible. (granted the tires are old...but still...) If you look at this photo sequence...you can see that the front lifts like a rocket and hits the rear tires hard. This is leaving off the foot-brake at 5psi with the two-step set at 2300rpm.





Here is some video to go with the photos above...


So based on what you see above, what are your thoughts and suggestions? I am thinking limiters in the front would be a really good place to start. I have also thought about adding some time of blockers in the rear to keep the suspension from compressing...but I dont know if something more progressive like an air-bag would be better.

Also in these runs, I had no front sway-bar on the car. Would it help or hinder the performance if I added the bar back on? (think IRS cars....what are you corvette and late model camaro guys doing? since the FWD basically is IRS)

Any and all input would be appreciated from some of the gurus.

JL ws-6

iTrader: (50)

Going to have to stiffen whole car up to stop weight transfer....

Bitemark46

I'd start at the rear. Since the inertia of the car wanting to suddenly go forward it wants to lift the nose and move the weight towards the rear, I would get stiffer rear springs and stiffen up the shocks on compression. Maybe even raise the ride height in the rear to move more weight forward (or lower the front either way).

For the front I'd stiffen up the struts on extension.

I didn't see it but whats the tire pressure at? When I've been in the staging lanes I've seen a few FWD cars on slicks and they damn near had the tires almost flat. Really low tire pressure. Might be something to look into.

-Mark

JL ws-6

iTrader: (50)

I know a couple fools that rice imports that actually take the rear shocks out at the track and bolt a solid tie-rod in the shocks place, locking the rear suspension in place preventing any weight transfer at all. The fronts they have travel limiters on so that the car can not raise up at all.

A set of limiters to stop the nose from lifting at all would probably do wonders for you, as stated above the tires just about flat, and the rear anything you can to do stiffen the ever living hell out of it will help.

JL ws-6

iTrader: (50)

On another note Bitemark that's an awesome quote in your sig LOL, I haven't seen anything that retarded posted in a long time.

murphinator

iTrader: (2)

before owning ls1 cars I had several w bodies that I raced regularly (gtp's & regal gs's)

unlike your build mine were very grassroots budget efforts where I had a grand or 2 in mods ( best of 12.1@118)

the above advice is spot on in stopping rear end squat I did it in the most ghetto way but its very common on 3800 forums called the "cable mod" where you jack the rear of the car up off the ground letting the suspension completely hang down and 3/16 stainless cable with u bolts locking it in the fully extended position , jacked way up in the rear keeping all possible weight on the front tires , you feel every pebble on the tar , its harsh but effective. There has been concern of what if a cable broke at speed dumping a rear corner at speed so I also ran "gto spring blockers" in the rear springs which locks 3 coils extended , they were used in shipping rebadged holden cars from Australia.



the cable mod pic was just a mockup I did to show someone how it is basically done on another forum done on a crusty car I was parting out , it was a buick so you could go around one of the mounts for the k member as buicks used rubber isolators , gtps were metal to metal so I would go around sway bar mount instead . With your budget obviously being higher on this build look into some type of extended solid bar to replace the rear struts- look into zzp's w body record car I believe it used coilovers jacked up in the rear , car went 8.6 @159 on a 1.4 60 so its possible , car was also on stock shortblock/rotating assembly with just a cam/chain slid in it 3800 turbo setup...

I tried limiting front extension with cables before finding out people were jacking/locking the rear , rear is where its at.

I have been as low as 13 psi on dr's as well and had only 225/60/16 dr's trying to hook up on cold street nights ( only went with very negative da's) I only got 1.9 60's but on your tire I am sure I could have dead hooked but didn't want that to happen built 4t65's arent cheap and I wasn't looking to break.

I also slid pass seat full forward and drivers seat as far forward as I could still effectively operate the car at.

on street tires that car will go up in a ball at 90mph wont it ? lol

you may get a bit more weight over the front with top engine mounts like the gtp/gs had with shorter dogbones to pull the weight of the engine slightly forward or fab your own heim joint limiter , I used to use a ratchet strap but again I see your budget and skill level are a step above that...

Bitemark46

LOL. Thanks. When he posted it I about fell out of my chair laughing. Same guy thinks that his 417rwhp n/a LS6 6 speed camaro went 1.2X 60' on DR's.

I'm not brand loyal but I am stupidity biased.

-Mark

JL ws-6

iTrader: (50)

Lol yeah sure it did. He forgot to tell you it was a 1.612 lol. That kind of stuff cracks me up, but the bad part is there's people that actually believe that kind of crap.


When I noticed it yesterday I almost spit out my coffee. That's one of the dumbest things I think I've read in a while, anyone that actually thinks that has obviously spent zero time racing, or even hanging around a drag strip.

Pro Stock John

iTrader: (34)

If you can get them in, air bags would be something cheap to try. Adjustable shocks too.

bfurches

iTrader: (12)

Thanks for all the information guys. Basically validates my thoughts.

I know the rear suspension is very important...but I HATE the idea of locking the suspension from traveling at all. I feel that at 140mph if the car were to get loose or hit a bumpy shut-down things could get bad really quick.

I was browsing different OEM replacement spring rates last night, and I found that front F-Body LS1 car springs from moog have a constant rate of 290lbs-inch and a load rating of 1436lbs vs the stock rear coils which are variable at 88lbs-inch and only have a load rating of 467 lbs. So naturally my thought is to use the front F-Body springs in my rear struts to stiffen up the suspension.

For the front, I think I am going to start by strapping the car down 1" or so, and adding some chain limiters so the nose can't rise from the factory sway-bar hole up to the strut mount.

Heading back up on Friday.... we'll see what happens.

murphinator

iTrader: (2)

I think technically by nhra rules there is supposed to be something like 1" of travel so maybe some type of limiter/bump stop that is right on the rule book?

Consider this... your past (as well as mine before buying my first w body) is rwd where like you say if you get loose at speed it can get real ugly. w bodies have virtually no torque steer if they spin they continue to go straight.

w bodies are hard to get out of the hole but after that they are pretty simple the front subframe is beefy and holds the entire drivetrain , the rest of the car is simply trailing behind

Probably the biggest strength to modding one is once you get a trans and axles that will hold the power theres really not much required , the body doesn't get torqued , you have way less parasitic losses ( reason oem's make so many fwd cars= packaging and efficiency) no driveshaft , u joints , rear end to turn , way fewer suspension components needed to make it go down the track properly, stop wheel hop etc... add up the cost for the typical f body rear end ,transmission , driveshaft , u joints ,ds loops , suspension , etc.. to go 9's that is a lot of $$ to spend on making more power to go fast on the top half of the track with a w body.

Its not for everybody and good luck selling one modded that heavily afterwards, the buyers market is very limited your pretty much going to have to part out to recoup a decent amount of your investment.

I am excited to see you take a crack at it , from watching your past projects this thing is going to scream once you get dialed in to it

oh yeah you need skinnies for the rear too , everything is backwards lol