TTopJohn

In this month's GMHTP, there is a dude who dropped a turbo buick engine in a CTS and is running 11.42@121 with it. They don't mention any rear suspension mods, so either
1) he doesn't have any and the stock suspension is perfectly capable of launching, it's just the rock hard run flat tires that are hampering the CTS-V, or
2)he does have suspension mods that let him launch the thing, and someone can get ahold of him or GMHTP, find out what they are and apply them to a CTS-V to cure the axle hop

http://www.gmhightechperformance.com...s/0405htp_cts/

BIGBOS

I've seen a video of that car running from back in the day when it ran 11.7's.......

People were shocked........

WECIV

Is the wheel hop caused by IRS???

TTopJohn

Well, not really "caused by" the IRS. But IRS cars certianly seem to be more suceptible to it.

i.e. I don't think Corvettes have a big problem with it, see the late night video clip of Dale Jr putting on a smoke show in a Z06 - no wheel hop there. But IRS Cobras have some issues with it, as do some Porshce 911s.

WECIV

ZO6's have IRS???

WECIV

Do you have that clip???

eswolfgang

iTrader: (1)

He does not have much more power than the CTSV by the numbers at the bottom of the article. I think I might try a second gear launch to see how it does.

TTopJohn

Yep, Corvettes have had IRS since 1963.

As for the link to Dale Jr on the Late Show, I can't find it on CBS's web page anymore. Check the Corvette Forum.

TriShield

The CTS-V has IRS, and the tune and some parts are different from the regular CTS.

WECIV

Thanks for the info!!!

alexWS6

http://www.cbs.com/latenight/latesho...ghlights.shtml
Its the 7th one down.

"Dale Earnhardt Jr. on 53rd Street
(2/17/04)"

TriShield

Buick power is hard to beat.

RogerH

IRS cars tend to wheel hop alot more because there is alot more deflection under load. Wherever there's a joint there is a loss of rigidity (i.e. where the control arms bolt to the differential housing or subframe or whatever). A live axle car only has to mount the axle and shocks, maybe a few suspension links to the chassis of the car. The IRS car has the rear suspension subframe, control arms, shocks, the differential, spindles, you get the point. That is alot of deflection underload. The suspension angles can get pretty odd under load. If the suspension is designed correctly, the parts can "lean on each other" for lack of a better term, and support one another increasing the rigidity of the unit significantly. Bracing is another way that manufacturers increase the rigidity of an IRS subframe. From what I understand one of the more serious issues with the earlier Mustang Cobra swas the entire assembly was to flexable and it was leading to problems with undesirable suspension geometry which caused the wheelhop that made such a bad first impression on everyone. Ford beefed up the subframe on the design and it made a remarkable difference in the reduction of wheelhop. Stiffer bushings will make a big difference to, but they will lead to a harsher ride, and more road noise transmitted into the car. Hope this helps shed some light onto the subject.

Roger Hewson

RogerH

The turbo car might have more torque at lower rpm when you load it up aginst the larger load making it easier to pull the longer gear. Regardless second gear transmits less torque then 1st gear does so this may not be a bad idea. If you can pull the lower speed ranges without boging the motor I'd go for it. Plus, you'll gain time for not having to shift into 2nd gear.

Roger

WECIV

Thanks for the vid!!! Man, was he hitting the limiter or what??? I hope that was his car, & did not get sold to someone, LOL.

WECIV

Kind of a small place to be doing that, I think I would want a big parking lot, however; I just would not do that to my baby!!!

Tudds

iTrader: (4)

that vid was ******* great