Only thru the traps...................

 

This makes a lot of sense. GM wouldn't provide a relatively cheap power upgrade if they thought it would create significant tranny warranty problems.

Give it a buffer of 10% just to make sure (290 x.10 = 29hp) and 320 seems like a logical upper limit.

On the other hand, the General isn't well known for an abundance of logic!

 

GM's drivetrains are some of the best and most reliable around. GM has always had standards on how much the transmission had to be able to handle over the stock power. That is why seldom you see a GM transmission break under normal use. That is also my for many years companies like BMW, Jag and Rolls have also used GM trannys. Even Ford went to GM to to the joint 6 Speed transaxle both use today.

In the last 15 years they are cutting things a little closer than they have in the past but the electronics work to make the transmisison live. Often engines will kill torque for a fraction of a second at shift points to make it smoother and make it no have impact on the transmission. This is why the new 6 speeds are so smooth you have a hard time knowing what gear you are in.

The HHR tranny came out when power was not expected to go this far with V6 and 4 cylinder engines. GM was short money so they 6 Speed came late till FOrd offered to share the cost. Alas it came too late for the HHR since it will not fit. But it will be in all new cars as the HHR and Cobalt I think will be the last 4 speed auto made at GM.

Either way we have a little room since GM will cover the warranty on the Upgrade kit. But I would not push it since they killed the HP from the RWD. They did it for a reason.

 

yeah, the rwd will hook up much better because of weight transfer and whats that shock going to do to the trans.....the fwd cars unload a bit because of weight transfer thus easier wheel spin.....
Somewhere somebody is going to have to bite the bullit and see just how much this thing can take, so the rest of us know where to stop building.

 

Just read the Cobalt and GTP web sites they have found the limits. I learned from their broken parts.

It is kind of like the guy in high school that said his Camaro with a solid lifter cam could do 7500 RPM. Well it did about a dozen times and then he had to get a new block.

I saw a guy in a GTP with around a claimed 340HP leave the diff on the track at Norwalk. He did it right on the line with slicks. Cars with out slicks can take more since they don't get the intitial drive line shock.

I learned long ago from the Fiero guys the diff and the axles are the weak link. The tranny itself is no Turbo 400 but it will do a lot getter than many think. Now if you beef the axles you may lose the geat in the tranny.

FWD is not better traction as the lie has been since 1980. It is easier to use in slippery conditions for people with poor car control.

When Pro Stock and Top Fuel go FWD I will buy it is better traction. It is simple physics For ever reaction there is a equil and opposite reaction. That tells you the weight is going to the tail and on the non drive wheels.

 

Yup. You need a fuse somewhere in the drive train otherwise the trans/differential or axles become the fuse. Back in the day of running VW engines with SPG roller bearing cranks we quickly discovered that we would twist cranks if we ran too sticky of a tire. We had to learn to manage the traction or risk wiping out a $200 crank (in 1971 $). That meant finding tires that were right for the job.

I would imagine the 4T45E can take a lot of input shaft torque but you need something cheap to "give" and that is best left to the tires. No doubt it could be built up to handle more but you need to talk with someone that has actually found the limit.

Take Hyper's advice and read up on the Cobalt (and Cavalier) forums and see what they have discovered with the 4T45E. When my son had a Cav Z24 auto I did some reading and they were resorting to better clutch packs, etc. but I don't recall the limits they found on the stock tranny.

But I would assume you want the trans to work more than once "down the track". ...

 

I think the tranny limits is 475, but I'm sure you can build it to take that and more... I think a bigger problem would be wheel hop trashing the tranny and throwing shafts.

Sandmanse, Skip the Intake and do the exhaust and I/C piping. contrary to popular belief we have a fairly decent CAI already, that I think is the reason no one has designed an effective CAI that doesn't consistently throw codes.

 

well my tranny out lasted my motor twice

 

475? That is alot more then everybody else is claiming it can hold, what makes you say that?

 

This is based on some old threads, i keep trying to find, it was around two years ago before the turbo upgrade became available. some thread members were looking into the specs and I thought that was the number that came up as "stock limit" for the tranny, not anythig else