TRD clutch

[industrial]

Originally Posted by Jeff86

Your clutch is in between shifts and your boost is dropping. The flywheel has everything to do with how much you lose. Enough inertia at the flywheel combined with a quick enough shift and you're boost and power is still right there to kick you in your immediate ass. Further, evidence does support that the load from the fkywheel, perhaps due to the direct connection to the crank shaft, does influence the buliding of torque, This has nothing to do with turbo lag and nothing to do with "vrooms". I've been making good power building forced induction cars for years and just trying to convey experience. Take it or leave it.

Been driving and wrenching turbo cars for a while myself and I disagree with your statements and the general anti-flywheel for boosted cars mantra here. I'm not sure where that started.

Once the engine is up to speed...it's up to speed. If you want to build boost pressure fast after shifting, use a no-lift shift program. If you want to build boost between shifts, that's anti-lag. A heavy flywheel does jack all compared to those two things.

Do you have some data to back up what you're saying?

I'm saying is a light flywheel speeds up the acceleration and deceleration of the engine. Any boost you gain from pre-loading the engine another 10 pounds in the fraction of a second it takes for you to shift is peanuts in the grand scheme of things. A heavy flywheel to help build boost doesn't make any sense to me. If you want to be able to launch more consistently a heavy flywheel will probably help. No nearly as much as launch control though. If our car was heavy and needed the extra weight of a heavy flywheel to accelerate sharply from a stop you might have a point. That's simply not the case here. There is no reason for a heavy flywheel other than drive-ability reasons. Taking off smoothly, controlling revs, shifting smoothly, etc.

Once you start turning and braking, shaving 10 pounds of rotating weight off the front of the car as well as being able to manipulate the engine faster is just full of win.

[Jeff86]

Originally Posted by industrial

Been driving and wrenching turbo cars for a while myself and I disagree with your statements and the general anti-flywheel for boosted cars mantra here. I'm not sure where that started.

Once the engine is up to speed...it's up to speed. If you want to build boost pressure fast after shifting, use a no-lift shift program. If you want to build boost between shifts, that's anti-lag. A heavy flywheel does jack all compared to those two things.

Do you have some data to back up what you're saying?

I'm saying is a light flywheel speeds up the acceleration and deceleration of the engine. Any boost you gain from pre-loading the engine another 10 pounds in the fraction of a second it takes for you to shift is peanuts in the grand scheme of things. A heavy flywheel to help build boost doesn't make any sense to me. If you want to be able to launch more consistently a heavy flywheel will probably help. No nearly as much as launch control though. If our car was heavy and needed the extra weight of a heavy flywheel to accelerate sharply from a stop you might have a point. That's simply not the case here. There is no reason for a heavy flywheel other than drive-ability reasons. Taking off smoothly, controlling revs, shifting smoothly, etc.

Once you start turning and braking, shaving 10 pounds of rotating weight off the front of the car as well as being able to manipulate the engine faster is just full of win.

Well I know we've gone off topic here, but I decided to do some checking. Like I said I don't want to be a know-it-all and frankly, this is something I've just done without questioning for a number of years. I went back to my old forums where we were all pushing builds well past 400whp. The general consensus at the time was to resurface or replace the stock flywheel when we installed clutches that would hold the power. The reasons for retaining the stock weight were everything I indicated above... and the 10 second car guys were all doing it hehe.

So did i come up with any proof? Unfortunately no. I do still believe what I'm saying regarding maintaining boost based on those discussions, though. In addition, streetability was coming into play with the firmer clutch and the stock flywheels just worked better. I'd say that at lower power levels (below 300whp) it's probably far less important. Still, I'm getting more serious about going to a small turbo on this car and if I do that the stock flywheel is staying in there. It would be tough to convince me that rapidly dropping RPMs was good for boost. Lets just agree to disagree on that point.

[industrial]

Well, you'll see drag guys also keep heavy flywheels because they are usually running slicks. The more traction you have under your car, the more energy you have to store in the flywheel to get some wheel spin on launch. Might seem silly to even think about but with drag slicks on this car stock, you'll probably bog off the line unless you did a 7000 rpm dump with a 4 puck clutch and a 30 pound flywheel. For drag guys, it's that balance they are looking for too. The bog caused by too much traction and too little stored mass in the flywheel for drag guys is probably where the whole "lightweight flywheel sux for turbo" started.