And it's the same differences of linear expansion rates that are responsible for our transmission pan gaskets leaking all the damn time, right? And the fact that the bolts fastening the plenum pan to the manifold are too long is irrelevant, too, I suppose?



Aluminum's coefficient of linear expansion is 12.3*10-6 inches per inch per degree Fahrenheit, while steel's is 7.3*10-6 inches per inch per degree Fahrenheit, which yields a difference of five microinches per inch per degree. So for a delta of 200 degrees, that's two-thousandths of an inch per inch. It's, what, four inches between plenum pan bolts, so .008" total relative motion per gasket segment? If that's going to cause gasket failure we're in trouble all over the vehicle and not just in the plenum pan.

 

I think the original gasket wasn't oil resistant. That was my feeling when I saw the pan the first time I replaced it.

 

The pan aint stainless steel, I can tell you that much. Its regular old steel. It seems kind of like false info to me to say "plenum is blown, no way around it". Not directing that at any one person, but I've seen it posted more than once. My 98 has 142k, uses no oil, does not ping, and runs pretty darn good. Plenum has not been touched, nor will it be until I see symptoms of failure. Will it blow? Probably, but not neceassarily before the transmission does (or head gasket, etc.). Seems like wasted effort to me to replace it because it will one day go bad, seeing how one day, if driven long enough, everything on the truck is going to fail at one time or another. I could be the only guy on here thinking that, but that's ok. Op said "engine revving doesn't correspond to acceleration", or something to that effect. Sounds like a transmission slipping to me. I'd hate to see somebody put effort into a top end repair, tuner, etc to find out they need a new transmission. That would constitute a bad day.

 

I think the rest of the vehicle has different torque specs than 15 ft/lbs like the plenum pan bolts.

 

It could be that your in overdrive, when in overdrive it will be sluggish but that is due to the gearing, you can turn it off when merging in and put it in once in traffic, with a tuner it will allow you to stay out of overdrive a bit longer which willl help

 

Yeah... the automatic transmission pan bolts are torqued to 13 foot-pounds.

 

Ah, so it is because the bolts were over-torqued from the factory!!!!

 

Yeah, yeah, that's the ticket! The gaskets get all squished up so when Marvin Martian fires the Pu-36 Exploding Space Modulator the warp in the space-time continuum is just enough to frobnosticate the vacuseelyum compound.

I think you're onto something there!

 

Huh?

 

No it won't. You will get more from the filter, than you will with the little doo-dad they are selling. All that thing does is feed the PCM WRONG information, so the PCM will richen the mixture. The claims of 20% horsepower gain AND improved fuel economy are bull.

I note that later they claim improved performance OR economy... If it were that easy to do, the factory would have done it. Nope. Snake oil. Many promises, delivers nothing. The 'butt dyno' isn't accurate enough to detect the change, if any, that would provide.