Breathing 101

[Bimati]

With the new lift, wheels and tires, running from 0-75mph is like waiting for a rocking horse to drop turds.

On a slim budget, I am wondering how to get better flow/breathing and what I can expect for performance/mileage improvement.

I have ordered the kit to ditch the airbox and replace it with a K&N cone filter, and I would like to get a new muffler...(Morgan-Tec?)

That frees up the eater and the pooper...what can I expect from the changes?

Moronic question of the day: Ya know how some customs shorten the exhaust make it exit to the side in front of the rear wheel well? Why can't I just put a little downward stub tip out of the muffler and eliminate the tailpipe altogether?

Please be gentle.

Bim

[Tone]

Ain't gonna happen - it isn't your intake or your exhaust it is your gearing. The ONLY way to change the lugging on the highway is with an expensive dif gear swap or go to back to smaller tires.

A SC will get you back to where you were plus a little but that will not overcome the additional weight or wind and tire resistance.

[Bimati]

Right, then.

Let me clarify: Even when cruising on the interstate, she seems to be working/breathing hard, and I don't want to change the gearing.

What performance/economy changes if any can I expect from removing the airbox, installing the K&N cone filter and getting a free flowing muffler?

And if anyone can answer my stub tip question above, I would appreciate it.

Bim

[Joe_Black]

Tone's right on: The bigger diameter tires is your problem. Had the same thing happen when I went to 31X10.50's on my '88 Trooper. Get an extra set of wheels with stock diameter tires for your daily driving and use the big meat for show-n-tell. Otherwise you're going to start getting "Thank you!" notes from your local gas stations.

[zilik]

The engine is basicaly an airpump. The better you can make it pump by improving intake and exhaust will help it pump more at the higher rpms where the stock restrictions really show. At highway cruising speeds you won't see a lot of improvement. Gas milage may increase ever so slightly but not much. Gearing could help but at the cost of gas milage. A blower is the cheapest most effective way to increase low end HP because it force feeds the engine. The blower also won't effect highway gas milage, just around town milage cause you can't keep you foot out of it because it's so fun. This is the price you pay for big wheels and tires as it takes Horse Power to move that stuff down the road. Bummer huh!

I live in the mountains of Colorado and my biggist complaint with the VX is it's automatic transmition. The first auto I have ever owned in my 33 years of driving. When going uphill the transmition shifts constantly trying to maintain speed. Of course the power button helps and one of those intercepters that Tone sells would help too!. The intercepter may help you too!. Of course I want a blower and the intercepter but if I did that my wife would want the same on her's too!. She says no, but once she drove a blowered powered VX I think her mind would change. I know she loves the hill climing power of our 944 turbo.

[Bimati]

Thanks for the input guys.

Let me Re-clarify:

Forget about the wheels and tires. I KNOW the reasons my VX is acting the way she is.

I simply want to know about the intake and exhaust changes and if there is a reason one can't stub a tip behind the muffler eliminating the tailpipe altogether.

Zilik: I'm CO too.

Bim

[Joe_Black]

Sure, you can change the exhaust as much as you can stand from the standpoint of noise and federal compliance. If you want a side exit ahead of the rear wheel you'll be before the muffler somewhat, so will likely need to drop altoghether or use a flatter oval-section muffler like a Flowmaster. If you go that route, be sure to incorporate some type of heat shield to keep from melting your carpet.

As for the intake, something like a good cone filter or the Morgan-Tec intake will allow less restriction granting a mild power increase. But any increase in power from more air intake means proportionately greater fuel consumption, especially in the case of forced induction from a supercharger or turbo.

The surest way to get more power and economy is to replace your engine with the direct-injected version of the 3.5 from an '04 Axiom or Rodeo.

[JHarris1385]

Looks like you are finding the answers easily. If i knew i would tell you. Iv had the same problem when i start threads. THey go off the subject or focus on something other than the main subject and the answers are never found.

[kpaske]

JHarris -

Continue to read, and most of the answers you seek will be here. Do a lot of searches. Many of the veteran members here have answered the same questions so many times over the years they may not be so quick to respond anymore because the info is out there. We (especially me ) tend to go off topic a lot, but not too many people seem to mind (except the thread starter, of course, if s/he doesn't get the question answered).

Bimati, et al -

What about regearing the diffs? I know the parts are nearly impossible to find right now, but I've been toying for a long time with the idea of having some 4.77 or 4.88 gears fabbed up. Wouldn't the higher gear ratio compensate for larger tires and improve fuel economy?

Joe -

Don't forget the DIESEL swap option!

[tbigity]

Looks like you are finding the answers easily. If i knew i would tell you. Iv had the same problem when i start threads. THey go off the subject or focus on something other than the main subject and the answers are never found.

you mean like you just did?

not to be an ace or anything...

[Triathlete]

Another bad thing about exiting your exhaust in front of your wheels is that the exhaust fumes can find their way into your vehicle...not a good thing.