legacycentral bbs

So I think I have decided to change the intake pipe upstream of the MAF to a piece of seamlessly bent ABS. I am assuming that getting rid of any place to cause turbulence will give me something. I am going to insulate it somehow as well. I have ideas ranging from a radiant wrap option (more legit-ish) to foam pipe insulation wrapped with aluminum foil and duct tape (super ghetto-ish). I think that I will wrap the air box too. It has to help.

The radiant wrap I am thinking about.
http://www.homedepot.com/Building-Mater ... reId=10051

Another question I have is whether taking out the snorkus and replacing it with a piece of pipe or something else will yield the same adverse results as removing it all together. I can't afford to loose any low end anything but I would like get any gains that I can.

I am looking for any hps that are hiding out in my car. Last event my evening runs were all with a fraction of a second of each other. Even a hand full of hps would help me out. That damn STI **Shakes fist toward the sky**!

Just found this too. I wonder if I wrapped everything in aluminum foil first if that would bring up the R value.

http://www.homedepot.com/Plumbing-Pipe- ... reId=10051

45 degree airbox mod would be good and it would be easier to do on a non turbo car I think. You could also bypass the throttle body coolant flow to remove some heat from the intake charge.
I like the idea you have of insulating the intake tract. It should help. Another thing to do would be to smooth the outside of the intake manifold. Less surface area to absorb the underhood heat. Much more involved though, or you could insulate the manifold which would help alot, but be a pain to do.

Jeff

If you are being cheap buy some emergency blankets from the camping store. They are essentially the same as the adhesive Mylar used for intercoolers.

jefferson wrote:45 degree airbox mod would be good and it would be easier to do on a non turbo car I think.
Jeff

Ok I'll bite. What the hell is a 45 degree airbox mod?

I am doing the tb bypass this weekend.

I didn't think about space blankets.

I would do a search and you will find pictures. The airbox is off an Impreza or later Legacy and the maf is angled in toward the engine. It will unshroud the entrance to the maf, get rid of a 90 degree bend, and it is also a larger airbox.

Jeff

Honestly....by modifying the intake piping at all from the air box to the TB, you will likely see a reduction in low end torque. Those polished aluminum intake tubes that were used years back on the 2.5 RS helped top end, but didn't necessarily help low end. The Cobb intake with the inline filter setup was about the only one that probably helped both.

Honestly....what I would do if I were you is do the tb coolant bypass mod, remove the snorkus from the fender and use mylar tape/wrap on the intake piping and airbox. If you want to go further, you could do the phenolic spacers between the intake manifold & heads. Beyond that, the amount of money/time/effort vs. potential gains is very lopsided.

I'd start with the TB coolant bypass & snorkus removal. Those things cost nothing. Drive the car after those mods, then do the heat wrap. You'll be able to determine whether the heat wrap actually did you any good. I have my doubts you'll see any measurable gains.

The only other thing I'd suggest is putting a velocity stack at the inlet of the filter box in the fender. Something like this. You'll have to see what diameter you need.

http://www.google.com/products/catalog? ... YQ8wIwAQ#p

You could also make your own velocity stack with the Volvo part I have written about and a heat gun. The hard part is finding the right Volvo in the pick and pull.

While you have the tb off to do the coolant bypass mod you might blend the leading edge of the tb to reduce turbulence.

Jeff

Taking out the accordion section of the intake tube would kill low end torque? Since I can't seem to find ABS pipe anywhere (back when I was making potato guns you could buy it anywhere) I was thinking of just wrapping the stock stuff. The heat wrap is for rallycross - I don't care about everyday so much. Running lap after lap at WOT with little airflow due to how technical the course is, the engine bay gets crazy hot. A lot of us will usually prop the hood up if we get any long breaks in our run group.

So taking out the snorkus won't mess with the MAF? I thought that it made it bog a low RPMs because it causes some weird thing to happen to the MAF. Was that just taking the airbox out all together?

Do you think that the velocity stack will help with flow? I was just going to throw a piece of pipe in there if I was able to change the snorkus without problems.

I never had any negative effect from removing the snorkus. I replaced mine with a hose attached to a NACA duct in the lower side bumper. The only time it would bog was when I rammed a snow bank and clogged the duct.

The velocity stack will help the flow. Long tubes don't flow as well as short ones. The Volvo tube is quite a bit bigger in diameter too.

Jeff

I think if I did the NACA duct I would clog my filter at RXs.

I will yank the snorkus tomorrow then.

coffeeman885 wrote:Taking out the accordion section of the intake tube would kill low end torque?

Are you talking about the entire stock black plastic piece with the accordian piece in it? If so, then yes it can. There can be pressure waves in the intake tubing, which depending on length, size, etc can affect how air flow goes through. You'll see on some of the newer cars that have the odd shaped plastic pieces off the stock intake tube. These are called helmholtz resonators. So modifying the intake can cause some negative effects, especially on non-turbo charged engines.

The link below has some more info on helmholtz resonators

http://blog.autospeed.com/2003/11/30/th ... o-intakes/


Also, regarding the velocity stack, as mentioned it can help improve air flow. They do this by allowing for a smoother transition of air flow into the airbox.

Legacy777 wrote:Honestly....by modifying the intake piping at all from the air box to the TB, you will likely see a reduction in low end torque. Those polished aluminum intake tubes that were used years back on the 2.5 RS helped top end, but didn't necessarily help low end. The Cobb intake with the inline filter setup was about the only one that probably helped both.

Honestly....what I would do if I were you is do the tb coolant bypass mod, remove the snorkus from the fender and use mylar tape/wrap on the intake piping and airbox. If you want to go further, you could do the phenolic spacers between the intake manifold & heads. Beyond that, the amount of money/time/effort vs. potential gains is very lopsided.

I'd start with the TB coolant bypass & snorkus removal. Those things cost nothing. Drive the car after those mods, then do the heat wrap. You'll be able to determine whether the heat wrap actually did you any good. I have my doubts you'll see any measurable gains.

The only other thing I'd suggest is putting a velocity stack at the inlet of the filter box in the fender. Something like this. You'll have to see what diameter you need.

http://www.google.com/products/catalog? ... YQ8wIwAQ#p

josh, the link at the end of this post will not work anymore i am interested in the volocity stack mod thing. if you could explain some more or hook me with another link so i know what it looks like thatd be awesome.

how would i attach the V stack? to the bottom of the airbox or attach to the fender well hole some how?

You'd have to use something to attach it to the intakae tube in the fender. You could try making a bracket, use tape, or whatever else you can find.