Cold side dia reducer

[Eddie Wilson]

I have a new PT3000 intercooler with 4 in in/outlets. My bonnet going on the intake is a 3.5 diameter. Where is the best place to reduce the daimeter of the cold side tube? Should I run all pipes 4 inch diameter and use a silicone 3.5 - 4 inch reducer where it attaches to the 3.5 bonnet?
Any help would be greatly appreciated.
Thanks
EWW

[Six_Shooter]

LOL, you have the opposite problem most people do.

I'd probably follow Corky Bells idea, only in reverse.

It is said that there should be a transition from one tube size to another at no more than a 15* taper. This will provide a smooth transition from one size to the next to help reduce turbulance in the intake charge. Remember, even though the air is under pressure it still has to flow well.

Depending on your installation you may or may not be able to accomplish this just before the TB, and it's only a rule of thumb, obviously not every installation is going to be able to adhere to this rule.

I would definatly try to use as smooth of a transition as possible, and using hard tube, not through a silicone coupler, that will induce much more turbulance, and even worse to do this at the alreay turbulant entry to the TB.

[Monty Mikho]

Make the transition as close to the intercooler as possible. A silicon transition is probably your best and cheapest bet. Make sure you add some supports to assist the hose clamps from blowing off the tube. Most everyone is using a rod end screwed into a piece of aluminum which attaches to a tab on the tube and on the intercooler..

[Eddie Wilson]

Monte,
What you are saying is, I only need to reduce at the 4 inch intercooler outlet? With a silicone reducer? And use 3.5 aluminum tubing from the reducer all the way to the intake?
Thanks
Eddie
"Another 2nd Gen with a big ass turbo"

[Monty Mikho]

Im sorry this is on the throttle body side? If so.. What I did was welded a piece of 4" tube onto my 90mm throttle body.. A piece of 4" 1/8 wall fit perfect.. Just need a small piece around 2" long I believe.. Then everything from there to the intercooler is 4".. From the turbo to the intercooler is all 4".. Sorry I was thinking your turbo and plumbing was all 3 1/2" already and you were already at the intercooler with the tube... You can also use a reducer but it looks a little nice increasing the side of the throttle body.. I hope this is what you mean.. Make sure to machine the clear coat off the throttle body before welding on it.. If im confused again please tell me.. I quit school in the 3rd grade and get confused easily.. :( If Im off please explain what a bonnet is.. Im confused..

[Eddie Wilson]

Monte,
A bonnet is one of those things that is sitting on top of Powski's Carb! Remember! Blow Thru's Don't Work!

[wheelie]

Sent you a PM.

[redvictor]

If Im off please explain what a bonnet is.. Im confused..
you call it a "hood"...lmfao

[Maliboost]

I thought that was the boot?

Dammit Andy, dont keep changing things on us.

bob

[Broke]

The rubber couplers from High Temp Silicones are real nice. The aluminum transitions have been a little pricey in the past but would be the best way to go. As a rule we run 4" as far as we can and then reduce down. Good luck.