View Full Version : Need suggestions for intercooler pipe --> throttle body coupler

02-17-2012, 03:43 AM
Mine continues to blow off. I've used worm screw clamps, t-bolt clamps and nothing holds on :( It's blowing off on the throttle body side of the connection.

This last blowout scared the shit out of me. I was boosting about 15lbs in 3rd gear when it popped (felt like I went out of gear for a second). Pulled over, looked at it and this time I can't fix it. I just limped it home without boosting. I have a SIS 2.5-3" coupler. They say it's a 7ply silicon hose. I have the same product holding all of my intercooler pipes together, and none of these has blown off (yet).

02-17-2012, 04:26 AM
what throttle body inlet are you using? does it have a bead on it?

02-17-2012, 05:01 AM
Utah it's the stock one on the 215. It has one on it.

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02-17-2012, 05:22 AM
Then the coupler is too big so the clamp is fighting the coupler, the bead is not big enough (the bead on the ST215 is not designed to keep the pipe from slipping off as the intercooler is bolted to the cam cover), or you're not clamping it tight enough. On High boost race cars, the bead is easily a 1/4", and they put tabs on the piping so they can be braced together. Remember, there's alot of force on that joint. At 1BAR, if your pipe is 2.5" the force is about 69lbs, at 3"s then the force trying to blow the pipe off is about 98lbs. Without braces, the only thing holding that on is the friction of the silicone to the aluminum.

Here's one I found on the net, but most fabricators make their own.

vibrant intercooler piping brace (https://www.importfabrication.com/index.php?main_page=product_info&cPath=166&products_id=249)

02-17-2012, 04:56 PM
post a pic of your throttle body tim.

02-17-2012, 05:35 PM
I don't have one offhand, but it's similar to the turbo intake.

http://ourlewisfamily.net/gallery/../content/Jasmine/normal_wastegate.JPG (http://ourlewisfamily.net/gallery/../content/Jasmine/wastegate.JPG)

02-17-2012, 07:17 PM
so it's not a bolt on coupling like the other 3 generations?
a simple t-bolt clamp should work just fine there. are your pipes under a lot of tension?

02-17-2012, 10:57 PM
Found a picture of the ST215 TB.... (on the right)


With how narrow that throttle body inlet is... is there any chance that the T-bolt clamp is too wide, and the outside edge is clamping on the lip itself, therefore not clamping tight on the inside of the lip like it should be?

02-18-2012, 12:50 AM
Can you not tell when you tighten the clamp down? Do you need me to come tighten your hose clamp for you....

02-18-2012, 07:37 PM
Must not be clamping down hard enough if there's a bead. Maybe your coupler is too thick?

02-19-2012, 02:50 AM
a simple t-bolt clamp should work just fine there. are your pipes under a lot of tension?

This is my question. Unless you've greased it up, or the angle is just terrible and putting a lot of mechanical tension on top of the air pressure, the t-bolt should be holding it just fine (I fought this on the 7M set up because there was one connection that always got pushed down on by the sway bar, it was a low point collecting oil before it had a catch-can, and there was no bead on the pipe). Post a closer pic of your actual setup where it connects at the TB so we can give our best guess what you're running into.

02-19-2012, 09:59 PM
My guess is the coupler is a hair too big.

02-20-2012, 07:13 PM
Try spraying a tad of hairspray km. the connection point. Old mountain bike trick, helps it stick.

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02-21-2012, 06:32 PM
I think I figured it out. The vacuum line I ran for the boost gauge / BOV seems to be a bit too small, and it wasn't sealing properly on the inline filter to the boost gauge. Because of this when I would let off the throttle to shift, the BOV wasn't getting the vacuum quickly enough to release the pressure and it went for the next weak point (which I still should address with a new coupler or add a small bend to the piping to relieve any stress).

I pulled the filter out, put in a single line from the BOV -> T-fitting, relocated the filter just infront of the boost gauge sending unit and placed a larger line from the intake manifold to the T-fitting.

02-23-2012, 07:49 AM
The intake should be capable of handling an intake that doesnt even have a BOV...

You need to use a constant tension hose clamp... not a t-bar clamp.

T-bar clamps are notorious for not working right because they squeeze only on two sides of the pipe as opposed to around the whole circumference. There are lots of threads where people have used t-bar clamps and crushed their intercooler piping...

For you, i might suggest welding a vanjen clamp in to the TB and to your IC piping. I know a guy who is getting rid of one for cheap...

02-25-2012, 05:57 PM
Vanjens are nice but crazy expensive. Constant tension is a nice compromise, but tbolts really should be fine if you have decent quality pipe and a good bead.

02-28-2012, 03:35 AM
Vanjens are nice but crazy expensive. Constant tension is a nice compromise, but tbolts really should be fine if you have decent quality pipe and a good bead.

or you can use cheap IC piping, and cheap constant tension clamps... they arent that expensive...

02-28-2012, 03:49 AM

02-28-2012, 05:07 AM
Yeah... I'll go out here and say I disagree with AMS on this one... The problem isn't with the tension on a worm gear clamp, it's that the design of the band slots is such that it's the weakest point, and the screw drive will slide on the band not letting you reach proper tension.

I agree that a proper bead on the piping will do wonders for it not slipping off. HOWEVER... Silicone couplers and any type of clamp should not be used to handle the force of the pressure pushing the two pipes away from each other. They are designed to seal in pressure, not to keep the pipes from sliding apart. The pipe should be secured as such that even without the silicone there, the pipe will stay a constant gap from whatever you are connecting it to. This can be done with braces on the pipe to the engine/head whatever, or with the clamping system I showed above. Sure people have been using hoses and clamps with the piping free-floating... this doesn't mean it's the right way to do it.