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3" intercooler pipe to big? with Holset Hy35??


big-phil

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I bought a holset hy35, and I've also got a 24x12x3 intercooler with 3" inlet & exit. would 3" mandrel bent tubing for the i/c plumbing be too big? I would use the 2 1/2 but I'm having trouble finding a silicone 90 deg 3" to 2 1/2" reducer for the intercooler. To make the intercooler fit I have to make a tight 90 bend at the in and out of the i/c I found a 3" silicone 90 bend for about $15 each, they want about $35 each for the reducer type.

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Phil, are you sure you want the bend to be made from silicone? It would seem logical to me that the joint would be stronger if it were made from whatever tube you were using, and then had a straight boot. How big is your throttle body? How big is your turbo outlet? I would think your boost response would be better if you only had one diameter of tube for as long as possible, so it might be better if you had your end tanks modified to the same size as your turbo outlet on the way in, and your throttle body on the way out? Anybody that wants to correct that, jump right in!

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the outlet on the hy35 is 3" OD and about 2.75" ID and my T/B is a 60mm Webber. Its 70mm at the opening, but then tapers to 60mm at the butterfly.

I could have the i/c modified, but the silicone 90's are alot cheaper. They are the 4 layer silicone with the webbing stuff inside.

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well, if it's already all 3", you wouldn't need to modify it anyway. In that case, I'd say going smaller than 3" would kind of be a waste of time. I guess I was confused about the real question, too. Are you asking if you should keep your old plumbing and use reducers, or upgrade to 3" plumbing?

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Guest 280ZForce

i used some 3"-2.5" 90* reducers...let me see if i can find the site. cheapest i found them was like $45 a piece though. oh yeah...welcome to the holset world! you will love it!

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well, if it's already all 3", you wouldn't need to modify it anyway. In that case, I'd say going smaller than 3" would kind of be a waste of time. I guess I was confused about the real question, too. Are you asking if you should keep your old plumbing and use reducers, or upgrade to 3" plumbing?

upgrade to 3" I got a new turbo, new i/c so I need new plumbing.

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yeah i bookmarked the site...just give them a call and place an order. mine have handled boost very nicely w/ no breaks or cracks so far, so good.

 

now to just get it tuned for some high boost.

 

4th one down...

http://www.boostcontroller.com/index.php?category=109&PHPSESSID=d17b5cf592bebac1982d05bb643588e3

thanks, $49 each, ouch! I need two of them.

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If your pipe is too large, it will take you longer to build boost, but if it's too small, you are just making a restriction. I'll see if I can't dig up from somewhere if there is a rule of thumb for tube sizing. My gut reaction is to keep it the same size as the compressor outlet at least to the intercooler, and then use your size changing adapter at the end tank, then use the same size coming out as your throttle body inlet. I think that's gone over in Maximum Boost, I'll have to check when I get home.

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Check in this thread for the calculations needed to determine proper size-

 

http://forums.hybridz.org/showthread.php?t=78488&highlight=intercooler

 

I ended up going with 2.25 and think its perfect for me. in the above post its mentioned that you should only run the larger size if your planning on making more than 500hp because it will have an effect on intercooler effeciency.

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Check in this thread for the calculations needed to determine proper size-

 

http://forums.hybridz.org/showthread.php?t=78488&highlight=intercooler

 

I ended up going with 2.25 and think its perfect for me. in the above post its mentioned that you should only run the larger size if your planning on making more than 500hp because it will have an effect on intercooler effeciency.

Thanks, thats a good read. I wont be at the 500hp mark, I'm hoping for at least 350hp. But everything on my car is about 3" from turbo to TB. So what the heck I guess I'll go with the 3" pipe?? How much hp at the crank is 350 whp? would crank hp be what you would use? or would it be fly wheel hp?

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would crank hp be what you would use? or would it be fly wheel hp?

 

 

Most people say "Crank HP" but, since the flywheel is dircetly bolted to the crank I guess you could use either term.

 

A general rule of thumb say you have 15% diveline loss. So multiply 350 by 15% and theres you #.

 

I've read as much as 25% is lost in the drivetrain but, I'm pretty conseravtive so I use the 15% number.

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