Author Topic: Blow through turbo setup- plenum/carby hat design and inlets  (Read 6076 times)

orangeLJ

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Blow through turbo setup- plenum/carby hat design and inlets
« on: September 28, 2011, 11:21:46 PM »
Well I figured I would throw this out there as quite a few people on here play with forced induction.

Im building a cheap (yup, cheap) twin turbo setup to have a bit of fun with my HX ute.

Its running a 253ci V8 (holden) with a tiny camshaft (not much over standard) and standard internals/comrpession (like 8:1 - 8.5:1 maximum)


Ive picked up two similar spec ex-WRX turbos (TD04Ls, internally gated) with similar kms etc.

Ive also grabbed a 4 barrell inlet manifold with Holley adapter and a 650 spreadbore Holley.

Im only planning on 6-8psi max, nothing overly massive.


My dilema is this-

Is there a general rule of thumb in terms of inlet pipe work from the turbo to the carby hat?

The TD04Ls have a 2 outlet (well, 54mm)

Im currently making up a carby hat to suit the 650, but Im worried about making the inlet pipes too small.

The carby hat will be a basic 90 degree design with a slight bulge similar to this-



Except obviously with two inlet pipes.

So what size should the inlet pipes be? Is there a rule of thumb when it comes to matching the inlet surface area with the surface area of the carby butterflies?

Im worried about excessive pressure drop from going too large as I want this spooled as early as possible (its not a big revving engine, so dont ant to rev the tits off it)

Would 2.25 do? Or should I go for 2.5?

Any help would be good!

Cheers,
Chris



orangeLJ

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Re: Blow through turbo setup- plenum/carby hat design and inlets
« Reply #1 on: October 04, 2011, 10:34:33 PM »
nobody?

FoMoGo

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Re: Blow through turbo setup- plenum/carby hat design and inlets
« Reply #2 on: October 04, 2011, 11:08:36 PM »
OK Sounds like you are going non intercooled.
No worries on pressure drop, you get that from restriction between the turbos and the engine.
You will be getting the flow no matter the size of your pipes, your carb, intake, heads... will be more of a restriction than your tubing.
Are you running petrol, LP, alcohol?
Are you set up to pressurize your fuel bowls and fuel pressure regulator?


Jim
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orangeLJ

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Re: Blow through turbo setup- plenum/carby hat design and inlets
« Reply #3 on: October 05, 2011, 05:54:27 AM »
petrol (unleaded petrol) non intercooled.

Carby etc is all sorted (boost referenced holley)

So twin 2.5" pipe would be fine?

The carby "opening" is 5" and the butterflies work out to be  9.34" squared (surface area)

The twin 2.5" inlets end up with a surface area of 9.8" squared. where as the 2.25" inlets end up at 7.94" squared.

so 2.5" inlets would more than likely be the best option?



FoMoGo

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Re: Blow through turbo setup- plenum/carby hat design and inlets
« Reply #4 on: October 05, 2011, 08:57:37 PM »
2.5" will work fine.
You MAY want to look at methanol injection... especially if running cast pistons.


Jim
http://www.turbopinto.com/images/ar/asshole.jpg
Old avatar: http://www.turbopinto.com/images/ar/jimsmall.jpg
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Quote
Moral of this lesson:
Don't get in any gun fights with buffalo hunters. There ain't no such thing as cover.