"The 2.6 right now is 3.0 undercover."

Maybe this is a question for it's own thread, but it seems this thread is already there.

Isn't a normal factory located MWE groove in a unaltered compressor housing designed to reduce the surging effects at lower rpms? It's goal is to widen the compressor map on the left hand side (lower airflow side), and it has no benefit on the right hand side? Most MWE grooves I have seen are behind the tips of the compressor wheel.

Therefore a comp housing with no MWE wheel should theoretically flow more air (however at the consequence of surging at lower rpms - not a big deal on a pulling truck).

Reading all the above posts leads me to believe some guys are running a stepped cover or a bushing "to meet the rules" and then adding a 0.25" MWE groove (or as big as rules allow) prior to the comp wheel which would allow more air to reach the compressor (not having to go thru the 2.6" bushing).

Just thinking outloud, but a MWE groove before the tip of the wheel serves a completely different purpose than a factory located unaltered MWE groove which I think is always behind the tip of the wheel.

Thoughts?
 
Good point if you have the .050 distance from wheel to bushing, that should take care of it.
 
The MWE's main intent is control surge.

However an added side benefit is that it does supply air at choke flow.

All factory MWE grooves I have ever seen are behind the tips. The original paper on the placement of the groove shows the means they used to determine where it is best placed. The point is to allow recirculation of flow, so it can't do that if it's in front of the wheel.

If it's in front of the tips, it's not a factory job and it's a competition workaround.
 
With a stepped cover, big inducer, or clipped wheel the MWE groove's purpose is far from what it would be with the factory wheel.
 
I assure the purpose of the MWE groove in this turbocharger is not to prevent/reduce surge. And it is located in front of the tip of the compressor wheel.

GT.jpg
 
Smokem said:
With a stepped cover, big inducer, or clipped wheel the MWE groove's purpose is far from what it would be with the factory wheel.
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That's where a restrictor plate/bushing would come in handy it wouldn't matter what you did to the turbo (or what turbo you run), it still only allows X amount of air (no need to buy new turbos, unless you are oversized as it is), maybe it's why people are so resistant.....
 
Smokem said:
I assure the purpose of the MWE groove in this turbocharger is not to prevent/reduce surge. And it is located in front of the tip of the compressor wheel.

GT.jpg
Click to expand...

I bet that flows TWICE as much as the center bore (plug test portion) would flow............No wonder guys are producing so much power with "small inducer bore" turbos.
 
Smokem said:
I assure the purpose of the MWE groove in this turbocharger is not to prevent/reduce surge. And it is located in front of the tip of the compressor wheel.

GT.jpg
Click to expand...

The wheel in this photo is on the witness protection program LOL
 
Leadfoot said:
I bet that flows TWICE as much as the center bore (plug test portion) would flow............No wonder guys are producing so much power with "small inducer bore" turbos.
Click to expand...

I don't think it's 2X, but it ain't chicken feed neither.
 
Matt your the math genius? If you take a 2.6 bore then add the area of a 1/4 opening before the wheel, as in the picture, what would that equal in bore size? I'll not call it a map grove, don't believe it serves that function at all.

Smokem said:
Same here.

BX.jpg
Click to expand...
 
highoutputc said:
i wish some of you ohio boys would come to newcenterville and show um how its done everyone thinks their a dam hero around here
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If your refering to me slap stick, we go pull with them guys when we can, i dont think a top 5 and a top 10 is to badwith a daily driver and a pos silver bullet, wait til next year bud when its not a dd!, those finishes are more than u did, what was that 16th? How bout your boss there, oh thats right he pulls 2.6 with 2.8 and dont leav somerset! Run your truck not your mouth! I know the ohio boys are top runners and i can respect them to the fullest, plan on runnin with them a bunch next year! Cya sunday slap stick!
 
mech2161 said:
Matt your the math genius? If you take a 2.6 bore then add the area of a 1/4 opening before the wheel, as in the picture, what would that equal in bore size? I'll not call it a map grove, don't believe it serves that function at all.
Click to expand...

I'm not Matt - and the flow doesn't completely work like your suggesting - but I do agree with your intentions. Adding a 1/4" groove in a 2.6" bore in front of the wheel as suggested increases the cross sectional area that air can pass through to something that is roughly equivelent to a 3.0 charger.
 
Just simpleassed math:

Area of 2.6 circle = 5.3 sq. in.

Area of .25" wide groove = 2.0 sq. in.

Area of 3" circle = 7.1 sq. in.

Just math....I'm not even gonna try and guesstimate the actual flow values.
 
And just for discussion purposes, rough numbers:

Garrett 88mm compressor @ 63.5mm inducer = 68 lb/min
Garrett 94mm compressor @ 67.8mm inducer = 80 lb/min
Garrett 94mm compressor @ 70.3mm inducer = 83 lb/min
Garrett 102mm compresor @ 74.7mm inducer = 95 lb/min
 
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