Turbo Exhaust Housing Porting question

[HEMI®Dart]

I was going to gasket match the exhaust manifold outlet to the turbo exhaust housing inlet ports.
Look at the pictures below.
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See the 2 recessed areas just above the flange where the turbo bolts to the exhaust manifold? (right side picture better)

Inside the housing are 4 raised bosses (2 per side) on the bottom & top corners of the ports. The opposite of what we see on the outside.

It looks like if I can grind these down (the raised bosses on the inside of the housing) I could really be able to make this thing flow. I`m guessing at minimum 10% better flow. Probably more. These raised bosses are pretty good sized. Maybe an 1/8" tall or better.

Are these cast into the housing to make it more rigid?

And do you think I`d break thru #ad
if I ground & polished the bosses flush with the ports? I looks VERY possible.

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Bill R
94 2500 SLT 4x4 5 Speed, 3. 54 LS, JRE 4" exhaust, Autometer Pyro, Boost & Water temp gauges, Bosch 215 HP injectors, Timing @ 14. 7 º, JRE Stage III #4 plate 270/675, AFC spring kit, Scotty Air, Bully Dog Propane Injection, Roadmaster Active Suspension, Optima Red Tops, Geno`s Exhaust Blanket,Espar Heater (won it!), Synthetic lubes throughout.



[This message has been edited by HEMI®Dart (edited 12-16-2000). ]

 

[drawson]

Hemi, I did just what you are talking about to my 16 CM2 housing. I didn't get a complete gasket match, but I know it should flow better. I also did the manifold while on the engine just before putting the housing on. It really looked as if the hold exhaust side could use the extrution hone done to it.
I opened up and smoothed out the down connector also.

These little things are what kept my race car just a head of the other cars.

I have also ported my intake tube when I first put in my torque plate. I plan on porting a used head and putting it on maybe as soon as next summer.

Go for it just be patient and go slowly.

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EAT'M UP
97 2500 Club 4X4 3. 54, Forrest Green/Driftwood, LSD 5 speed, & Psychotty Air System, TST #11, 370 HP injectors, timing at 16 deg. , 16CM2 housing, AFC spring kit, Geno's Exhaust Blanket, TST EGT gauge & 0-60 boost gauge in A Pillar, Cat-be-gone, 4" Dynomax Bullet muffler, Crome 4" turn down, AmsOil Through out, Geno's trans filter kit, AmsOil Bypass system, Lund Winter front, Leer Cab Level Shell Driftwood , 255/85R16, Dyno'd 342 HP pre injectors & turbo housing *NRA/USPSA member and proud of it*

 

[Rebel]

HEMI®Dart, I've been wanting to do something to improve the flowrate of the 12cm2 housing myself. To me the recessed area's look like they were cast in to the housing to provide room for the fasteners. It would be nice if their was a junk housing laying around someplace so as to determine the wall thickness in that area?

All that said, the area of maximum restriction is where the exhaust gasses flow through or around the turbine itself.
At any rate it would be interesting to see what the modificatons you propose would do for performance. Bomb that baby! #ad


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1997 2500 Ext Cab 4X4,5 spd,3. 54's,Pac brake,Rancho 9000's,Centerforce clutch,K&N airfilter,Missing Cat,Isspro gauges,and #11plate(280hp/680tq)AFC medium spring

 

[HEMI®Dart]

Back to the top

If anyone has gasket matched the turbo exhaust housing, Did you have any trouble breaking thru the recessed areas.

 

[Joseph Donnelly]

Mark Chapple of TST worked for Cummins 33 years, of which 12 years was turbo development. He said every couple years a new crop of engineers was hired and someone spent 1-3 days porting the exhaust housing, gaining zero on the dyno. If you want more flow, port the head, intake and exhuast, especially under the valves (so called pocket porting), carefully! Get the ATS exhaust manifold and port the inlets just to round them off to port size, not so big as gasket size, please. That manifold so modified will increase flow about 15%. The head work will increase flow something like 25% if I recall the numbers from Piers. These ods will give ZERO horsepower, but will lower egt so you can safely add more fuel, which will give more hp.

 

[My 6 Eats V8's Old File]

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well said JD #ad

 

[NVR FNSH]

Mark's Cummins experience is on par with what I was told when I was at Garrett. Remember, the turbine & compressor housings are cast - can you say variability? Porting just the inlet of the turbine housing isn't going to give you a whole lot of improvement.

Story from Garrett:
We had finally received several new turbine housings and couldn't wait to get them tested - We were expecting big improvements from these new split volutes. Got them tested and couldn't figure out why the data was so bad... . Re-tested & re-tested (multiple housings of each PN) thinking it was the test stand. WRONG. Finally, we sectioned 1 each of the housings and found the problem. The cross-sections were way off from design - the cores had shifted. One side of the volute was ~25% smaller at each given cross-section.

My point? Manufacturing variability will play a big part in the turbo flow numbers and there isn't a real feasible way to blue print the housings.

Brian

 

[John]

... . that's why I used an old machining trick... the use of Prussian bluing to print the turbine casting inlet ports to the two ATS manifold outlet ports. #ad