Porting Stock Elbow

[Getchasum]

I know that there was some info posted in the tech section on the gains of porting a stock elbow. For some reason I can not find it. (1) Can any one give me the expected gains for porting a elbow and adding the lager puck? (2) After porting stock elbow would there be any additional gains in the Poston 3'' down pipe? Or does must of performance gains come from elbow? Tks Scott

 

[SPOOLED UP]

I've never had my elbow off, but what is the best way to open up the hole where the puck is?

 

[UNGN]

Like steve said, radius the edges of the hole. Sometimes, just putting a good radius on the inside of the hole allows additional flow and you can cure boost creep and not significantly open the hole up.

Drawbacks to opening the hole up to a larger diameter are you will have to adjust your wastegate rod tighter to achieve the same boost setting. Which means now its harder to adjust the rod and the max boost you can run has now been reduced.

A big mistake a lot of people make is they get a new elbow with a larger puck, then open the hole in the turbine housing to just under puck size, and now the rod has to shortened 1/4 inch to achieve the same boost. If they didn't have a creep problem to begin with, they solved nothing and made life harder for themselves in one easy step.

A dremel tool with a double cut carbide burr will cut through cast iron like butter. They cost more and they are harder to find (Lowes, Home Depot and Walmart don't have them) but they will last forever (relatively...20-30 hours of cutting cast iron) I usually bend them before they get dull.

 

[UNGN]

Originally posted by Getchasum
I know that there was some info posted in the tech section on the gains of porting a stock elbow. For some reason I can not find it. (1) Can any one give me the expected gains for porting a elbow and adding the lager puck? (2) After porting stock elbow would there be any additional gains in the Poston 3'' down pipe? Or does must of performance gains come from elbow? Tks Scott

I haven't compared a ported elbow to a unported elbow, but I have compared a ported elbow to a THDP. They are actually a lot closer than I originally thought. Back to back, the elbow with a 2.5" stock replacement downpipe was only .05 seconds and 1.5 mph slower than a THDP (11.84@113.5 vs. 11.79@115)

A ported elbow is great bang for the buck. It only take a few hours, even for a newby and it gives you a feeling of accomplishment that you modded your car yourself.

You open up the outlet to the OD of the donut gasket, then blend the shortside radius into a smooth curve. Also, blend away any interference between the turbine outlet and the elbow and lap the turbo mating surface flat, to reduce smelly underhood exhaust leaks.

When the elbow is ported, a 2.5" diameter (2.6 inch really) ball should drop througn the elbow. If not, keep porting.

 

[Bob Avellar]

You open up the outlet to the OD of the donut gasket,

I use a 3" downpipe and have ported the stock elbow. However, how will the downpipe seal to the elbow if you open it up to the o.d of the gasket? I wouldn't think this area will seal without the donught?