Anyone running a THDP with a 6262?

[Jay J]

Getting ready to install the engine, and figure if a new DP is needed, now would be the easy time to do it. The puck diameter is (roughly) 1.375 " and the wastegate hole in the turbo is approx. .955". Assuming (I know!) that it is centered on the hole, is that enough coverage for good boost control?

 

[Jay J]

Well-is this Board great or what!? Just discovered a post by Coach (Thread was in General Buick Tech, title: RJC Boost Controll) stating that as long as the puck is centered, you only need .05" overlap to control boost. I will mark it and measure to see if it is close to center and run w/ the THDP... If any of you have thoughts or comments, please chime in.

 

[bison]

If you want to run the turbo near it's potential the hole should be smaller. If you want to run it at 50lbs/min it will need to be as large as you can make it

 

[we4Mateo]

If you want to run the turbo near it's potential the hole should be smaller. If you want to run it at 50lbs/min it will need to be as large as you can make it

Couldn't you just make the hole bigger and then wire the gate shut or just put an extra spring on the actuator when you wanted to run it harder?

 

[Jay J]

If you want to run the turbo near it's potential the hole should be smaller. If you want to run it at 50lbs/min it will need to be as large as you can make it

Bison: All the old school stuff I ever heard said that you had to increase the size of the hole. With that in mind, I had even considered opening it up a bit larger, but since the 6262 is new turbo for me, and this is a new stroker, I was going to run it as it was sent. So you will know,it is, and has been a street car that will never be pushed to its ultimate potential. (Well, not yet anyway). Pump gas for now, which is a definite limiting factor. Alky will come later, after this new combo is dialed in. I am at 1 mile of altitude with all the bad air/octane that we live with here. The engine has been overbuilt for now, with hopes for power/trans/suspension upgrades as $$ permit. I have had these cars for many years now, but have never really tried to find their limits. Its just too damn expensive to blow sh%t up these days. The information shared here has really made me want to explore the limits.
Sorry for the length. Just trying to find the right combo!

J

 

[we4Mateo]

Bison: All the old school stuff I ever heard said that you had to increase the size of the hole. With that in mind, I had even considered opening it up a bit larger, but since the 6262 is new turbo for me, and this is a new stroker, I was going to run it as it was sent. So you will know,it is, and has been a street car that will never be pushed to its ultimate potential. (Well, not yet anyway). Pump gas for now, which is a definite limiting factor. Alky will come later, after this new combo is dialed in. I am at 1 mile of altitude with all the bad air/octane that we live with here. The engine has been overbuilt for now, with hopes for power/trans/suspension upgrades as $$ permit. I have had these cars for many years now, but have never really tried to find their limits. Its just too damn expensive to blow sh%t up these days. The information shared here has really made me want to explore the limits.
Sorry for the length. Just trying to find the right combo!

J

With just pump gas, don't run it as it comes. You'll have boost creep and quickly be making too much. As Bison stated, leave the hole only if you plan to run it all out.

 

[Sweet6]

I found the most important part of porting the hole is contouring the bottom of the hole. Smoothing out the ridge of the hole from the inside. Just doing that might work. Or open the hole up a little too.

 

[bison]

Couldn't you just make the hole bigger and then wire the gate shut or just put an extra spring on the actuator when you wanted to run it harder?

You could but it won't be consistent and you're creating enough variables with an internal wastegate strategy that had R&D with a small turbine and relatively low mass flow levels compared to what people try to do. The cross sectional open area will determine the mechanical advantage of the ex pressure. Once the valve cracks open it will cause a big pressure drop the more the hole is opened.

 

[bison]

I found the most important part of porting the hole is contouring the bottom of the hole. Smoothing out the ridge of the hole from the inside. Just doing that might work. Or open the hole up a little too.

I've tested this before and after and found little difference unless the turbo was being under used. The cross section of the hole was by far the biggest contributor to reduced ex pressure.

 

[TT/Ameasap]

The bigger you make that hole, the more pressure you have on the puck. If opened up too much, a certain amount of surface area (at higher boost levels) and the puck will eventually open prematurely.
I radius the inside and open up the cross section just enough for boost control.