How many horses it too much for a 38mm wg? I have a t67 and wanted to know if I could get away with a 38mm and still push 400-500 lo/hi boost? I heard that low flow or something like that for wg holds boost better??? Could be wrong, that's why I'm asking. Thanks

 

you have a t67 and your "high" boost is 500?

 

No, I want to make around 400-500 hp. The hi/lo will differ of corse. I want to know can a 38mm wg support 500hp if I chose to keep the wg? I should have worded it like that. sorry

 

As i understand it but i may be wrong, it may work but if you ever want to run lower boost settings, a larger wastegate will prevent boost creep. I think a larger wastegate would be a better option all around though, preventing boost spikes as well.
someone correct me if im wrong

 

the 38mm would work , remember before they made 44mm everyone had 38.
remember the purpose of a waste gate, the larger it is the more pressure/air it lets out, serving its purpose.
as stated before the larger wastegate would be a better option

 

What type of manifold are you planning on running? 38mm will be fine with a ramhorn type...like stated lower boost you may get some creep..but if your going with a top mount, why not go with 44mm?

 

go with the 44mm, if you search the archives there are alot people that have had issues with the 38mm on a ramhorn when using a big turbo such as the t67.

 

A 44mm should be your only choice, having a boost creep issue can be very aggrevating. I dont think a 38mm gate would hold boost steady and near the spring level even with a FR Manny. I run a T67 and a 44mm gate that doesnt have the most ideal placement and I hold 14-15lb pretty stable on a 13lb spring.

 

Wastegate sizing is always a misconception people always think that more exhaust gases is discharged at lower boost levels this its true to an extent, but the real need for a larger wastegate if you think of it from a different perspective of airflow. Larger turbos flow more which increases as boost pressure increases, when you force a certain amount of CFM into the engine what do you expect to come out the exhaust side? The same amount of CFM airflow. Just because the wastegate take longer to open doesn’t mean it releases less exhuast gases. From a physics point of view, mass flow in equals mass flow out. So if you’re experiencing boost creep which is cause by wastegate placement or lack or flow, then I would upgrade. Personally I put down 462whp on 20 psi on stock sleeves and pump gas with no problems of boost creep with an afi ramhorn and 38mm tial.

 

If what you say is true, why are exhaust valves smaller than intake valves? Flow in does NOT equal flow out.

The amount of flow a wastegate provides is not based on the size of the valve alone. It is also dependent on the distance it opens (lift) and that area is referred to as skirt area.

 

I have an afi ramhorn and that is what I'm using. Lots of info to digest. If I'm understanding correctly, I should get a 44mm wg to be safe?

 

you should go with 44mm better boost control at those power levels. But if you already got everything for 38mm I think you should be alright.

 

gotcha. I think I'll do that. If I have any issues, then I'll upgrade when the funds are handy, rather than delay my fun any longer. lol. It should be evident when I retune with the t67. Thanks guys

 

i would run the bigger wastegate for sure. Creep can be a big pain. I've seen plenty of cars with 10psi springs, a big turbo, and too small of a wastegate that would be hitting 20psi by redline with no boost controller. Its quite annoying if you are trying to run lower boost at any time.

 

because restriction on the exhuast side isn't as critical as it is on the intake side because exhaust gases are forced out

 

ok so sohc_mshue is refering to me LMAO...

i got a t3t67 with 38mm 10psi spring and i got boost creep. suppose to be holding 17 pounds but im spiking to 20 psi... so yes upgrade to 44mm dont risk blowing your motor because you didnt pay the extra money when you had the chance. do it right the first time... i thought i did but apparently i didnt. i will be upgrading to a 60mm later

 

Oh... sorry. Wanna try again?

You mix fuel and oxygen and ignite it... what happens to all the energy? Where does it go? What does it do? 500CC's of air and fuel in does not equal 500cc's of something else out the exhaust.

 

Just wondering, does a mbc or electronic matter? What are you running with? I have an turbox mbc installed now and I'm trying to find someone who knows how to uses the greddy specb2 to install that. Does that matter though?

 

Get a EBC, the Greddy Specb is easy to install and use I have it and did all that comes with decent instructions, the over boost function is a must have if your running pump gas.

 

boost cut is a must feature you never know when something can go wrong with your wastegate, with boost controller or any of the lines. Next thing you know your engine goes boom.

 

So if I have the specb2 and keep the 38mm could I be ok? I'm running the 38 with the manual set at 17psi now. No creep or spikes.

 

You will see when you turn up the boost. It all depends how your engine/turbo/manifold flows and how much exhaust will need to get dumped off before it reaches the turbo.

 

i hear ya. thanks