No wastegate now on my secondary: s362/68/14. I bought a 40mm gate with an 11 pound spring but I swear I have to apply 60 lbs of force to push the valve open on its face manually.

I once measured drive pressure on my stock head and got 75lbs at 45 boost.
So maybe if I waste at 1/2 of that: 38 lbs drive/23 lbs boost I guess I would be in the ballpark.

I see from your post I do want a degree of modulation on the gate and not on-off control. I was wondering about that, thanks. Something about cycling that has a waste opening, thus lowering drive pressure, allowing it to close again, and same thing over and over is a pita, I read.

What effect will a ported head have on drive pressure? More, less or the same?

I read it'll spool quicker and lower egt but DP???

My wastgate valve is 40mm or almost 2 sq. inches, so if it takes 60 lbs to manually open I would think that would corolate to 30psi of drive pressure that will start to force the valve open. If I'm shooting for 38psi DP for 23lbs boost then I need an additional 4 psi TOP of the WG to help hold it closed. guess I have to drive it to figure it out!!

S.

 

Drive pressure/boost ratios aren't linear. I'm actually quite surprised your drive is that high at 45 psi. Usually at 45 its much closer to 1:1.

Most wastegates have two ports, one to the top, one to the bottom. If your run boost to the lower port to open, and drive pressure to the top to hold it closed, then it will open at whatever your spring pressure is. Thats assuming the diaphragm is the same diameter as the valve itself. At this point, you can regulate the boost or the drive pressure to the wastegate to fine tune it.

I can't see a ported head doing much for drive pressure. I'd think a ported manifold and turbine size/housing would have a bigger effect. It also depends on where you measure it. If you measure it right at the turbo inlet, it might actually increase since you will have less frictional loss due to turbulence with a ported manifold and head. If you measured it right at the port, it would decrease since total system pressure drop would be less. Thats my theory, anyway.

 

cool. That 75 was a max recorded on the x monitor. I suppose it could have come anywhere during the full throttle run up throught the gears. I always have to watch where I'm going rather than study the gauges. Guess I need a HUDisplay Thanks Tate,
Steve
I guess the diaphram is a good 3" in diameter..http://www.tialmedia.com/documents/w3_tial_40_dim.pdf though mine is rebadged PIT.

 

Just thought I would bump this up, as I was doing some reading and John Robinson is running ~ same sized secondary as you are Kev, but with an S595 Primary, and that thing goes 7's.

 

But he is a little over half my weight,, LOL. He is also running a really loose converter and over 5000 rpm.. neither of which I have,, oh well, maybe if these stand alones are as good as they say. Or if marco can get that table figured out, my engine is ready to run 5000 as she sits now.

Hey Mike, can you let me know what you can do for data loggers?

 

Steve, have you measured the pressure at the primary and secondary? I bet that gate isn't openning, with a 40mm gate, you should be able equalize the two turbos more so. You have a diagram or pictures on how the gate is tubed in?
As Tate said, there is on side to push open (usually the bottom) and top to apply extra pressure. Pull the spring out and see whats your opening pressure. To me 60psi is way to much. I usually like to set mine around 24-26psi of pressure to start openning the gate. There is lots of variables for determining if port is or isn't any beneift. If you look at a stock head, you see that these head have awful flow patterns, restrictive. At stock power level, the stock head is good enough. For a 600+truck, you need a ported head and camshaft. It just aids in getting the air into the cylinder. I noticed a difference between a unported head and a ported head at 450rwhp. How was the head ported?

Kev, I don't think I will have time this year for that. Work is starting to get busy again.

 

I haven't installed the s475 yet. The gate is on the bench too.
I put on the ported head and a new lift pump at the same time. Now that the roads are dry and the studs retorqued I can say categorically, I have a massive power increase! Drove by AFI and all is quiet. No tracks in the snow to the bay and a car is in there so no pull possible for today.
This thing flat out hauls now... I am planning a cam sometime in the future Mike..Head was ported by Alan (I think) at Source through the ex ports and valve openings to do the minor bowl work...

 

Kev, I can find a S510-95 for you if you want to try it. I can find one with a the smaller turbine housing turbo available. I think that Robinson is running just straight fuel, and Kev running a wee bit of NOS shot.

Brett, I'm thinking about adjust the turbine housing even more on the S510. Its to big for our small inch motors or do a custom build on the T106mm. Its just abit of machining and welding to get what we need. That would be the hot secert to getting the S510 to spool decently. Even the small housing 1.15 is quite large. I have interest from the other side, as they have a few commerical projects for what ever we come-up with for a design.

 

After I get this present setup running and dialed in we might try that bad boy. John he runs some squeeze dont let it fool yah,, lol. He needs to change alot of things on that car before it is going to reach its potential.. like get rid of the intercooler and the CO2 spray.

 

I think that the smart approach. Turbos are an easy upgrade down the road. Like I said, I plan to adjust one turbo, some. They run these turbos on a few oil/gas engines, low emission stuff, the current S510, just hasn't worked out for them, so they sit in the corner. So when I told them I want to adjust things, they got interested. If a big 16V has troubles spooling and bring up that turbo to speed, imagen a 5.9L or 6.7L Last year, they had 10-15 S510 just collecting dust, tried both the smaller/larger A/R housings.

 

Seems that there are a number of guys running the S510-95 out there already, seems to be a proven turbo. I wonder if they are running a custom EH, or if there is something else that is making them work?

 

Hard to see from 10000ft whats really going on. Until we build a set and run them hard, its hard to says whats really going on. It will taking pouring throu a catalog to find what fits and what doesn't. I would like to go with a smaller housing on the turbine. Man its hugh, I don't even now how much mass flow it would take to start to spool that thing. A S510 turbine housing is nearly size of a S475 itself. I want to reduce the area inside the housing, using something, we will see how things go.

 

Im pretty sure that my 475 top would get that bad boy spinning

 

Is it a divided housing?

 

Brett, looking at the borgwarner drawings no its not. I can't remember correctly, as I thought it was. Might be a single volute, I didn't get that good of look at it, it was busy there. The darn thing is heavy, I bet its around 60-80lbs. I thought my T-88 was a big turbo. I'll share the other mods for a beer when you get back.