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Gonna add a turbo section soon here. Anyone have any feedback for me, any links that need to go in here, anything to make it better and more informative???
for guys like me, it would be nice to know what stock turbo we have and what its capabilities are. like how much psi, when it should be lit by, what hp it is capable of handling. things of this nature. for alot of the newbs like myself it may be awhile before we can afford a new turbo, so we would like to know how to squeeze every once out of what we got in the process. thanks 12veg!
 

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Discussion Starter #22
I'll squeeze information of that nature into the turbo section. Thanks for the feedback.
 

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I'll squeeze information of that nature into the turbo section. Thanks for the feedback.
also like what jkidd posted up that you are wanting to put in here! that is extremely helpful. what is the compressor wheel vs the turbine? i am about to google it and throw some help in here for you.
 

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definition of compressor wheel
•The fan blades that suck in the intake air and compress it against the compressor housing and backplate.
 

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Keep your temps low so you do not melt pistons or warp turbine wheels on the turbo.
I know there will be plenty of people that disagree but think of this as a rough guide: sustained temp of 1100
1200 for 30 seconds,
1300 for 10-15
1400 for 5
higher... why??? Thats why they make bigger turbos and products for better airflow like the tunnel ram, 3pc manifolds, cams, water injection, porting etc

Keep your boost low so you do not blow your head gasket.
Keep your drive pressures low so you do not create a restriction on the exhaust side causing unnecessary boost/restriction or blow your head gasket
Do not overboost as you will overspeed the turbo and run the turbo beyond its efficiency range = hot boost and less dense air = less effecient and expending MORE energy to be less efficient.
hy35 =280hp 28psi
hx35= 300hp 32psi
35/40=350hp 35psi (bigger compressor wheel but same 3" turbine outlet and bad wastegate design)
hx40 or he351 =400hp 40psi (4" outlet, he351 has good wastegate and super40 wheel, but 9cm housing so I am putting it slightly behind the super40 with 16cm housing)
s300 57/65/14 (like superB) or super40=425HP 42psi
s300 62/65/12=450HP 42psi
s300 62/71/14=500HP 45psi

You can run bigger/hotter than the list, but expect decreased turbo life, head gasket problems and risk overheating cylinders 1 & 6 which run hot anyways. (a good stock turbo is still worth $300, a blown one is worth $0-100 if it can be rebuilt)
 

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Keep your temps low so you do not melt pistons or warp turbine wheels on the turbo.
I know there will be plenty of people that disagree but think of this as a rough guide: sustained temp of 1100
1200 for 30 seconds,
1300 for 10-15
1400 for 5
higher... why??? Thats why they make bigger turbos and products for better airflow like the tunnel ram, 3pc manifolds, cams, water injection, porting etc

Keep your boost low so you do not blow your head gasket.
Keep your drive pressures low so you do not create a restriction on the exhaust side causing unnecessary boost/restriction or blow your head gasket
Do not overboost as you will overspeed the turbo and run the turbo beyond its efficiency range = hot boost and less dense air = less effecient and expending MORE energy to be less efficient.
hy35 =280hp 28psi
hx35= 300hp 32psi
35/40=350hp 35psi (bigger compressor wheel but same 3" turbine outlet and bad wastegate design)
hx40 or he351 =400hp 40psi (4" outlet, he351 has good wastegate and super40 wheel, but 9cm housing so I am putting it slightly behind the super40 with 16cm housing)
s300 57/65/14 (like superB) or super40=425HP 42psi
s300 62/65/12=450HP 42psi
s300 62/71/14=500HP 45psi

You can run bigger/hotter than the list, but expect decreased turbo life, head gasket problems and risk overheating cylinders 1 & 6 which run hot anyways. (a good stock turbo is still worth $300, a blown one is worth $0-100 if it can be rebuilt)
i just got my boost and egt gauge in. under wide open throttle with the tq converter locked i will run 1200-1240* for about 4-8seconds. cruising down the road at 76mph i run 920-960* pulling a pretty good hill, i run about 860-880* flat ground. under full spool stock hx 35 turbo im putting out 33-34psi, my drive pressure at 76mph on flat ground is about 3-5psi and pulling a hill about 12-15psi. let me know if this is acceptable or not jacob, thanks
 

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drive pressure is the pressure on the exhaust side instead of the intake side.
 

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not needed for most trucks, but is helpful for tuning the wastegate to where you want it. try to stay at 1:1 ratio of boost and drive pressure.

for example: if you were to be at 50psi say on an he351 your drive pressure will probably be closer to 70psi
 

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not needed for most trucks, but is helpful for tuning the wastegate to where you want it. try to stay at 1:1 ratio of boost and drive pressure.

for example: if you were to be at 50psi say on an he351 your drive pressure will probably be closer to 70psi
how would you keep the tubing from melting with the temps gettin 1000* plus? also do you think my exhaust temps are good or should they be lower?
 

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use copper tubing for drive pressure.

your temps seem to be in the norm.
 

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not needed for most trucks, but is helpful for tuning the wastegate to where you want it. try to stay at 1:1 ratio of boost and drive pressure.

for example: if you were to be at 50psi say on an he351 your drive pressure will probably be closer to 70psi
I always thought it was impossible for drive pressure to exceed the exhaust valve spring rating.
35 psi stock or 60 psi modded.
 

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I always thought it was impossible for drive pressure to exceed the exhaust valve spring rating.
35 psi stock or 60 psi modded.
Maybe someone who knows more than me can explain better:S:. The 60# valve spring are supposed to be 60# greater than stock.

As I understand it the drive pressure is the pressure that is between the exhaust manifold and the turbo. Those with wastegates closed off or running a turbo with a small non-wastegated housing can have a big restriction if they do not have a wastegate that allows the the extra air to bypass the turbine wheel reducing the pressure and helping to keep the turbo from overspeeding and creating excess boost leading to even higher drive pressure.

for instance the 71mm turbine wheel is called the LDP or low drive pressure wheel and because drive pressure is lower (and slightly more mass of the larger wheel) during normal driving the turbo does not spool as well, but at higher RPM and higher boost it allows the air to flow more freely out of the engine and manifold.

As for max drive pressure being limited by valve spring seat pressures... I am not sure how it would limit it because the design of the manifold, turbo/wastegate and to a small degree the exhaust would be the greates contributing factors.
 

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Shouldn't the output for turbos be limited by so many times barometric pressure, instead of total psi? I drive at 0-500 ft and have a 62/65/12 turbo. At my level 48 psi apears to be inside the map, whereas someone in Denver is pushing it at 40psi. Is that right, or is there more to it than that?
 

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My main experience with drive pressure is from installing exhaust brakes.
I was told by BD if you exceed the valve spring rating by blocking off the exhaust with the brake at higher rpm that the pressure will max out the spring rating while the valves are floating and getting damaged.
 

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Illflem I work mostly with the vp44 trucks which have greater spring pressure. I had not really looked into it for 12v. That information is good to share. I'm sure you know more about exhaust brakes than me. If I remember there are some design features to protect the engine from the scenario as you discussed, like a small hole in the plate that blocks off the exhaust flow, and they tell you to get the 60# over springs for at least the exhaust side. Wish I had more info to contribute specific to the 12v.

Drothgeb You are right that a turbo will be out of its map earlier at a higher altitude. The maps are for a pressure ratio. If you are at sea level it is 14.7psi absolute pressure, double is 29.4psi which would read 14.7psi at sea level. for each 1000ft in elevation you lose roughly 0.5psi. If you were at 6000ft your absolute pressure would be roughly 11.7psi and so it is harder for the engine to get more air because it is less dense.
 

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Turbo drive pressure will not blow open the valve springs because the boost pressure is acting on the other side of the valve to counter that.
When you use an exhaust brake you don't have any boost pressure so the valves can blow open.
 

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Discussion Starter #38
update coming soon here everyone, in the middle of moving. Thanks for all of the info and feedback...
 

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Hope the move goes well Nick. Wish I lived closer, I'd give you a hand and another truck.

It's weird that I can't find any information when searching for the pound-rating of the stock vs HD exhaust valve springs.

The HD valve springs are 60# *over stock*, but it's hard to find the actual spring rates of each one. Then there are the 110# (over stock) springs that are mostly for 24valvers, but I guess some pullers use them on 12 valves. ??

Seems like it wouldn't be too hard to check if you have both laying around. I don't.

I still have stock valve springs. That should be next on my list... then I can do a valve adjustment too, which I'm sure has never been done to my truck. :doh:
 

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Discussion Starter #40
Hope the move goes well Nick. Wish I lived closer, I'd give you a hand and another truck.
Hah, thanks man. Luckily the hard part is done, I used my dad's flatbed for the big stuff. Now it's all the little stuff...

Turbo section added, feedback welcome...:thumbsup:
 
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