Tahoe Motor Is Blown Up

[buddy]

6.2 turbo, do you have an intercooler on there? If so, for the turbo to support 40psi it would have to spool more to support the additional mass flow, more CFM of atmospheric air at the inlet of the compressor housing. This would mean even higher drive pressures for the same boost as a non-intercooled engine, just a lot more mass flow. But it could be a major detrement as RPMs increase.

 

[6.2 turbo]

No intercooler. I want to do that or water inj . The HX52 is not a small turbo,sometimes it would surge if I shifted to 3rd to early at full throttle. Cruising at 2500 in any gear ,it would light to 43 psi instantly by giving it full throttle. Free revving produced no boost,unlike my H1C on my 92 . I also noticed that free revving with dual open manifolds,was nice and snappy. Once I bolted on the turbo manifolds, and 2-1/4 crossover,it sounded like crap,and the snappiness was gone. This was without any turbo. I have one HY35,if I had two I would seriously attempt twin turbos. For some reason 6.5 diesels have a lot of exhaust flow.

 

[littleboy]

Hx-52 will support an easy 600 hp. have seen them do over 700 already.
They are factory turbo for a 12 liter truck engine. They flow very well . I dont follow your thinking on backpressure.

 

[buddy]

What are the specs on this HX52? It seems too big on the compressor side and too small on the turbine side.

It all depends on the engine. The Volvo for instance, makes its power at 1500rpm, only 405CFM at governed 1900rpm, which happens to be the 6.5s CFM around 3500rpm. And the D12 only pushes about 25psi of boost. Its turbo has some exhaust braking function, is that on the PRO52? It restricts the exhaust flow.

And a lot of the high horsepower applications seem to be high revving gas engines, but at lower boost than 6.2Turbo is running. Those applicatios also probably have camshafts with valve overlap and divided exhaust so that it can actually scavenge the remaining exhaust by pushing it out with boost. whereas the 6.5 cam closes the exhaust valve about 16 degrees before TDC, trapping the hot pressurized exhaust in the cylinder. The more backpressure, the more pressure in the cylinder when the valve closes to mix with intake air. You'll actually lose about 7hp for every 10psi of backpressure from the work the piston has to do to push the exhaust out. And then there is the work the piston has to do to compress the air, which if it is leaning the mixture to greater than 18:1 air to fuel may be a much bigger waste of hp.

Rather than using parasitic boost to incease mass flow, it would be more efficient to lower the boost and incease mass flow with an intercooler.

 

[littleboy]

The hx-52 does not have an exhaust brake function! The volvo application has an exhaust brake after the turbo. We use them on a 5.9 Cummins and they work like a charm up to 65 psi. Can easily make 500 hp on the 5.9 at 50 psi and 1200 for ehaust temps!! The pro 52 has a bigger turbine wheel for less drive . Don't have the numbers on the pro turbine wheel in front of me at the moment. The compressor wheel is a 67mm inducer and the pro has a 71 mm or you can mix and match wheels however you want. We have a couple sitting here in the shop...

 

[buddy]

What RPM are you running the Cummins to and what is the overlap of the cam? Does it have divided exhaust manifold? What kind of fuel rates do you get on those engines?

 

[littleboy]

Ok , just looked at a couple of the ones on the shelf and i found one that has a 64 mm inducer with a 98 mm exducer. The exhaust is 71 mm . What i am a little puzzled about is over at the other diesel place you told a guy that the 55 would be a good choice for a big turbo on a compound setup. But here you say a 52 is too small. They are the same wheel sizes with the main difference being the 55 has bigger housings. Explain your logic.

The cummins are limited to 3800 rpm with divided manifolds.

 

[buddy]

Its all dependent on your fueling, most 6.5ers arent going to modify thier IPs and arent going to run 40psi of boost. I'm not saying that the exhaust side is too small for a 6.5, I'm saying its creating too much boost with its compressor, and an HX40 could create 40psi too, but we pop the wastegate well before that to prevent high drive pressures because the extra boost doesnt help with the fueling level.

I have seen 52s have a 16cm^2 turbine housing, its basically the same hot side as some of the HX40s guys are running that have the 85mm inducer turbines, but only 10-blades. The 22cm^2 housing of the HX55 would be a completely different animal, way way different, especially running a smaller turbo before it in the exhaust stream, not exposing it to the full drive pressure because some of the heat is going into spooling the first turbo. And the HX55 has a turbine exducer of like 77mm, compared to 71mm of the HX52, so it wont spool as much.

 

[littleboy]

Where did you get info that the 55 has a 77 mm turbine wheel? I've only ever seen 71 on a 55 and have tried to get bigger but can't find them, even in the aftermarket. And the 55 is not limited to the 22cm housing.

 

[buddy]

The 22cm^2 housing is just the one I recommended as a secondary. Do you have the RPM, valve timing and fuel rate details on the 5.9s you run with the HX52?

Since I couldn't find a good reference for sizes on the 55 I found this first which was someone measuring the wheels
http://www.cecoatings.com/images/CarStuff/92Z/TurboMotor/HolsetHX55Turbo/

This one is the turbine
http://www.cecoatings.com/images/CarStuff/92Z/TurboMotor/HolsetHX55Turbo/DSC00763.JPG

and he is measuring just over 3", maybes its like 2mm off but its more than 71mm.

Is there a nice reference sheet for Holset wheel and housing sizes?

 

[uniquediesel]

Ptdc=Pbdc x CR^1.4 where 1.4 is the specific heat ratio of air -> Ptdc = (35psi+14.7psi) x 17^1.4 = 2624psi

Um, wrong math there bud. You're not helping here one IOTA, I'm not going to banter back and forth with you. I'll talk to someone who does this for a living and knows his stuff. Not getting that from you.

 

[buddy]

Um, wrong math there bud. You're not helping here one IOTA, I'm not going to banter back and forth with you. I'll talk to someone who does this for a living and knows his stuff. Not getting that from you.

I didnt make it up. You cant just multiply by CR because it doesnt account for the heat generated by compression, and with heat the gas expands even more making more pressure. You can look this up for yourself, you go do the research instead of asking someone that doesnt know.

 

[littleboy]

The 22cm^2 housing is just the one I recommended as a secondary. Do you have the RPM, valve timing and fuel rate details on the 5.9s you run with the HX52?

Since I couldn't find a good reference for sizes on the 55 I found this first which was someone measuring the wheels
http://www.cecoatings.com/images/CarStuff/92Z/TurboMotor/HolsetHX55Turbo/

This one is the turbine
http://www.cecoatings.com/images/CarStuff/92Z/TurboMotor/HolsetHX55Turbo/DSC00763.JPG

and he is measuring just over 3", maybes its like 2mm off but its more than 71mm.

Is there a nice reference sheet for Holset wheel and housing sizes?

Holset is almost as tight with there turbo info as a certain shady character on here that sells a phony turbo.

 

[6.2 turbo]

With just a regular turned up DB2 the turbo would not light. I think it made 25-28 psi at max rpms .

 

[littleboy]

I for one would like to see some specs on the att turbo as it seems to spool at similar rpms as the hx-52. We have specs on these other turbos , let's get some for this seemingly special turbo.

 

[buddy]

I would like to hear more specs about the Cummins that run 60psi, such as RPM range, valve timing, and fuel rates. I dont know all about the Cummins, but some of that info can help explain the differences someone might experience compared to the 6.5. We already know the Cummins is built a lot stronger, and is naturally better balanced.

And if anyone was really doubting how the compression of air acts maybe you'll believe NASA
http://www.grc.nasa.gov/WWW/k-12/airplane/ottoa.html

To have volume and pressure act in a proportional manner (just a multiple of CR) completely defies the gas law. If cylinder compression really worked that way the temperature would never change.

The ideal gas law only works with the correct units, so the temparture equations must use Kelvin, because its not a simple proportional value to Fahrenheit or Celcius. The pressure alone equation you can use PSI because PSI has a linear proportion to Pascal units, so converting before or after the math is the same. But if you ever use an equation with both Temp and Pressure has to use Kelvin and Pascal units when using the appropriate value of the constant R. The volume units would be cubic meters when used in the equations with Temp and Pressure.

 

[buddy]

With just a regular turned up DB2 the turbo would not light. I think it made 25-28 psi at max rpms .

That sounds like more than enough boost , and for littleboy this is what I mean by most users will be using regular pumps turned up. If the 16cm^2 housing HX52 can only make 25psi, the 22cm^2 HX55 will struggle to hit 15psi of boost.

If wanting to run high boost like 40+ psi a single turbo is not ideal on a GM 6.5L, and the compound setup would be much more efficient for lower drive pressures and better exhaust flow for higher RPMs.

 

[littleboy]

That sounds like more than enough boost , and for littleboy this is what I mean by most users will be using regular pumps turned up. If the 16cm^2 housing HX52 can only make 25psi, the 22cm^2 HX55 will struggle to hit 15psi of boost.

If wanting to run high boost like 40+ psi a single turbo is not ideal on a GM 6.5L, and the compound setup would be much more efficient for lower drive pressures and better exhaust flow for higher RPMs.

So...... you have run compounds and have proven your THEORY?

 

[buddy]

You keep making snide remarks but refuse to provide any of your info.

I have not proven it personally, its it is an educated hypothesis, made from science and real world applications other than the 6.5.

 

[littleboy]

You keep making snide remarks but refuse to provide any of your info.

I have not proven it personally, its it is an educated hypothesis, made from science and real world applications other than the 6.5.

From real world experience i have never seen a set of compound turbos get anywhere close to a 1-1 drive ratio. They end up closer to 2-1 drive ratio than they are 1-1. Your science and math have nothing on real world experience.