Turbo Maps -- your thoughts please

[Twisted Steel Performance]

I have here 2 different turbo maps, one from a GM4 and the other from a (real) Super HX40 Holset but I don't know the whole story as of yet.

The Holset is going to be used on my build for towing open road 99% of the time with a 12K trailer.

What are the thoughts from all you better turbo folks out there than me just from looking at the maps......

Idea is for towing on the open road, not for full out power in short runs.

Thoughts and opinions ????

Chris

 

[Twisted Steel Performance]

This is a compression map for the Holset HX40 & the Super HX40

 

[turbonator]

Okay Chris, since nobody else seems ready to take the plunge, I can swim.....even when guys are whacking me on the head.....LOL. If I understand correctly, on the first page of your post, the first (top map) is the Holset, and the lower is the typical GM-X map (we have only ever found a map for the GM-4). When we decided to turbo one of these engines, we calculated a need (or a want) of 52 lb/min of air......the Super 40 is just starting to work after 2000rpm, all the way to red-line (4000rpm) it is staying over 69% efficiency, and not even spinning at 100,000rpm. The GM-4 on the other hand, does not even register with our demands (better to use two GM-4 for twins). No words to describe, the map is incomplete, need to go down to 25-30% to register the air we need (and believe the 6.2/6.5L needs). These turbo's (GM-X), in my opinion, were as large a contributing factor to the cracking of blocks, breaking of cranks as anything else....end rant.

I for one am glad that the maps were posted up, it is information that is needed for anyone to make an informed/educated decision when upgrading turbo's.


This is the type of info out there for the GM-X series turbo's...LOL.

http://www.thetruckstop.us/forum/showthread.php?27552-Gm-8-compressor-maps-and-technical-data


I need to take more time to study the second page.....will post up again.....J&J.

 

[GM Guy]

how does one go about getting a turbo map "mapped" as in how its done, and what does it cost? It would sure be interesting to see the progression of the GM series of turbos, like comparing the GM1,3, and 4 to the 5,6, and 8.

 

[turbonator]

Usually a turbo has a design and testing parameters, these are used to verify that a turbo falls within the manufacturers tolerances. This is what we call the turbo maps, most brand name turbo manufacturers furnish the maps to aid in customer selection of a turbo. Just have not found many for the GM-X series turbos, kinda funny, when you think about it, almost like someone did not want us to see the maps of the turbo GM was using...LOL. Not sure where to get a turbo tested, someone else on the site will know though.... and thats teamwork.

 

[L98TPI]

how does one go about getting a turbo map "mapped" as in how its done, and what does it cost? It would sure be interesting to see the progression of the GM series of turbos, like comparing the GM1,3, and 4 to the 5,6, and 8.

I see a big test rig with something along the lines of a roots blower driven by a motor bigger than house wiring would run, with variable speed on the drive side to spin up the turbo. On the compressor side I see pressure gauges and flow meters and a valve to provide variable back pressure. You would have pressure and flow meters on the exhaust side as well. You would have to have a set of factors to make calculations that would relate the results back to hot exhaust gas flow. Not a trivial thing (compared to say a head flow bench) and likely more complex than I have outlined.

Man I hope whomever store my Turbocharging book burns in hell, :firedevil: I miss it.

 

[Twisted Steel Performance]

Okay Chris, since nobody else seems ready to take the plunge, I can swim.....even when guys are whacking me on the head.....LOL. If I understand correctly, on the first page of your post, the first (top map) is the Holset, and the lower is the typical GM-X map (we have only ever found a map for the GM-4). When we decided to turbo one of these engines, we calculated a need (or a want) of 52 lb/min of air......the Super 40 is just starting to work after 2000rpm, all the way to red-line (4000rpm) it is staying over 69% efficiency, and not even spinning at 100,000rpm. The GM-4 on the other hand, does not even register with our demands (better to use two GM-4 for twins). No words to describe, the map is incomplete, need to go down to 25-30% to register the air we need (and believe the 6.2/6.5L needs). These turbo's (GM-X), in my opinion, were as large a contributing factor to the cracking of blocks, breaking of cranks as anything else....end rant.

I for one am glad that the maps were posted up, it is information that is needed for anyone to make an informed/educated decision when upgrading turbo's.


This is the type of info out there for the GM-X series turbo's...LOL.

http://www.thetruckstop.us/forum/showthread.php?27552-Gm-8-compressor-maps-and-technical-data


I need to take more time to study the second page.....will post up again.....J&J.

Thanks, J&J, the first map is a Super HX40 with Ron Schoolcraft's mods, I found it on his web site, if you look at it close, it is different from the 2nd post with the 2 Holset's together. Ron is going to mod my super for me, I do know that everything is done to the turbine side, the super 40 is the turbo he used in the "Page" pull off's a while back, and I am sure you have read the story. All I can say, as it is all I know, is that there is no machining needed, and it is something that Holset says can't be done to there turbos, BUT Ron did it, and the modded Super 40 is the one he has on his truck and his web site.

I just posted them as I haven't seen a map for the K/O 40's yet??

The changes he does to them, changes the spool up RPM some at the bottom and will stay high further than out motors will ever see. To quote Ron, " The super 40 with the right mod is the best turbo for towing heavy, keeping EGT, & temps down and power up"

He did ask me how I came to chose the super when VERY few even look at it.........:thumbsup: