Does anyone have a compressor map for a PT51?

[88GTAinRI]

I am looking for a compressor map for a PT51 turbo. A JPEG or link would be cool. I don't know why I am having such a hard time finding one in a google search and I have searched here as well. Thank you in advance.

 

[LUCKY1313]

Your probably not going to find one. Compressor maps are very expensive to get done for a turbo and most aftermarket turbos dont offer suck.


Your best bet is feedback from other users to see if it meets your needs.



I may be totally wrong about no map for the PT51, but I have never seen one. If you can find out exactly which wheels it has in it there may be a garret turbo with a map that will come close if your trying to use the info in a calculator or such.

If there is a map for this turbo maybe someone will chime in with the info.

Jess

 

[88GTAinRI]

Thanks Jess. I teach a class and we where doing mapping the other day. My students wanted to map mine out. I was thinking of your suggestion if I come up empty. Find the closest Garrett and see if the have the map.

 

[JZ 97 SS 1500]

Closest one you'll find..... 58mm

 

[RUQWKNF]

Just to add more...

You won't ever find one, cause getting one done through official channels (Garrett) back when that turbo was first introduced by PTE, would have cost somewhere around $15K. Jose is right about that map being the closest one available. But, just remember, the map drastically changes when you put a different compressor cover and turbine housing on it. What we don't know from that map, is what comp cover and turbine housing it had on it when it was made.

The PT51 was typically good for 500-550 flywheel hp maxed out, depending on your combo. Which was at around 27-29psi and that's really pushing that compressor wheel hard. IE: Very hot air and your intercooler had better be up to the task at hand. It got a bad rap in it's infancy, but those issues were eventually ironed out.
HTH

Patrick

 

[benoitthegr8]

Ruqwknf

Patrick,
I purchased a low mile PT-51 from a member on this board, he had a 11.08 pass on this turbo w/ 25psi of Boost. Judging on the above compressor map it looks like this turbo hits it's sweet spot at 26+ psi. What would be a safe level to run this turbo with my below setup unopened long block, running 93 oct w/alky and not risk turbine implosion. I don't know anyone that has run one of these besides Red from EVTB, and his opinion is probably not impartial as your's would be.

thanks,
Ben

 

[88GTAinRI]

Thank you to all for the usefull information.

 

[RUQWKNF]

Patrick,
I purchased a low mile PT-51 from a member on this board, he had a 11.08 pass on this turbo w/ 25psi of Boost. Judging on the above compressor map it looks like this turbo hits it's sweet spot at 26+ psi. What would be a safe level to run this turbo with my below setup unopened long block, running 93 oct w/alky and not risk turbine implosion. I don't know anyone that has run one of these besides Red from EVTB, and his opinion is probably not impartial as your's would be.

thanks,
Ben

As said before, that map is not dead on for the PT51, it is merely the closest map ever published by Garrett.

Here's the kicker.... 50# injectors.
With alky and 50's you will be running low on gas if you run over 30psi on that turbo. Also, you will need a chip that has the capability to run 100% duty cycle on those 50's #ers, just to be safe. Maxed out, 50#ers will safely support 600 flywheel hp. You will be getting close to that level if you maxed out the turbo. That turbo with 50's and alky is a nice streetable combo for sure. I would be concerned with the condition of the internals and the turbine wheel on that used PT51, eventhough it's a low mileage unit, before just going willy nilly with the boost knob. But you should be fine running it at 26-27psi.

What we really need to know is, what is the T350 turbine wheels' death point? This can be determined with a turbine wheel map, but those are non existant and are not published by Garrett. The Stage 5 turbine wheel from Turbonetics is close, but not exactly the same. And even if the true Garrett map was availalbe, it wouldn't be applicable with our Buicks' 3-bolt style turbine housing. From what I can remember, we did not recommend running that turbo much past 30psi, as you are running very close to the edge of both wheels stay in one piece. IE: Not exploding due to overspeed condition. The easy way to figure out a turbos limits, and this is true for any turbo, would be to run a back pressure gauge. Some people have made homemade back pressure gauges by plumbing a copper tube line just below the inlet of the turbine housing, into the header, coil it around a bunch to help cool the line and the signal, and run a pressure gauge that can read up to 100psi.

The general rule of thumb is, once you reach the 2:1 back pressure to boost level, your turbo is done. Example, your boost gauge reads 30psi of boost at the intake and your back pressure gauge shows 60psi, you're done. But, if it shows less than 60psi on the back pressure gauge, either keep pushing it till you blow the heads off the motor, or over speed the turbine wheel and or compressor wheel. This can be a very fine line to figure out, not too mention a costly one. Just ask all the serious Import guys who are twisting hard on GT42 & GT45 turbos. It's nothing for those guys to run 40+ psi, but we'd blow the heads off our motors at those boost levels. The other issue with running very high boost levels is charge temps going out of control. This can be somewhat combated with Alky and an efficient front mount, but it's not good to really run any rotating assembly at the ragged edge over and over again. I mean, we're talking about 140-170K RPM levels here for the rotating assembly. Things can happen really fast if something comes appart.
Sorry to ramble on, hope some of this helps a little.

Patrick

 

[benoitthegr8]

As said before, that map is not dead on for the PT51, it is merely the closest map ever published by Garrett.

Here's the kicker.... 50# injectors.
With alky and 50's you will be running low on gas if you run over 30psi on that turbo. Also, you will need a chip that has the capability to run 100% duty cycle on those 50's #ers, just to be safe. Maxed out, 50#ers will safely support 600 flywheel hp. You will be getting close to that level if you maxed out the turbo. That turbo with 50's and alky is a nice streetable combo for sure. I would be concerned with the condition of the internals and the turbine wheel on that used PT51, eventhough it's a low mileage unit, before just going willy nilly with the boost knob. But you should be fine running it at 26-27psi.

Thanks for the reply... I figured running all up to 25psi would be safe on my set up... the only thing I was worried about was my inefficent I/C maybe letting things get too hot, thus something failing. But from what your saying I'm gathering that at those levels alky will keep everthing in check..

Ben

 

[JZ 97 SS 1500]

As said before, that map is not dead on for the PT51, it is merely the closest map ever published by Garrett.

Here's the kicker.... 50# injectors.
With alky and 50's you will be running low on gas if you run over 30psi on that turbo. Also, you will need a chip that has the capability to run 100% duty cycle on those 50's #ers, just to be safe. Maxed out, 50#ers will safely support 600 flywheel hp. You will be getting close to that level if you maxed out the turbo. That turbo with 50's and alky is a nice streetable combo for sure. I would be concerned with the condition of the internals and the turbine wheel on that used PT51, eventhough it's a low mileage unit, before just going willy nilly with the boost knob. But you should be fine running it at 26-27psi.

What we really need to know is, what is the T350 turbine wheels' death point? This can be determined with a turbine wheel map, but those are non existant and are not published by Garrett. The Stage 5 turbine wheel from Turbonetics is close, but not exactly the same. And even if the true Garrett map was availalbe, it wouldn't be applicable with our Buicks' 3-bolt style turbine housing. From what I can remember, we did not recommend running that turbo much past 30psi, as you are running very close to the edge of both wheels stay in one piece. IE: Not exploding due to overspeed condition. The easy way to figure out a turbos limits, and this is true for any turbo, would be to run a back pressure gauge. Some people have made homemade back pressure gauges by plumbing a copper tube line just below the inlet of the turbine housing, into the header, coil it around a bunch to help cool the line and the signal, and run a pressure gauge that can read up to 100psi.

The general rule of thumb is, once you reach the 2:1 back pressure to boost level, your turbo is done. Example, your boost gauge reads 30psi of boost at the intake and your back pressure gauge shows 60psi, you're done. But, if it shows less than 60psi on the back pressure gauge, either keep pushing it till you blow the heads off the motor, or over speed the turbine wheel and or compressor wheel. This can be a very fine line to figure out, not too mention a costly one. Just ask all the serious Import guys who are twisting hard on GT42 & GT45 turbos. It's nothing for those guys to run 40+ psi, but we'd blow the heads off our motors at those boost levels. The other issue with running very high boost levels is charge temps going out of control. This can be somewhat combated with Alky and an efficient front mount, but it's not good to really run any rotating assembly at the ragged edge over and over again. I mean, we're talking about 140-170K RPM levels here for the rotating assembly. Things can happen really fast if something comes appart.
Sorry to ramble on, hope some of this helps a little.

Patrick

Bingo to what Patrick said. Backpressure is the key, and overspinning is what usually kills the units, either due to a LCF failure or a oscillation which goes through the assembly as you pass the assembly's rpm limit.

 

[Syclone0044]

Wow, Patrick's #8 post was one of the best technical turbo posts I have read in a long time!