Garrett vs Precision turbos for 944/968
06-29-2011, 03:47 PM
#1
Garrett vs Precision turbos for 944/968
Before starting a war between what is better I'm going to specify what I had, what I was looking for and what eventually happened.
As you already know I have a 3.2lt 4valve 968 engine with variocam and TEC 3 ems. The car had an old Garrett 60-1 T04 .68 a/r exhaust. With this set up the engine was making over 500 rwhp at 16psi.
I decided that since the turbo was of an old design to look into new turbo designs like ball bearing and billet wheels to improve the turbo spool up. I just wanted to improve the responsiveness of the engine at low rpms without loosing hp.
I ended up having to decide between going with the same Garrett turbo but with BB or switching to a Precision turbo with billet and BB which seems to be the hot ticket on the import world right now.
I ended up going the Precision route and was directed by Precision to buy a billett 6265 with a .68 a/r hot side. They assured me this setup will provide me with better spool up and the same hp. They said that for a 6262 will give me better yet spool up but will not support the hp numbers the engine was producing with the old turbo.
After installation and dyno setup of the ems I ended up with about the same hp as before and the engine felt flat down low the rpms. I was having to down shift a lot just to get the engine to produce tq(due mostly to the lower gearing) which before was not happening. I talked to Precision about this experience and was told they could not understand why this was happening and suggested to switch to a .58 a/r as a way of improving spool up by 200rpms.
I did tell them that I believed 200rpms will not have a big effect on how flat the engine felt and that I though that a 6262 might work better for the strong low rpm spool up I was looking. They indicated that a 6262 will not be able to produce the kind of hp I had. Then I suggested a 5865 or 6065. They responded that they will not make a 5865 and the "Billet" 6065 was discontinued.
By this time it became very clear that these research and development will have to be subsidized by my pocket and Precision will not help if all this trial and error did not work. Also replacing turbos on our cars take hours to do plus retuning of the ems plus all the tear and wear of bolts and parts being loosened and tightened time after time.
I decided to stick to what I knew worked. Ordered the Garrett 60-1 T04 BB .68 hot, installed, retuned and got all the tq back and could not be happier.
So it might be that Precision turbos work. I just was not in the mood to be the one spending the thousands of dollars plus my time and effort to find out which set up was the right one for my low boost(19.5psi max/daily 13psi); low rpms 6800 max application, specially since I had a set up that was working perfectly and I could attain my objective by switching to BB.
Precision people know a lot about Japan imports with their high boost/rpms setups. They know squat about 944/968 low boost/rpms.
Remember: Bigger is not always better. Just my experience and opinions.
As you already know I have a 3.2lt 4valve 968 engine with variocam and TEC 3 ems. The car had an old Garrett 60-1 T04 .68 a/r exhaust. With this set up the engine was making over 500 rwhp at 16psi.
I decided that since the turbo was of an old design to look into new turbo designs like ball bearing and billet wheels to improve the turbo spool up. I just wanted to improve the responsiveness of the engine at low rpms without loosing hp.
I ended up having to decide between going with the same Garrett turbo but with BB or switching to a Precision turbo with billet and BB which seems to be the hot ticket on the import world right now.
I ended up going the Precision route and was directed by Precision to buy a billett 6265 with a .68 a/r hot side. They assured me this setup will provide me with better spool up and the same hp. They said that for a 6262 will give me better yet spool up but will not support the hp numbers the engine was producing with the old turbo.
After installation and dyno setup of the ems I ended up with about the same hp as before and the engine felt flat down low the rpms. I was having to down shift a lot just to get the engine to produce tq(due mostly to the lower gearing) which before was not happening. I talked to Precision about this experience and was told they could not understand why this was happening and suggested to switch to a .58 a/r as a way of improving spool up by 200rpms.
I did tell them that I believed 200rpms will not have a big effect on how flat the engine felt and that I though that a 6262 might work better for the strong low rpm spool up I was looking. They indicated that a 6262 will not be able to produce the kind of hp I had. Then I suggested a 5865 or 6065. They responded that they will not make a 5865 and the "Billet" 6065 was discontinued.
By this time it became very clear that these research and development will have to be subsidized by my pocket and Precision will not help if all this trial and error did not work. Also replacing turbos on our cars take hours to do plus retuning of the ems plus all the tear and wear of bolts and parts being loosened and tightened time after time.
I decided to stick to what I knew worked. Ordered the Garrett 60-1 T04 BB .68 hot, installed, retuned and got all the tq back and could not be happier.
So it might be that Precision turbos work. I just was not in the mood to be the one spending the thousands of dollars plus my time and effort to find out which set up was the right one for my low boost(19.5psi max/daily 13psi); low rpms 6800 max application, specially since I had a set up that was working perfectly and I could attain my objective by switching to BB.
Precision people know a lot about Japan imports with their high boost/rpms setups. They know squat about 944/968 low boost/rpms.
Remember: Bigger is not always better. Just my experience and opinions.
Last edited by zagaone; 06-29-2011 at 04:46 PM.
06-29-2011, 04:23 PM
#3
Drifting
Angel,
I'm using a Billett Precision 6262 BB with a .58 on my 3.1 and we are getting boost at tip in. By 3K we are seeing over 10lbs and well before 4K it's at whatever the boost controller is set. We are still tuning, and expect to see slightly better spool up when we begin to advance the timing more.
We did have Precision build this turbo for this motor based on our intake, intercooler, hp and spool requirements, and response. This may have something to do with the results. Garrity sent them our flow chart expectations, and they built this particular unit. Garrity has been in the Porsche game for longer than most. He was building deck plates when many of the listers were in diapers.
Garrity built this motor, and I sent him your videos.
Precision also builds turbos for http://www.horsepowerfreaks.com/part...s/E46_M3/11037.
No wars. I think EVERY top modern turbo manufacturer turbos will work well on our cars. Most share components in one way or another. The issue is getting it right when they have never done any R&D using our particular motors. There aren't enough of our cars out there to justify spending the money. Some of the best 2.5 cars I've owned used old school KKK turbos.
I'm glad you are happy with your car. It's the only thing that matters.
I'm using a Billett Precision 6262 BB with a .58 on my 3.1 and we are getting boost at tip in. By 3K we are seeing over 10lbs and well before 4K it's at whatever the boost controller is set. We are still tuning, and expect to see slightly better spool up when we begin to advance the timing more.
We did have Precision build this turbo for this motor based on our intake, intercooler, hp and spool requirements, and response. This may have something to do with the results. Garrity sent them our flow chart expectations, and they built this particular unit. Garrity has been in the Porsche game for longer than most. He was building deck plates when many of the listers were in diapers.
Garrity built this motor, and I sent him your videos.
Precision also builds turbos for http://www.horsepowerfreaks.com/part...s/E46_M3/11037.
No wars. I think EVERY top modern turbo manufacturer turbos will work well on our cars. Most share components in one way or another. The issue is getting it right when they have never done any R&D using our particular motors. There aren't enough of our cars out there to justify spending the money. Some of the best 2.5 cars I've owned used old school KKK turbos.
I'm glad you are happy with your car. It's the only thing that matters.
06-29-2011, 04:47 PM
#5
Burning Brakes
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That has nothing to do withe manufacterer, Modern turbos require boost and rpm. Somebody did the home work on his old choice, it is unlikely that they picked the turbo off the shelf, .It requires R&D to make a turbo work and the threadstarter was unwilling to do that. I would have tried meth first before taking the unit off and up the boost/rpm, afterall he has a 16 valve head and go from there.
In my experience ballbearing does not improve spool but enhances reliability and longevity.
In my experience ballbearing does not improve spool but enhances reliability and longevity.
06-29-2011, 04:48 PM
#6
Race Car
To be clear these are all T4 inlets correct?
I have swapped so many turbos on my car that it makes my head spin. I think what you are experiencing is a difference in transient flow. I am not familiar with precision however I have experienced similar issues with using smaller inducer compressors vs larger inducted and felt like you have in regards to low rpm response.
Looking at most compressor maps it appears you have pretty much the perfect turbo for a low boost larger ci engine. You probably would not make any more power with added boost with your current turbo.
In my quest for more power I have come to the conclusion that unless I want to have a laggy high revving car I have to settle for my current unit or switch to a gt30. Or build a bigger engine and use the hx40 super or gt35.
It's a balancing act, and it appears you have found the perfect balance!!
I have swapped so many turbos on my car that it makes my head spin. I think what you are experiencing is a difference in transient flow. I am not familiar with precision however I have experienced similar issues with using smaller inducer compressors vs larger inducted and felt like you have in regards to low rpm response.
Looking at most compressor maps it appears you have pretty much the perfect turbo for a low boost larger ci engine. You probably would not make any more power with added boost with your current turbo.
In my quest for more power I have come to the conclusion that unless I want to have a laggy high revving car I have to settle for my current unit or switch to a gt30. Or build a bigger engine and use the hx40 super or gt35.
It's a balancing act, and it appears you have found the perfect balance!!
06-29-2011, 04:51 PM
#7
Drifting
http://www.horsepowerfreaks.com/prod...isionTurbo.asp
A friend has the stage 2 kit on his M3. Fast, fun car. Like I stated earlier, all modern turbo manufacturers can make their turbos work well on any car. If they know what you want out of your motor, and they are dealing with a vendor that can potentially sell hundreds of their turbos, you are likely to get close to exactly what you want.
If you aren't doing a custom motor/car, stick with what has been proven. Many of the vendors on this list are your best choice. They have done the R&D and know what will work best on your particular needs.
Like I stated earlier, I used to have a 2.5 951 that dynoed 345wt and 330whp at 19psi boost. The 345wt was at 3500RPM and max hp was at 6600rpm. This was done in 1999 at Technodyne in Phoenix. I have the chart at home. This was a very easy car to drive well and it was fast. Really a bad *** 951 considering this was done on a completely stock bottom end 2.5 motor.
A friend has the stage 2 kit on his M3. Fast, fun car. Like I stated earlier, all modern turbo manufacturers can make their turbos work well on any car. If they know what you want out of your motor, and they are dealing with a vendor that can potentially sell hundreds of their turbos, you are likely to get close to exactly what you want.
If you aren't doing a custom motor/car, stick with what has been proven. Many of the vendors on this list are your best choice. They have done the R&D and know what will work best on your particular needs.
Like I stated earlier, I used to have a 2.5 951 that dynoed 345wt and 330whp at 19psi boost. The 345wt was at 3500RPM and max hp was at 6600rpm. This was done in 1999 at Technodyne in Phoenix. I have the chart at home. This was a very easy car to drive well and it was fast. Really a bad *** 951 considering this was done on a completely stock bottom end 2.5 motor.
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06-29-2011, 04:53 PM
#8
Drifting
06-29-2011, 05:33 PM
#9
I'm refering to T4.
I believe that Precision is concentrating in the high boost/rpm import market and it shows in them not offering small billet inducer compressors with their big turbines.
A BB billet 5865 with .68 a/r or a 6065 .68 a/r will be great turbos for bigger than 3.0lt low boost/rpms engines. That kind of turbo will provide quick response from the smaller inducer (58/60) and still provide high hp from a lot of turbine flow from the 65 turbine.
The different results I got might have been from the difference on compressor wheel size or it might be related to the wheels (Compressor and Turbine) designs. Who knows. I decided not to find out. Too expensive and time consuming with no real necessity or motivation.
My Garrett is a basic 60-1 with .70 a/r; 58.7mm inducer compressor and a regular P-trim turbine, .68a/r. The inducer is a lot smaller diameter than the Precision 6265, but the turbines were exactly the same sizes and trim but different design. The Garrett has 11 thin fins to the Precision thicker 10 fins.
With that "small turbo" the engine got at my last dyno session with a new Profec B series II evc the following:
13psi: 483rwhp
16 psi: 512rwhp
18 psi: 533rwhp
19.5 psi: 551rwhp
And the Hp was still climbing(although barelly) at the 6,800 cut off. Due to lubrication design issues with these type of engine blocks anything beyond 7000rpm should be avoided for sustained periods of operation, so increasing the rpm range is out of the question. And from personal experience I decided to not go higher than 19 psi. Daily usage I am at 13psi with evc off or 15 with evc on Lo setting.
George I'm curious in finding out what the hp capabilities of the 6262 are, specially in the 16-19 psi range. Let us know what you get.
I believe that Precision is concentrating in the high boost/rpm import market and it shows in them not offering small billet inducer compressors with their big turbines.
A BB billet 5865 with .68 a/r or a 6065 .68 a/r will be great turbos for bigger than 3.0lt low boost/rpms engines. That kind of turbo will provide quick response from the smaller inducer (58/60) and still provide high hp from a lot of turbine flow from the 65 turbine.
The different results I got might have been from the difference on compressor wheel size or it might be related to the wheels (Compressor and Turbine) designs. Who knows. I decided not to find out. Too expensive and time consuming with no real necessity or motivation.
My Garrett is a basic 60-1 with .70 a/r; 58.7mm inducer compressor and a regular P-trim turbine, .68a/r. The inducer is a lot smaller diameter than the Precision 6265, but the turbines were exactly the same sizes and trim but different design. The Garrett has 11 thin fins to the Precision thicker 10 fins.
With that "small turbo" the engine got at my last dyno session with a new Profec B series II evc the following:
13psi: 483rwhp
16 psi: 512rwhp
18 psi: 533rwhp
19.5 psi: 551rwhp
And the Hp was still climbing(although barelly) at the 6,800 cut off. Due to lubrication design issues with these type of engine blocks anything beyond 7000rpm should be avoided for sustained periods of operation, so increasing the rpm range is out of the question. And from personal experience I decided to not go higher than 19 psi. Daily usage I am at 13psi with evc off or 15 with evc on Lo setting.
George I'm curious in finding out what the hp capabilities of the 6262 are, specially in the 16-19 psi range. Let us know what you get.
06-29-2011, 06:41 PM
#11
I would like a good bolt in turbo for a 951 that spooled like a modern turbo does. Almost instant spool up, like 2000 RPM its starting to build a little boost, and then full boost by 3,000 RPM.
06-29-2011, 06:59 PM
#12
Rennlist Member
I have been looking a lot at the Garrett T3/T4R dual ball bearing unit with 50 trim, TO4E, #8 KKK replica housing. Nize had a thread about this a few years ago. This turbo looks like it plays the balancing act pretty well, great spool up and good top end power for the street.
06-29-2011, 07:35 PM
#13
Drifting
Sean has a Tial unit on his 2.5. Spools very quickly. His car feels like it has full boost by 3K in the higher gears at speed.
06-29-2011, 10:42 PM
#14
Race Car
I have been looking a lot at the Garrett T3/T4R dual ball bearing unit with 50 trim, TO4E, #8 KKK replica housing. Nize had a thread about this a few years ago. This turbo looks like it plays the balancing act pretty well, great spool up and good top end power for the street.
