Precision Billet wheel 67mm turbo vs cast wheel results!

Should be a techy thread so I will put this here as a follow up to the install of the new billet turbo thread.
http://www.s197forum.com/forum/showthread.php?t=43665&highlight=turbo

Got out to the dyno today at Mid Atlantic Performance in Richmond and let Mike Rousch work his magic. Had to get the tune tweaked for the new turbo and the driveability issues fixed.(last time i was on the dyno i had bad 02 sensors.)

Old turbo was Precsion cast wheel 67mm. And the new turbo is the same 67mm size with a billet wheel.

So, first off backed off the boost controller to get the boost back down(at the same boost controller setting the new turbo was making 2-3 more psi) New street tune at 11.6 psi 550rwhp 510rwtq only pulled to 6000rpms would have made a little more power if we spun it higher, but no need, a/f was good and we wanted to turn up the boost.
(old turbo made 563rwhp 516rwtq at 12.1 psi reving to 6500, so similar numbers)

Next were the shocking results!!! Bumped it up a few psi with the boost controller and at 14.6 psi made basicly the same power numbers up top at the exact same boost level as the old turbo.(old turbo 603rwhp , new turbo 605 rwhp) So we overlayed the old cast turbo pull and the new billet turbo pull and we were shocked! At 3800 rpms the billet turbo was up 130rwhp and 141rwtq! Huge gain in midrange and spool! From the start of the pull from 2,000 rpms the billet turbo is already up 30hp/tq and just climbs from there!


Old vs new peak numbers (603 is old, 605 is new)


Old turbo 14.6psi pull in green, new turbo 14.6 psi pull in red. (from 5,000 rpms and up the graphs even out, but from 2,000 rpms to 5,000 rpms the billet turbo is murdering the cast turbo in power and torque output!)
At 3800 rpms the billet turbo was up 130rwhp and 141rwtq!



Badass!, why not crank it up a lil more? lol added another 10% to the boost controller duty cycle and made 16 psi, final numbers 655rwhp 582rwtq!




Called it a day there! Thats about the most boost/power I want to run on pump gas (93 octane.)

Great job Jeremy, good talking to you and Greg today. Guy's Jermey did quality work putting together his turbo system and really deserves the rewards.


Earl

Very nice work! Must sure feel REALLY nice in the mid range now!

Nice numbers

Sick!

Send me your email address and I will email you the dyno pics I took on my phone.

That's a real nice increase in power in the midrange, looks like the billet wheel was worth it. I bet traction is even worse now, lol.

retfr8flyr said:

Great job Jeremy, good talking to you and Greg today. Guy's Jermey did quality work putting together his turbo system and really deserves the rewards.


Earl

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Thanks Earl!

GB10 said:

That's a real nice increase in power in the midrange, looks like the billet wheel was worth it. I bet traction is even worse now, lol.

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Haha, yeah i could feel the low to mid power increase immediately on the street before i even got these results, its nice to see I was right. And yeah thats why I have dr's and can lower the boost lol. It hits hard!

Congrats on the results.

I ordered my billet 6765 dual bearing E compressor turbo last week and its scheduled to arrive on Monday. There are no compressor maps out there for this turbo so I was a bit worried as to how the 4.6 would react to it, but it seems to work great.

What A/R did you go with on the turbine? I ended up getting the .82.

I'm definitely excited now.

Goose said:

Congrats on the results.

I ordered my billet 6765 dual bearing E compressor turbo last week and its scheduled to arrive on Monday. There are no compressor maps out there for this turbo so I was a bit worried as to how the 4.6 would react to it, but it seems to work great.

What A/R did you go with on the turbine? I ended up getting the .82.

I'm definitely excited now.

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You will love it. I we have the same size E compressor cover. Its a t4 with
3" vband outlet .68 ar. I was torn between .81 and .68. I was worried I might loose alittle top end with the .68, but I obviously did not. This turbo is everything I thought it would be and more.

Awesome results! Congrats! Can't wait to see time slips!!

How much of that gain was due to the smaller a/r housing on the new turbo?

Great numbers Jeremy! Now I really am ready to get my build going.

white05gt said:

How much of that gain was due to the smaller a/r housing on the new turbo?

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+1

in your other thread, you posted that you had a .81ar, and went down to a .68, logically, your mid range would increase significantly and top stay the same. too bad you weren't able to test a cast wheel at .68ar, i'll bet you have almost similar results.
i'm not sold on the billet wheel, the cost is outrageous....for those who don't have hookups, haha.

edit: i may be wrong tho...

nice ride btw, wish i was boosted, haha

Do know or have theories as to where the HP gains came from ? Are you saying the billet impeller spooled faster ? I would be interested to see the boost curves between the 2 Turbos, at same boost levels you are not going to pick up 130RWHP without changing the tune. I am far from being a expert but the little that I do know makes me believe it came from the ar change.

Either way, it must be nice to even have boost at 2000rpm and your numbers are very impressive

white05gt said:

How much of that gain was due to the smaller a/r housing on the new turbo?

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None, if anything it would have hurt power output. Although Im glad it didn't! I had a .96 originaly and then stepped down to a .81 ( saw/felt no noticeable change/gain) so going down one more size from .81 to .68 ar size maybe helped initial spool a couple hundred rpm on a t4 config. One eye willy did extensive testing on .96, .81, and .68 housings and found very little diffrence in spool/power from .68 to .81. My buddy told me to get .68 and my gut said .81, so I went off his advice and im glad i didnt loose any peak power, at least i didnt at 14psi anyway, the billet wheel really helped that. I still think .81 is going ot be best for my setup with max power goals of 650-700rwhp so i will likely change it back to .81 down the line.

Mr. Q said:

+1

in your other thread, you posted that you had a .81ar, and went down to a .68, logically, your mid range would increase significantly and top stay the same. too bad you weren't able to test a cast wheel at .68ar, i'll bet you have almost similar results.
i'm not sold on the billet wheel, the cost is outrageous....for those who don't have hookups, haha.

edit: i may be wrong tho...

nice ride btw, wish i was boosted, haha

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Nope, not logically lol, ar housing size does not effect compressor map effieceny range. A smaller housing will bring on initial spool a little sooner but hurt max flow/hp up top and vice versa. (were talking 200-300rpms heres). Ar housing size is more critical on small dispalcement high boost motors. On a 4 banger an ar size change can be a diffrence of 500+rpms in initial spool. but on our cars were talking 100-300rpms, almost negligible. And this is just initial spool rpm. I didnt shift my power band a couple hundred rpm to the right, i completely changed it! And thanks man the car is a blast to drive!

Buzz Lightyear said:

Do know or have theories as to where the HP gains came from ? Are you saying the billet impeller spooled faster ? I would be interested to see the boost curves between the 2 Turbos, at same boost levels you are not going to pick up 130RWHP without changing the tune. I am far from being a expert but the little that I do know makes me believe it came from the ar change.

Either way, it must be nice to even have boost at 2000rpm and your numbers are very impressive

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No theories here, Compressor map, compressor map, compressor map! Its not just a billet wheel turbo(yes it is a one piece ie billet design, but thats not where the gain is from) its a completely different impeller design. With a completely different compressor map/efficiency range compare to the cast wheel design. The billet wheel boasts the midrange of a much smaller turbo wheel with the max power range of a much bigger turbo wheel, the best of both worlds. Ar housing has really nothing to do with the efficiency range of a turbo. AR size is important to match up for the size/displacement of the engine and the max/boost power you intend to run as i stated above.

Maybe post pics of the different impeller designs in this thread for those in doubt. Lightblade posted in another thread and there are significant differences between the two wheels; it's not just that one is made from billet and the other is cast.

GB10 said:

Maybe post pics of the different impeller designs in this thread for those in doubt. Lightblade posted in another thread and there are significant differences between the two wheels; it's not just that one is made from billet and the other is cast.

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Yeap here they are.

Cast wheel design on left, Billet wheel design on right.


Close ups



And an internet pic I found comparing the different impeller designs.

Lightblade said:

Ar housing has really nothing to do with the efficiency range of a turbo. AR size is important to match up for the size/displacement of the engine and the max/boost power you intend to run as i stated above.

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Wrong..... AR has everything to do with the efficiency, smaller AR compressor spools much faster and less lag. It might only be a difference of 200-300rpm on when boost initially comes on but the difference between what RPM you see full boost will be much sooner that that 200-300 RPM on the big end. Also a smaller AR at big end will will have more back pressure than a larger. The larger AR will have a slower spool up but will make more power up top. I realize that in your case you didnt see it but I would venture to guess it would be seen by turning up the boost.

Dont take my word for it,

http://www.turbobygarrett.com/turbobygarrett/tech_center/turbo_tech102.html

Do you have a datalog of the before and after boost curves ? All things equal, its impossible to pick up 130RWHP at same RPM without changing the tune, increasing boost or cooling the intake charge. Im not looking to destroy your thread and this will be my last post on the subject.


As stated before, the end results are very impressive and I bet its fun to drive.

Congrats

Buzz Lightyear said:

Wrong..... AR has everything to do with the efficiency, smaller AR compressor spools much faster and less lag. It might only be a difference of 200-300rpm on when boost initially comes on but the difference between what RPM you see full boost will be much sooner that that 200-300 RPM on the big end. Also a smaller AR at big end will will have more back pressure than a larger. The larger AR will have a slower spool up but will make more power up top. I realize that in your case you didnt see it but I would venture to guess it would be seen by turning up the boost.

Dont take my word for it,

http://www.turbobygarrett.com/turbobygarrett/tech_center/turbo_tech102.html lol

Do you have a datalog of the before and after boost curves ? All things equal, its impossible to pick up 130RWHP at same RPM without changing the tune, increasing boost or cooling the intake charge. Im not looking to destroy your thread and this will be my last post on the subject.


As stated before, the end results are very impressive and I bet its fun to drive.

Congrats

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Sorry man, you are way off. Your are mis-interpreting, ar exhuast housing size will not effect the compressor wheels efficency range (compressor map). It will just start turning it a little faster, sooner, and in turn have more back pressure which will slow it down a little up top as well.

A turbo's efficency has to do with the compressor wheel design, the ar housing on the turbine wheel is just a small part and is more important to match to your setup, ie exhuast flow.

Shit if it were that easy we could make $200 dollar ebay turbos work wonders with just an ar housing swap.


I will quote directly from your link so you can re-read it.



Turbine ar size has to do with performance, ie spool rpm and peak power, not compressor effiecency, two totaly different things!