Pettit Super Charger Owners
#3576
whines all the way home
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Both are pretty smooth with nice power coming on quicker than the feel in an NA , the TC car Ive been in I would describe as a little bit more raw in that when it hit boost it kicked ya in the but, the SC that we drive in here has that warp drive feel with the power feeling coming higher in the RPM range, I would say the TC gives you a torqier feeling,,,
Sorry I got distacted in your other thread by someone trying to describe the feeling without being in either,,,
Sorry I got distacted in your other thread by someone trying to describe the feeling without being in either,,,
#3577
Rotary , eh?
iTrader: (1)
You can run ~13psi of boost on a MP90 for the 6 port engine and still be within Eaton's redline. That GT500 unit is most likely a 112. Either way, dimensions and snout on that GT500 unit would be difficult to package under the hood.
My guess is install an external oil tap for the current Autorotor units you guys have and spin the current unit to get to StageIII levels. The efficiency would probably be about the same as is on MP series from Eaton.
My guess is install an external oil tap for the current Autorotor units you guys have and spin the current unit to get to StageIII levels. The efficiency would probably be about the same as is on MP series from Eaton.
you and your fancy "books". get a clue buddy.
#3578
Londons Yellow Peril
yeah I've been in a couple of Turbo 8s and a couple of Pettit SC ones.
On a track day I was driving a SC car and rode in a Greddy turbo one.
The Greddy install was hell though with heat soak making it like driving in a sauna! I actually felt sick after 2 laps.
The Greddy owner rode in mine and said he felt it was pulling better than his car, but without longer comparisons actually driving the cars, I cant say much more. He said he lost power quickly due to heat issues.
I do love my SC car though, in my opinion it's like a perfect RX8 now!
Unfortunately, someone rear ended me, so its in the garage, and I'm missing it a lot!!!! BOOO!
On a track day I was driving a SC car and rode in a Greddy turbo one.
The Greddy install was hell though with heat soak making it like driving in a sauna! I actually felt sick after 2 laps.
The Greddy owner rode in mine and said he felt it was pulling better than his car, but without longer comparisons actually driving the cars, I cant say much more. He said he lost power quickly due to heat issues.
I do love my SC car though, in my opinion it's like a perfect RX8 now!
Unfortunately, someone rear ended me, so its in the garage, and I'm missing it a lot!!!! BOOO!
#3579
Registered
Asked this in a SC vs turbo thread bit didn't get a real answer. Hoping you guys can offer your perspective.
I've seen all of the charts and have read a fair amount about both SC and Turbo options but have not driven either (none avail in my area). Would like some perspective from those that have actually driven both. Looking for "driveability and feel" differences for a DD. I assume that the numbers only tell part of the story. Please tell me the rest. How is the Petit SC experience different than the turbo experience on the road and track? Thx
I've seen all of the charts and have read a fair amount about both SC and Turbo options but have not driven either (none avail in my area). Would like some perspective from those that have actually driven both. Looking for "driveability and feel" differences for a DD. I assume that the numbers only tell part of the story. Please tell me the rest. How is the Petit SC experience different than the turbo experience on the road and track? Thx
This means it moves from the low end of the curve to the high end very easily.
And the "SC takes 30 to 40 HP"; two things to remember:
(I think some people already knew them too)
The Lysholm blower is a small twisted screw type, running close to it's sweet spot for efficiency, not the large 8-71 Roots type blower used for your "30 to 40 HP" calculation.
I expect the Pettit blower to draw less than 15 to 20 HP, even when spinning under load at 16,000 RPM.
The bypass valve opens when the engine does not need boost, when fully open, the S/C is free from load uses less than 3/4 HP to turn the screws.
There is no free lunch with boost verses sacrificial power loss, a theoretical Turbonique style "rocket powered" turbo configuration, to completely remove the exhaust restriction caused by the turbo's impeller, would get back more than "6 to 10" HP. (Turbonique was awesome in the early 60s)
As for which is better; S/C or Turbo?
I say, boosted is better than N/A any day.
Last edited by Rote8; 11-19-2008 at 07:11 AM.
#3580
Registered
I hope everyone had anti-freeze in any liquid to air inter coolers last night.
I forgot; I had to remove some water, add anti-freeze and recirculate for 20 minutes after dark last night.
I forgot; I had to remove some water, add anti-freeze and recirculate for 20 minutes after dark last night.
#3581
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That is pretty late, but that is also a characteristic of the S/C. It pushes more air on RPM, rather than engine demand. Compare the torque curves for a visual on that.
What do you mean "read"?
That is what it uses at peak load, minimum. It is probably closer to 50 in this application. It pulls nearly 1.5 HP at idle!
That is why you see roughly equivalent net power between the turbo and the S/C with such a wide airflow discrepancy.
The 6 - 10 HP the turbo takes out of the net power is already built into the metered airflow.
What do you mean "read"?
That is what it uses at peak load, minimum. It is probably closer to 50 in this application. It pulls nearly 1.5 HP at idle!
That is why you see roughly equivalent net power between the turbo and the S/C with such a wide airflow discrepancy.
The 6 - 10 HP the turbo takes out of the net power is already built into the metered airflow.
Last edited by morkusyambo; 11-19-2008 at 09:43 AM.
#3582
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The S/C torque curve is flat, almost a table top.
This means it moves from the low end of the curve to the high end very easily.
And the "SC takes 30 to 40 HP"; two things to remember:
(I think some people already knew them too)
The Lysholm blower is a small twisted screw type, running close to it's sweet spot for efficiency, not the large 8-71 Roots type blower used for your "30 to 40 HP" calculation.
I expect the Pettit blower to draw less than 15 to 20 HP, even when spinning under load at 16,000 RPM.
The bypass valve opens when the engine does not need boost, when fully open, the S/C is free from load uses less than 3/4 HP to turn the screws.
There is no free lunch with boost verses sacrificial power loss, a theoretical Turbonique style "rocket powered" turbo configuration, to completely remove the exhaust restriction caused by the turbo's impeller, would get back more than "6 to 10" HP. (Turbonique was awesome in the early 60s)
As for which is better; S/C or Turbo?
I say, boosted is better than N/A any day.
This means it moves from the low end of the curve to the high end very easily.
And the "SC takes 30 to 40 HP"; two things to remember:
(I think some people already knew them too)
The Lysholm blower is a small twisted screw type, running close to it's sweet spot for efficiency, not the large 8-71 Roots type blower used for your "30 to 40 HP" calculation.
I expect the Pettit blower to draw less than 15 to 20 HP, even when spinning under load at 16,000 RPM.
The bypass valve opens when the engine does not need boost, when fully open, the S/C is free from load uses less than 3/4 HP to turn the screws.
There is no free lunch with boost verses sacrificial power loss, a theoretical Turbonique style "rocket powered" turbo configuration, to completely remove the exhaust restriction caused by the turbo's impeller, would get back more than "6 to 10" HP. (Turbonique was awesome in the early 60s)
As for which is better; S/C or Turbo?
I say, boosted is better than N/A any day.
Now, rx8thunder, please keep the TC vs. SC conversation in its proper thread. It has been done to death over here.
Thanks. -Yambo.
#3583
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#3587
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on track the s.c. can get great performance with a adverage lower rpm . i rarely go over 7.5K on the car. less rpm's means less heat which is good for all. Also less strain on drivetrain. It suits me fine--turbo's are great just a little differant animal.
You would have to set the boost properly so the power delivery would be smooth
"power "kicks" on the track is not a good idea.
OD
You would have to set the boost properly so the power delivery would be smooth
"power "kicks" on the track is not a good idea.
OD
#3588
Boosted Kiwi
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Tend to agree with you about the power "kick" being a bad thing on the track with a turbo. I'll be starting my learning curve on that next week .
As far as heat soak mentioned above goes i think that would come down to how the turbo is set up . I am thinking a lot of early turbo users ran at lower pressures and high rpm which is counter productive for heat soak issues as it puts the turbo well outside its efficiency curve . (yes- i just learned this)
As far as heat soak mentioned above goes i think that would come down to how the turbo is set up . I am thinking a lot of early turbo users ran at lower pressures and high rpm which is counter productive for heat soak issues as it puts the turbo well outside its efficiency curve . (yes- i just learned this)
#3589
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#3591
Being (new) single rocks!
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Thanks for the feedback guys. I do get that there is no perfect option. I am very encouraged about what I hear about the SC in terms of it's unique characteristics. I also found this post on Yahoo! interesting...
"Either choice is good depending on how you want to change the engine characteristics.
Turbo's can give the Renesis more overall HP and torque, but the power will be "peaky". You will gain little in the lower RPM band, have a huge spike of power in the middle band, and then die off around 6500 - 7000 RPM. This is because the turbo won't respond and give any appreciable boost until 3K - 4K RPM...completely normal for a turbo. Then the turbo will be able to create large airflow, but only up to perhaps 6K RPM where it will be producing its maximum flow. Then power drops off as you have the same airmass but the higher RPM's mean less shared air available per combustion cycle.
This is too bad as the motor runs to 9K+ RPM and the tertiary intake ports don't even open until 7200 RPM.
You can get turbo's that can flow enough air to allow proper chamber filling at the higher RPM's, but they'll take longer to respond and boost may not appear until 5-6K RPM.
The superchargers designed for the RX8 have been designed with the extended RPM range of the Renesis in mind. You'll have a better low end as they produce boost all the time, just not as much low down as it's not spinning as fast, and the airflow can keep increasing with RPM right up to 9K. But you won't get as much mid-range power as the turbo as boost & airmass is related to RPM.
So the turbo will give you more total HP, mainly in the middle RPM band and change the way power is delivered. The SC will give a lower overall power increase, but it will be distributed more evenly across the RPM band and the motor's response will feel much the same as now, just with more grunt everywhere."
"Either choice is good depending on how you want to change the engine characteristics.
Turbo's can give the Renesis more overall HP and torque, but the power will be "peaky". You will gain little in the lower RPM band, have a huge spike of power in the middle band, and then die off around 6500 - 7000 RPM. This is because the turbo won't respond and give any appreciable boost until 3K - 4K RPM...completely normal for a turbo. Then the turbo will be able to create large airflow, but only up to perhaps 6K RPM where it will be producing its maximum flow. Then power drops off as you have the same airmass but the higher RPM's mean less shared air available per combustion cycle.
This is too bad as the motor runs to 9K+ RPM and the tertiary intake ports don't even open until 7200 RPM.
You can get turbo's that can flow enough air to allow proper chamber filling at the higher RPM's, but they'll take longer to respond and boost may not appear until 5-6K RPM.
The superchargers designed for the RX8 have been designed with the extended RPM range of the Renesis in mind. You'll have a better low end as they produce boost all the time, just not as much low down as it's not spinning as fast, and the airflow can keep increasing with RPM right up to 9K. But you won't get as much mid-range power as the turbo as boost & airmass is related to RPM.
So the turbo will give you more total HP, mainly in the middle RPM band and change the way power is delivered. The SC will give a lower overall power increase, but it will be distributed more evenly across the RPM band and the motor's response will feel much the same as now, just with more grunt everywhere."
#3592
Illudium Q-36 Space Moderator
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That information is actually incorrect - but whatever.
If you are leaning SC; then go with it - I bet you will be perfectly happy.
If you are leaning turbo; get the right size and go with it - I bet you will be perfectly happy.
If you think one is superior to another - great; go with it...
If you want to know more about Forced Induction; then do the legwork. But honestly for a street driven car; within +-30 HP; I bet they feel pretty much the same.
If you are leaning SC; then go with it - I bet you will be perfectly happy.
If you are leaning turbo; get the right size and go with it - I bet you will be perfectly happy.
If you think one is superior to another - great; go with it...
If you want to know more about Forced Induction; then do the legwork. But honestly for a street driven car; within +-30 HP; I bet they feel pretty much the same.
#3593
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#3594
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That information is actually incorrect - but whatever.
If you are leaning SC; then go with it - I bet you will be perfectly happy.
If you are leaning turbo; get the right size and go with it - I bet you will be perfectly happy.
If you think one is superior to another - great; go with it...
If you want to know more about Forced Induction; then do the legwork. But honestly for a street driven car; within +-30 HP; I bet they feel pretty much the same.
If you are leaning SC; then go with it - I bet you will be perfectly happy.
If you are leaning turbo; get the right size and go with it - I bet you will be perfectly happy.
If you think one is superior to another - great; go with it...
If you want to know more about Forced Induction; then do the legwork. But honestly for a street driven car; within +-30 HP; I bet they feel pretty much the same.
-Yambo
#3596
That is pretty late, but that is also a characteristic of the S/C. It pushes more air on RPM, rather than engine demand. Compare the torque curves for a visual on that.
What do you mean "read"?
That is what it uses at peak load, minimum. It is probably closer to 50 in this application. It pulls nearly 1.5 HP at idle!
That is why you see roughly equivalent net power between the turbo and the S/C with such a wide airflow discrepancy.
The 6 - 10 HP the turbo takes out of the net power is already built into the metered airflow.
What do you mean "read"?
That is what it uses at peak load, minimum. It is probably closer to 50 in this application. It pulls nearly 1.5 HP at idle!
That is why you see roughly equivalent net power between the turbo and the S/C with such a wide airflow discrepancy.
The 6 - 10 HP the turbo takes out of the net power is already built into the metered airflow.
#3597
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I have documentation on Lysholm units. They typically draw 5hp more than the Autorotor ones. Off the top of my head the RX-8 draw from Lysholm was around 30hp at 8psi.
#3599
Illudium Q-36 Space Moderator
iTrader: (1)
Do Until [Tired of BS] = "yes"
Call SC_is_mo_better_science()
If Postcount On Subject < 100 Then [Tired of BS] = "no" Else [Tired of BS] = "yes" End If
Call TC_is_mo_better_science()
If Postcount On Subject < 100 Then [Tired of BS] = "no" Else [Tired of BS] = "yes" End If
Call not_ugh()
If Postcount On Subject < 100 Then [Tired of BS] = "no" Else [Tired of BS] = "yes" End If
Call uhh_huh()
If Postcount On Subject < 100 Then [Tired of BS] = "no" Else [Tired of BS] = "yes" End If
Call various_dyno_proof()
If Postcount On Subject < 100 Then [Tired of BS] = "no" Else [Tired of BS] = "yes" End If
Call various_dyno_rebuttals()
If Postcount On Subject < 100 Then [Tired of BS] = "no" Else [Tired of BS] = "yes" End If
Call circular_logic()
If Postcount On Subject < 100 Then [Tired of BS] = "no" Else [Tired of BS] = "yes" End If
Call other_poster_is_a_poo_poo_head_and_fanboi()
If Postcount On Subject < 100 Then [Tired of BS] = "no" Else [Tired of BS] = "yes" End If
Loop
There - just run this little program to find out what happens.
Call SC_is_mo_better_science()
If Postcount On Subject < 100 Then [Tired of BS] = "no" Else [Tired of BS] = "yes" End If
Call TC_is_mo_better_science()
If Postcount On Subject < 100 Then [Tired of BS] = "no" Else [Tired of BS] = "yes" End If
Call not_ugh()
If Postcount On Subject < 100 Then [Tired of BS] = "no" Else [Tired of BS] = "yes" End If
Call uhh_huh()
If Postcount On Subject < 100 Then [Tired of BS] = "no" Else [Tired of BS] = "yes" End If
Call various_dyno_proof()
If Postcount On Subject < 100 Then [Tired of BS] = "no" Else [Tired of BS] = "yes" End If
Call various_dyno_rebuttals()
If Postcount On Subject < 100 Then [Tired of BS] = "no" Else [Tired of BS] = "yes" End If
Call circular_logic()
If Postcount On Subject < 100 Then [Tired of BS] = "no" Else [Tired of BS] = "yes" End If
Call other_poster_is_a_poo_poo_head_and_fanboi()
If Postcount On Subject < 100 Then [Tired of BS] = "no" Else [Tired of BS] = "yes" End If
Loop
There - just run this little program to find out what happens.