My ride in a Greddy turbo'd and Pettit Supercharged 8 (my visit to Pettit Racing)
04-24-2005, 05:35 PM
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Originally Posted by Icemastr
180 + 50% = 270. Not to mention the owner said he did a few modifications as well.
Boost at 3000RPM, even your peak boost target at 3000RPM is good for a turbocharger but it is not near peak torque right off of idle nor is it peak boost at 1500RPM. You are also forgetting a few things, peak boost does not mean peak torque, there is also a thing called boost response which is how fast your turbo spools when you are off the throttle and your already at the rpms your turbo would spool up then you step on the accelerator in addition you have throttle response which is how fast the charge pipes and intercooler fill up to volume before your intake becomes pressurized and you start putting the power to the ground. These are all areas where the supercharger has a big advantage, its not just the powerband below 3000RPMs. Your going to tell me about turbo sizing and how flat the torque curve is? I have 8 turbos sitting in my garage right now as well as several intercoolers and various other parts. I slap turbos on cars just for the heck of it like my 89 dodge caravan. I co-drive and help with an SM2 car that has the best power delivery of any turbocharged rotary I have ever seen in all my years because of its ECU tuning and proper setup. It does things people think no one could do on the stock turbos and goes against the accepeted with many of the modifications it has.
Pettit will come out with good stuff. The original posters comment about the supercharger kit being priced similarily to the Greddy kit certainly makes things interesting. For comparison an 8 psi 1.2L Whipple supercharger kit makes 215rwhp on a 1.8L miata motor. I find it hard to believe that a larger supercharger on an engine that makes 80 more whp stock barely makes the same HP at the same boost level. There is no reason I can see except possibly the ECU that a supercharger making over 250rwhp isnt feasible. I am not bashing the greddy kit as I am very impressed with what it does for the price, my opinion is for people considering forced induction is to listen to people with all different types of products and talk to people with experience on various setups and try and drive a car with one of these setups before making your decision.
Boost at 3000RPM, even your peak boost target at 3000RPM is good for a turbocharger but it is not near peak torque right off of idle nor is it peak boost at 1500RPM. You are also forgetting a few things, peak boost does not mean peak torque, there is also a thing called boost response which is how fast your turbo spools when you are off the throttle and your already at the rpms your turbo would spool up then you step on the accelerator in addition you have throttle response which is how fast the charge pipes and intercooler fill up to volume before your intake becomes pressurized and you start putting the power to the ground. These are all areas where the supercharger has a big advantage, its not just the powerband below 3000RPMs. Your going to tell me about turbo sizing and how flat the torque curve is? I have 8 turbos sitting in my garage right now as well as several intercoolers and various other parts. I slap turbos on cars just for the heck of it like my 89 dodge caravan. I co-drive and help with an SM2 car that has the best power delivery of any turbocharged rotary I have ever seen in all my years because of its ECU tuning and proper setup. It does things people think no one could do on the stock turbos and goes against the accepeted with many of the modifications it has.
Pettit will come out with good stuff. The original posters comment about the supercharger kit being priced similarily to the Greddy kit certainly makes things interesting. For comparison an 8 psi 1.2L Whipple supercharger kit makes 215rwhp on a 1.8L miata motor. I find it hard to believe that a larger supercharger on an engine that makes 80 more whp stock barely makes the same HP at the same boost level. There is no reason I can see except possibly the ECU that a supercharger making over 250rwhp isnt feasible. I am not bashing the greddy kit as I am very impressed with what it does for the price, my opinion is for people considering forced induction is to listen to people with all different types of products and talk to people with experience on various setups and try and drive a car with one of these setups before making your decision.
For a car that revs to 9000, 2500-3000 RPM is pretty much right off idle, and time to boost is literally instantaneous given the fact that the kit is running 6-7 psi max. It's not like we have to go off vacuum & push 19 psi through the kit & wait. Literally I step on the gas & I get full boost.
You are saying that there must be more hp to be gained because a smaller unit that you had on you Miata was making similar hp, so a bigger unit, running on a engine that puts out more hp. making the same boost should be able to make more power, maybe it is the ECU. Could very well be right, but I'm just going off what Pettit is claiming on their website & what they said in the test article. They claim 50 hp. They are saying it, not us. Hopefully, later on they might be able to revise the ECU & deliver more hp from the unit.
I am really happy that there are more choices coming out for this car. I would really like to see some really good stuff for our car, and hopefully we can supoort a strong aftermarket.
04-25-2005, 08:06 PM
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I spoke with Candy from Pettit racing today. Their reason for stating the reliability of a turbo will be less then that of a supercharger is because of the added heat in the engine bay.
04-25-2005, 08:30 PM
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Originally Posted by guitarjunkie28
in anyne's defense, all the motors i've taken apart have looked pretty hammered on the side seals and bearings. i don't think it's from the turbo or any other mods, although they may accelerate wear.
what i'm starting to do is recommend changine the side seals to all my customers when i port/rebuild. it's an extra ~$200, but well worth it in the long run.
what i'm starting to do is recommend changine the side seals to all my customers when i port/rebuild. it's an extra ~$200, but well worth it in the long run.
what kinda seals do you recomend to change to?
hmm this sounds firmiliar...have i asked you this before in anouther thread? lol if so sorry for the ? again..but i forgot where i asked it last:p
04-26-2005, 12:56 AM
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Hey All-
I'm back home from Florida, and caught up with the comments to my orig post.
I will try and get another ride in the Turbo'd RX8 - maybe this weekend if I can get a hold of Phil- while the Pettit ride is fresh in my mind. I'll also ask him to really show me what it can do off the line.
Also an far as price, Pettit commented "around $3500" (I thought that's what the greddy MSPR was) I'm so used to not quoting prices from being on AVSforum- (they are pretty strict) I just should have mentioned that up front.
I'm back home from Florida, and caught up with the comments to my orig post.
I will try and get another ride in the Turbo'd RX8 - maybe this weekend if I can get a hold of Phil- while the Pettit ride is fresh in my mind. I'll also ask him to really show me what it can do off the line.
Also an far as price, Pettit commented "around $3500" (I thought that's what the greddy MSPR was) I'm so used to not quoting prices from being on AVSforum- (they are pretty strict) I just should have mentioned that up front.
04-26-2005, 01:26 AM
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emailists;
I am glad you enjoyed your trip to South Florida and Pettit racing they are a class act! I had some work done there. We also have a company called Jap Trix Inc. they are rotary specialist. They took me for a ride in there RX8 with a Greddy turbo and it was fast! Just the sound of the bov made me feel good! Check out there web site.
You need quicktime to play the vids!
http://www.japtrix.com/index.html
I am glad you enjoyed your trip to South Florida and Pettit racing they are a class act! I had some work done there. We also have a company called Jap Trix Inc. they are rotary specialist. They took me for a ride in there RX8 with a Greddy turbo and it was fast! Just the sound of the bov made me feel good! Check out there web site.
You need quicktime to play the vids!
http://www.japtrix.com/index.html
04-26-2005, 01:38 AM
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Originally Posted by emailists
Also an far as price, Pettit commented "around $3500" (I thought that's what the greddy MSPR was)
04-26-2005, 06:55 AM
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Originally Posted by emailists
.......whose innovative design had one set of blades traveling twice as fast as the set it interleaves with..................
Can you shed a little light on how this is accomplished?
And, contrary to other opinions - great write up on your impressions of both cars.
04-26-2005, 10:44 AM
#36
RX8 and a Truk....
Originally Posted by Moostafa29
Never said it was GReddy.
04-26-2005, 02:22 PM
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Originally Posted by Icemastr
All you have to do is give one vane a different gear set than the other to make it turn faster or slower.
If the vanes spun separately and without overlap, there would be no boost..........
04-26-2005, 02:31 PM
#38
RX8 and a Truk....
Originally Posted by tpryor
I get the logic of gearing one side different than the other, but if they INTERLEAVE (as most supercharger vanes do) the question becomes how is it PHYSICALLY possible to do it? Since the vanes overlap, how can it be possible for one to turn faster than the other?
If the vanes spun separately and without overlap, there would be no boost..........
If the vanes spun separately and without overlap, there would be no boost..........
Maybe have them different size? Think of gears in a wristwatch or other clock. A small, fast-spinning gear turns a larger, slower gear.
Maybe?
04-27-2005, 12:23 AM
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I just remembered another detail... Pettit said they felt the Greddy kit (or some part thereof) hung so low it could get wet from a puddle and be damaged. Any thoughts on this?
I won't be able to get another ride in that turbo this weekend. The NY Home theater and Hi fi show is in town, and I have to feed my other (original) obsession, audio and video. I'll try next weekend. (i'll be too busy listening to $40K MBL egg shaped speakers and wondering why I didn't pick a proffession I could make some real money in)
IZoom PM'd me asking if I knew about release dates (they didn't tell me any) and if it were an air to air intercooler. I'm not sure since I didn't see it- but it did mount in the front bumper.
Also they didn't mention a low and high boost model. They did mention that the boost really trailed off at top RPM by design. The more I think about the Pettit ride, it really seems like it was mostly down low off the line and not too much in 4th and above. This is of course without the intercooler and without their final fuel management, so that could improve somewhat.
I won't be able to get another ride in that turbo this weekend. The NY Home theater and Hi fi show is in town, and I have to feed my other (original) obsession, audio and video. I'll try next weekend. (i'll be too busy listening to $40K MBL egg shaped speakers and wondering why I didn't pick a proffession I could make some real money in)
IZoom PM'd me asking if I knew about release dates (they didn't tell me any) and if it were an air to air intercooler. I'm not sure since I didn't see it- but it did mount in the front bumper.
Also they didn't mention a low and high boost model. They did mention that the boost really trailed off at top RPM by design. The more I think about the Pettit ride, it really seems like it was mostly down low off the line and not too much in 4th and above. This is of course without the intercooler and without their final fuel management, so that could improve somewhat.
Last edited by emailists; 04-27-2005 at 12:25 AM.
04-27-2005, 12:26 PM
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The question is was there a big box somewhere in the intake path that housed an air-to-water box. The front intercooler can be either air-to-air or water-to-air.
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04-27-2005, 03:45 PM
#42
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Originally Posted by emailists
I just remembered another detail... Pettit said they felt the Greddy kit (or some part thereof) hung so low it could get wet from a puddle and be damaged. Any thoughts on this?
04-27-2005, 07:52 PM
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The only questions I have are 1. What is PTP doing to get so much HP out of the Renesis when Greddy is running the same PSI but getting ~60hp less. Are they running a much more aggressive A/F? 2. How much will a 60% increase in power levels reduce the lifespan of the engine?
04-27-2005, 08:35 PM
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Originally Posted by rkostolni
The only questions I have are 1. What is PTP doing to get so much HP out of the Renesis when Greddy is running the same PSI but getting ~60hp less. Are they running a much more aggressive A/F? 2. How much will a 60% increase in power levels reduce the lifespan of the engine?
Nobody knows that yet, as nobody has put that kind've mileage on these engines. Unless PTP, Pettit or RB might want to chime in.
04-27-2005, 10:54 PM
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Boost is not boost. A larger turbo can flow air more efficiently so it creates less heat therefore more air flow with the same level of pressure will create more HP.
04-28-2005, 09:44 AM
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Pressure is pressure in the intake manifold. I haven't heard of any accuracy problems due to sensor mounting however there can be accuracy problems with the type of gauge used. I no longer use autometer, at least not the cheap ones because my autometer boost gauge was off 0-2 psi all the time compared to the sensor readings on my ECU. 2 psi can be a pretty big difference between just right and too much boost. In addition yes RotaryGod, I am quite sure the Greddy turbo kit is not as exposed as the Porsche 911 turbochargers as well as many other turbo systems stock and aftermarket. Plus isnt there a shield underneath the engine anyways that blocks debris?
04-29-2005, 12:01 PM
#49
Thanks for the nice write up. It is good to see some others validating to a certain extent my original choices in the Autorotor, albeit mine is a larger unit AFAIK.
The screws (not vanes) in the autorotor don't have a 2:1 ratio. It is more like a 7:5 or 6:4 or something. The male and female rotors have a different number or lobes.
Cheers,
Hymee.
The screws (not vanes) in the autorotor don't have a 2:1 ratio. It is more like a 7:5 or 6:4 or something. The male and female rotors have a different number or lobes.
Cheers,
Hymee.
05-01-2005, 01:12 AM
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I would love some more info regarding these two kits. If anyone has any other experiences, please share them!!!!!
Does Pettit's supercharger make the the typical S/C whistle? I think I heard somewhere that it is very quiet. I hope not, I love the high pitched squeel!!!
Does Pettit's supercharger make the the typical S/C whistle? I think I heard somewhere that it is very quiet. I hope not, I love the high pitched squeel!!!