Turbo V SC - ????
08-01-2007, 08:18 AM
#1
Cupcake Master
Thread Starter
Join Date: May 2006
Location: Craphole Florida
Posts: 236
Likes: 0
Received 0 Likes
on
0 Posts
Turbo V SC - ????
OK,
racking my brain here
i have read and reread alot of threads. I know the concept of how a turbo and a SC work, but my question is this:
If you are sitting at a dead stop and start to accelerate (MT) when do they actually kick in?
ive read about setting them for high rpm and low rpm, but if going with a MT how does that work? i've driven a turbo supra before, but it was an auto and really didnt pay attention to the turbo working.
what happens if you are driving and turbo is running, then you switch gears? you start a 6k rpm, then drop to 4k, does the turbo shut down, slow down???
i am a hands on type of guy, that actually has to fiddle with something to get a clearer understanding, but this wont happen on this occasion.
Disclaimer: i do not know if this is a repost, nor do i care
racking my brain here
i have read and reread alot of threads. I know the concept of how a turbo and a SC work, but my question is this:
If you are sitting at a dead stop and start to accelerate (MT) when do they actually kick in?
ive read about setting them for high rpm and low rpm, but if going with a MT how does that work? i've driven a turbo supra before, but it was an auto and really didnt pay attention to the turbo working.
what happens if you are driving and turbo is running, then you switch gears? you start a 6k rpm, then drop to 4k, does the turbo shut down, slow down???
i am a hands on type of guy, that actually has to fiddle with something to get a clearer understanding, but this wont happen on this occasion.
Disclaimer: i do not know if this is a repost, nor do i care
08-01-2007, 08:38 AM
#2
OK,
racking my brain here
i have read and reread alot of threads. I know the concept of how a turbo and a SC work, but my question is this:
If you are sitting at a dead stop and start to accelerate (MT) when do they actually kick in?
ive read about setting them for high rpm and low rpm, but if going with a MT how does that work? i've driven a turbo supra before, but it was an auto and really didnt pay attention to the turbo working.
what happens if you are driving and turbo is running, then you switch gears? you start a 6k rpm, then drop to 4k, does the turbo shut down, slow down???
i am a hands on type of guy, that actually has to fiddle with something to get a clearer understanding, but this wont happen on this occasion.
Disclaimer: i do not know if this is a repost, nor do i care
racking my brain here
i have read and reread alot of threads. I know the concept of how a turbo and a SC work, but my question is this:
If you are sitting at a dead stop and start to accelerate (MT) when do they actually kick in?
ive read about setting them for high rpm and low rpm, but if going with a MT how does that work? i've driven a turbo supra before, but it was an auto and really didnt pay attention to the turbo working.
what happens if you are driving and turbo is running, then you switch gears? you start a 6k rpm, then drop to 4k, does the turbo shut down, slow down???
i am a hands on type of guy, that actually has to fiddle with something to get a clearer understanding, but this wont happen on this occasion.
Disclaimer: i do not know if this is a repost, nor do i care
I believe it is said that a twin screw unit (properly sized) should produce FULL boost by no later than 1/3 of your RPM range ( if I am remembering this correctly). So in the 8 that would be ~3000rpm.
A turbo will hit full boost....well.....depends on how you size your turbo. You could spec out a turbo that would have full boost by 1000rpm if you wanted instant off idle response but it woudl probably fall short on the top end and not be able to deliver enough ar to maintain a positive manifold pressure.
When you shift to a higher gear your engine RPM's slow down so you volume of air comming out of your exhaust ports/manifold decreases and therefore so does the speed of the turbine on the turbo. If you are still flowing enough air to maintain full boost at the new RPM you...maintain.....full.....boost. If you don't flow enough, you end up with a lesser amount of positive manifold pressure until the turbo is able to spool back up.
You should read the books by Corkey Bell, Maximum Boost and Supercharged. Good reads for basic information that should give you a handle on this kind of stuff.
And also if you don't care if this is a repost you should realize there are plenty of people that won't care if you get an answer. There really is a TON of information on this site about this stuff along with the rest of the web that you have available to learn this stuff. If you don't care to learn it then go to a shop and pay your money - hope they don't lie to you - and be done with it.
08-01-2007, 08:47 AM
#3
Have you read this?
https://www.rx8club.com/series-i-major-horsepower-upgrades-93/power-adders-fi-dummies-turbo-supercharger-nitrous-122645/
If so, then step 2 would be to look at a compressor map of the turbo in question. The airflow amt of your engine and that map can help tell you when it boosts up. Theoretically, a SC kicks in right away. With a small turbo like the Greddy, it kicks in under 2000 RPM, which might as well be right away.
When you close throttle, the boost escapes via a blow off valve, or goes back and stalls the turbo. Either way, once you get back on the gas, the turbo starts spooling again. With a BOV there is not really any lag when shifting if you keep the RPM above the spool up threshold of the turbo.
https://www.rx8club.com/series-i-major-horsepower-upgrades-93/power-adders-fi-dummies-turbo-supercharger-nitrous-122645/
If so, then step 2 would be to look at a compressor map of the turbo in question. The airflow amt of your engine and that map can help tell you when it boosts up. Theoretically, a SC kicks in right away. With a small turbo like the Greddy, it kicks in under 2000 RPM, which might as well be right away.
When you close throttle, the boost escapes via a blow off valve, or goes back and stalls the turbo. Either way, once you get back on the gas, the turbo starts spooling again. With a BOV there is not really any lag when shifting if you keep the RPM above the spool up threshold of the turbo.
08-01-2007, 08:49 AM
#4
Cupcake Master
Thread Starter
Join Date: May 2006
Location: Craphole Florida
Posts: 236
Likes: 0
Received 0 Likes
on
0 Posts
Mac / Kane,
Thanks, you pretty much answered my question.
also, when i do ask questions, i usually read up before hand
and there is always someone who will post their information regardless of what i say, just the nature of man.
It is not that i dont care to learn it, but after everything i read i still just could not grasp those two questions i had.
also Kane, i did read that, great read that answered a couple other questions i had.
Thanks, you pretty much answered my question.
also, when i do ask questions, i usually read up before hand
and there is always someone who will post their information regardless of what i say, just the nature of man.
It is not that i dont care to learn it, but after everything i read i still just could not grasp those two questions i had.
also Kane, i did read that, great read that answered a couple other questions i had.
08-01-2007, 08:51 AM
#5
Basically, It all boils down to a SC being tied to engine rpm. Turbo is tied to the exhaust.
For the most part with a SC, when you shift, you get lower rpm, and as a result lower PSI till the revs increase. With a turbo, shifting generally wouldn't lower PSI.
BUT, it all depends.
If your turbo needs 6,000 rpm to spool up, then of course once you're lower then 6k, you're going to lack the desired pressure. But almost all turbos for the 8 will be hitting max psi in the 2500-4000 rpm range. So go WOT and you get peak boost and it stays there unless your rpms is lower than the minimum rpm needed.
With a SC, there are also exceptions. With the DNA supercharger, it's setup for peak power at peak rpm. So anytime you shift, you're going to drop 60+ hp. If your SC is setup for low end power, then shifting might not matter, since it maxes out down low.
For the most part with a SC, when you shift, you get lower rpm, and as a result lower PSI till the revs increase. With a turbo, shifting generally wouldn't lower PSI.
BUT, it all depends.
If your turbo needs 6,000 rpm to spool up, then of course once you're lower then 6k, you're going to lack the desired pressure. But almost all turbos for the 8 will be hitting max psi in the 2500-4000 rpm range. So go WOT and you get peak boost and it stays there unless your rpms is lower than the minimum rpm needed.
With a SC, there are also exceptions. With the DNA supercharger, it's setup for peak power at peak rpm. So anytime you shift, you're going to drop 60+ hp. If your SC is setup for low end power, then shifting might not matter, since it maxes out down low.
08-01-2007, 11:42 AM
#7
apostle you should meet up with brice and i am sure he would take you for a test ride.... his car is a lot of fun... jasons car is also bad ***... the range that the sc will provide the power over a turbo is in an area that you will never be racing in (2000-3000 rpm) and doyou really want more power when you are in the rpm range during daily driving
08-07-2007, 03:26 PM
#15
RotoRocks Powered
Originally Posted by 305WANKEL
I Wouldnt Recommend A Supercharger- The Pettit Unit Is A Joke( Dont Want To Offend Anyone ) But Rotaries Have Always Worked Good When Linked To Turbos And The "msp" Is No Exception-
08-07-2007, 03:45 PM
#16
Rotary 4 Life
iTrader: (1)
Join Date: Oct 2004
Location: Diamond Bar, California
Posts: 87
Likes: 0
Received 0 Likes
on
0 Posts
I read somewhere on the internet that our engines are major Dwell engines and that Turboing the car is somewhat pointless. Like our rotaries before that were Overlapping engines due to the position of the ports the Turbo was welcome with open arms. I have also heard this from a couple of D1 drivers too. They said that our Renesis would be good for N/A applications. I asked them if a supercharger would work. They said possibly, but wasnt too sure. Go figure right? I talk to the ones that drive turbo cars. Has anyone else heard this before?
08-07-2007, 05:05 PM
#17
RotoRocks Powered
I read somewhere on the internet that our engines are major Dwell engines and that Turboing the car is somewhat pointless. Like our rotaries before that were Overlapping engines due to the position of the ports the Turbo was welcome with open arms. I have also heard this from a couple of D1 drivers too. They said that our Renesis would be good for N/A applications. I asked them if a supercharger would work. They said possibly, but wasnt too sure. Go figure right? I talk to the ones that drive turbo cars. Has anyone else heard this before?
Seriously though, this is the first time I hear that.
but I tell ya what. If the experts say it can't be turboed, we must all listen to them. Right?
Last edited by rotorocks; 08-07-2007 at 05:07 PM.
08-07-2007, 05:10 PM
#18
^ Don't laugh, I heard about it too in this thread:
https://www.rx8club.com/showpost.php...8&postcount=16
Apparently turbos are just for show. I got mine for the Psssst sound.
https://www.rx8club.com/showpost.php...8&postcount=16
Apparently turbos are just for show. I got mine for the Psssst sound.
08-07-2007, 06:13 PM
#20
RotoRocks Powered
Thread
Thread Starter
Forum
Replies
Last Post
JimmyBlack
Series I Major Horsepower Upgrades
273
02-10-2020 10:23 PM
05rx8mazda
RX-8 Parts For Sale/Wanted
18
11-28-2015 09:42 AM