Rear Mount Turbo?
Rear Mount Turbo?
01-08-2013, 05:40 PM
#4
2009 RX-8 Touring
Rear-mount turbos are awful, especially on small-displacement cars. The lag is mind-boggling, because it takes so long for the turbo to pressurize the super-long intake runner. It's seriously pointless unless you're drag-racing and you have the opportunity to pre-rev the engine every time you pull away from a stop.
01-08-2013, 05:47 PM
#6
SARX Legend
iTrader: (46)
Rear-mount turbos are awful, especially on small-displacement cars. The lag is mind-boggling, because it takes so long for the turbo to pressurize the super-long intake runner. It's seriously pointless unless you're drag-racing and you have the opportunity to pre-rev the engine every time you pull away from a stop.
01-09-2013, 11:31 AM
#7
2009 RX-8 Touring
Blow me, 9k. The same turbocharger, powered by the same exhaust stream, will take a longer time to pressurize a larger intake runner than a smaller intake runner. Physics always wins.
01-09-2013, 11:58 AM
#8
SARX Legend
iTrader: (46)
Yeah, talk when you actually have some personal experience on the subject. Until then, you are just talking out of your *** and stating your own uneducated opinion on the subject. Bumblebeerx8's rear mount Turbo RX-8 pulls like a freight train and is one of the best turbo RX-8 builds to date.
01-09-2013, 12:08 PM
#9
Yeah, talk when you actually have some personal experience on the subject. Until then, you are just talking out of your *** and stating your own uneducated opinion on the subject. Bumblebeerx8's rear mount Turbo RX-8 pulls like a freight train and is one of the best turbo RX-8 builds to date.
STS was looking to build a kit for the RX8, back about 2005. The project was stillborn due to the lack of options for engine management at the time.
01-09-2013, 01:01 PM
#10
Might be useful for some to check out the FAQ's etc from the STS Turbo website: STS Turbo, Inc. - Benefits of STS Systems
Short version: The turbo chosen will be different that that for a front-mount. For modest boost levels, an intercooler isn't needed, saving not only that volume, but greatly reducing the flow resistance. Extra oil cooling for the extra hp is often not needed due to the cooling in the long oil lines between engine and turbo. The time to pressure charge the intake tube is given as 0.05 seconds. Eliminating or downsizing the muffler can bring the added weight close to zero. The reduced temperatures increase turbo life and eliminate the need for high temp exhaust materials and shielding or heat-proofing underhood components. The lower temps also eliminate the need for a turbo timer.
YMMV
Short version: The turbo chosen will be different that that for a front-mount. For modest boost levels, an intercooler isn't needed, saving not only that volume, but greatly reducing the flow resistance. Extra oil cooling for the extra hp is often not needed due to the cooling in the long oil lines between engine and turbo. The time to pressure charge the intake tube is given as 0.05 seconds. Eliminating or downsizing the muffler can bring the added weight close to zero. The reduced temperatures increase turbo life and eliminate the need for high temp exhaust materials and shielding or heat-proofing underhood components. The lower temps also eliminate the need for a turbo timer.
YMMV
01-09-2013, 01:34 PM
#11
SARX Legend
iTrader: (46)
I saw this car, this past summer, at a car show. It was the main reason I went. I've followed his build since day one. It looks nice. I didn't get a chance to see it perform, but I'm sure it's top notch.
STS was looking to build a kit for the RX8, back about 2005. The project was stillborn due to the lack of options for engine management at the time.
STS was looking to build a kit for the RX8, back about 2005. The project was stillborn due to the lack of options for engine management at the time.
He is an excellent fabricator (professional by trade) and doesn't cut any corners. When my car goes under the knife on the next build he will certainly have a hand in it. It's just too bad he lives so far from me.
Last edited by 9krpmrx8; 01-09-2013 at 01:37 PM.
01-09-2013, 01:43 PM
#12
SARX Legend
iTrader: (46)
Might be useful for some to check out the FAQ's etc from the STS Turbo website: STS Turbo, Inc. - Benefits of STS Systems
Short version: The turbo chosen will be different that that for a front-mount. For modest boost levels, an intercooler isn't needed, saving not only that volume, but greatly reducing the flow resistance. Extra oil cooling for the extra hp is often not needed due to the cooling in the long oil lines between engine and turbo. The time to pressure charge the intake tube is given as 0.05 seconds. Eliminating or downsizing the muffler can bring the added weight close to zero. The reduced temperatures increase turbo life and eliminate the need for high temp exhaust materials and shielding or heat-proofing underhood components. The lower temps also eliminate the need for a turbo timer.
YMMV
Short version: The turbo chosen will be different that that for a front-mount. For modest boost levels, an intercooler isn't needed, saving not only that volume, but greatly reducing the flow resistance. Extra oil cooling for the extra hp is often not needed due to the cooling in the long oil lines between engine and turbo. The time to pressure charge the intake tube is given as 0.05 seconds. Eliminating or downsizing the muffler can bring the added weight close to zero. The reduced temperatures increase turbo life and eliminate the need for high temp exhaust materials and shielding or heat-proofing underhood components. The lower temps also eliminate the need for a turbo timer.
YMMV
He doesn't have a clue and it's obvious he knows nothing about rear mounts or modern turbos. I know a guy I used to drag race with that has an 80's model Chevy pick-up with a home made rear mount kit and it is the ultimate sleeper and runs 12's in the 1/4 mile. It is 90% bone stock in appearance. I can only imagine what it would do with a proper modern turbo and supporting hardware but he just did it for the fun of it. I have also seen numerous rear mount Vettes at the track over the years. Most who speak of turbo lag have never turbocharged anything (or at least not in the past 10 years).
01-09-2013, 01:43 PM
#13
I have had a 3rd gear drag race from a roll . My side mount setup vs a mid mount setup (turbo sitting where cat was) . Both cars fully tuned and running well with almost identical sized turbos running same boost .
Difference at spool up was ............................HUGE !!!!!
Difference at spool up was ............................HUGE !!!!!
01-09-2013, 02:13 PM
#14
SARX Legend
iTrader: (46)
I have had a 3rd gear drag race from a roll . My side mount setup vs a mid mount setup (turbo sitting where cat was) . Both cars fully tuned and running well with almost identical sized turbos running same boost .
Difference at spool up was ............................HUGE !!!!!
Difference at spool up was ............................HUGE !!!!!
Yeah man but there are so many variables that could have contributed to that outcome. Picking a properly sized turbo is so important (I wish I had done more homework when picking mine). I'm not familiar with the mid mount setup you are referring too and it's configuration. But the idea that a rear mount system in general is inferior to other setups is just silly.
01-09-2013, 02:23 PM
#16
Yeah man but there are so many variables that could have contributed to that outcome. Picking a properly sized turbo is so important (I wish I had done more homework when picking mine). I'm not familiar with the mid mount setup you are referring too and it's configuration. But the idea that a rear mount system in general is inferior to other setups is just silly.
He was also talking about upgrading it to a GTX too.
01-15-2013, 01:15 PM
#19
Just found this, you guys crack me up. I will say there are quite a few changes since my original build. It is very possible and is quite hard because of the lack of info or *** hats that jump to the first conclusion that the lag is horrible. As for the GTX/HTA upgrade I still have not decided its worth the extra for who knows what real gain. Really need to fully tune what I have and quit changing things first
01-15-2013, 07:22 PM
#21
Oh no did not quit. After I spoke with you I did the fuel stuff and changed a few other things I had talks with you and others about. Every thing on the turbo end is great and was moving forward good with Brettus. I ran into a burnt up alternator and then winter so I kinda threw it on the back burner. I have a used OEM alternator on the way and have thought about a High Output one.
01-18-2013, 02:50 AM
#23
Oh no did not quit. After I spoke with you I did the fuel stuff and changed a few other things I had talks with you and others about. Every thing on the turbo end is great and was moving forward good with Brettus. I ran into a burnt up alternator and then winter so I kinda threw it on the back burner. I have a used OEM alternator on the way and have thought about a High Output one.
