Safe Boost on Stock 13B?
02-06-12, 03:17 PM
#1
Safe Boost on Stock 13B?
I was interested in learning about what boost levels can a stock S4 13B TII handle safely. This question is assuming that everything is properly tuned and there are not fuel restrictions and such. I would just like to know what the stock internals in this engine can handle safely. Also assuming the engine the engine has a stock port job as well. I assume this question has been answered before, but I would just like a straight answer just to be sure. Thanks
02-10-12, 04:16 PM
#2
always something to fix
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I would say 14 or 15 psi, depending on your set up.
You don't find very many stock fds now days, even something like aftermarket IC effects your psi somewhat
You don't find very many stock fds now days, even something like aftermarket IC effects your psi somewhat
02-10-12, 06:29 PM
#3
^That is a very misleading and general statement. Different turbo's at the same psi will flow very different amounts of air.
The big questions are what turbo? What injectors? and what intercooler? 'Safe' really depends on the individual setup. With bigger injectors, turbo, fuel pump, intercooler, ecu, excellent tune, etc, the block itself can usually handle about 350hp.
The big questions are what turbo? What injectors? and what intercooler? 'Safe' really depends on the individual setup. With bigger injectors, turbo, fuel pump, intercooler, ecu, excellent tune, etc, the block itself can usually handle about 350hp.
02-10-12, 08:05 PM
#5
^That is a very misleading and general statement. Different turbo's at the same psi will flow very different amounts of air.
The big questions are what turbo? What injectors? and what intercooler? 'Safe' really depends on the individual setup. With bigger injectors, turbo, fuel pump, intercooler, ecu, excellent tune, etc, the block itself can usually handle about 350hp.
The big questions are what turbo? What injectors? and what intercooler? 'Safe' really depends on the individual setup. With bigger injectors, turbo, fuel pump, intercooler, ecu, excellent tune, etc, the block itself can usually handle about 350hp.
Last edited by Silver Comet; 02-10-12 at 08:07 PM.
02-10-12, 09:26 PM
#6
hukd in fonikz
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10psi is a good safety number.
On a bone stock engine it's really going to boil down to the condition of the car. Moreover the fuel system. If you have a weak fuel pump, bad fuel filter, or a gummed up injector it will lean out long before 10psi.
My personal opinion is that you need a good wideband setup before you start tweaking the boost. It will allow you to monitor the AFR as you increase boost to make sure your not going overboard. Again, personal opinion is the Innovate LC1 system. I'v run several of them and love em for the price. I'm also kinda partial to the TurboXS manual boost controllers. They have made a good combo for me several times.
On a bone stock engine it's really going to boil down to the condition of the car. Moreover the fuel system. If you have a weak fuel pump, bad fuel filter, or a gummed up injector it will lean out long before 10psi.
My personal opinion is that you need a good wideband setup before you start tweaking the boost. It will allow you to monitor the AFR as you increase boost to make sure your not going overboard. Again, personal opinion is the Innovate LC1 system. I'v run several of them and love em for the price. I'm also kinda partial to the TurboXS manual boost controllers. They have made a good combo for me several times.
02-10-12, 09:56 PM
#7
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^That is a very misleading and general statement. Different turbo's at the same psi will flow very different amounts of air.
The big questions are what turbo? What injectors? and what intercooler? 'Safe' really depends on the individual setup. With bigger injectors, turbo, fuel pump, intercooler, ecu, excellent tune, etc, the block itself can usually handle about 350hp.
The big questions are what turbo? What injectors? and what intercooler? 'Safe' really depends on the individual setup. With bigger injectors, turbo, fuel pump, intercooler, ecu, excellent tune, etc, the block itself can usually handle about 350hp.
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02-10-12, 10:54 PM
#8
The stock turbo is well outside its efficiency range by about 12 psi. Pushing it further is pointless, and will lead to higher IATs and risk of detonation.
If you're talking about what the engine itself can take, there are few modifications made to the actual block on high-HP builds. IIRC, an S4 rear iron can be broken around the 450-500 whp range. Certain S5 rear irons have reinforced castings, and can handle more. Engines can also be strengthened with additional dowels.
If you're talking about what the engine itself can take, there are few modifications made to the actual block on high-HP builds. IIRC, an S4 rear iron can be broken around the 450-500 whp range. Certain S5 rear irons have reinforced castings, and can handle more. Engines can also be strengthened with additional dowels.
02-12-12, 02:36 AM
#11
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- Fuel octane rating
- Intercooler efficiency
- Compressor efficiency
- Air pressure (yes, altitude affects this)
- Air temperature
- Air humidity
- Engine temperature (affected by radiator, oil cooler, thermostat, etc.)
- Engine load (driving up a hill, rapid acceleration, pulling a lot of weight, etc.)
- Compression ratio of the rotors
- Fuel/Air ratio
- Ignition timing
For example, if your engine has 9.7:1 rotors, no intercooler, and a crummy Mexican Ebay turbocharger, and you live in Death Valley, use 87 octane fuel, and attempted to tune the engine yourself, then the engine will detonate at a low boost level. However, if your engine has 8.5:1 rotors, an efficient front-mounted Spearco intercooler, an efficient Garrett GTR turbo, you live in Aspen Colorado, use 115 octane race fuel, and paid for professional tuning, then the engine will be able to run much more boost before it detonates. This is why you need to take it with a grain of salt when forum members chime in about how "My engine runs ten million psi boost with no problem".
Given that, see this below website for some good general guidance. It is a bit out of date, so check with this forum before you buy anything that may have been superseded by a better product. For example, the FCD has been made obsolete by the Rtek ECU upgrade.
http://fc3spro.com/TECH/FM2W/power.htm
02-12-12, 02:58 AM
#12
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If you're looking for a good example, my motor's on 70,000KM's and still has 95psi on all faces, and it's been run with 10psi of boost on stock turbo since birth. I just keep my fuel filter fresh, and have an upgraded fuel pump (Walbro 255). I run 94 octane for peace of mind as well.
02-14-12, 03:53 AM
#13
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If you're looking for a good example, my motor's on 70,000KM's and still has 95psi on all faces, and it's been run with 10psi of boost on stock turbo since birth. I just keep my fuel filter fresh, and have an upgraded fuel pump (Walbro 255). I run 94 octane for peace of mind as well.
02-14-12, 10:13 AM
#14
bcrotary.
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My setup is:
- S4 13B
- S5 Turbo
- S6 Rotors
- FCD
- Blitz Boost Controller @ 10psi
- Walbro 255 Fuel Pump
- Stock Injectors
It's a very basic setup, but it's holding up fine. As for compression, I've had the car 5 months and only checked it last month. I'll probably check it every 6 months.
- S4 13B
- S5 Turbo
- S6 Rotors
- FCD
- Blitz Boost Controller @ 10psi
- Walbro 255 Fuel Pump
- Stock Injectors
It's a very basic setup, but it's holding up fine. As for compression, I've had the car 5 months and only checked it last month. I'll probably check it every 6 months.
02-14-12, 10:28 AM
#15
My setup is:
- S4 13B
- S5 Turbo
- S6 Rotors
- FCD
- Blitz Boost Controller @ 10psi
- Walbro 255 Fuel Pump
- Stock Injectors
It's a very basic setup, but it's holding up fine. As for compression, I've had the car 5 months and only checked it last month. I'll probably check it every 6 months.
- S4 13B
- S5 Turbo
- S6 Rotors
- FCD
- Blitz Boost Controller @ 10psi
- Walbro 255 Fuel Pump
- Stock Injectors
It's a very basic setup, but it's holding up fine. As for compression, I've had the car 5 months and only checked it last month. I'll probably check it every 6 months.
^ Props for the proper use of an FCD!
02-14-12, 12:59 PM
#16
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My setup is:
- S4 13B
- S5 Turbo
- S6 Rotors
- FCD
- Blitz Boost Controller @ 10psi
- Walbro 255 Fuel Pump
- Stock Injectors
It's a very basic setup, but it's holding up fine. As for compression, I've had the car 5 months and only checked it last month. I'll probably check it every 6 months.
- S4 13B
- S5 Turbo
- S6 Rotors
- FCD
- Blitz Boost Controller @ 10psi
- Walbro 255 Fuel Pump
- Stock Injectors
It's a very basic setup, but it's holding up fine. As for compression, I've had the car 5 months and only checked it last month. I'll probably check it every 6 months.
02-14-12, 01:39 PM
#17
lambof.god, your setup really is the bare minimum to safely run that boost level on the stock turbo. The walbro fuel pump drives up fuel pressure by overwhelming the stock FPR, which is keeping you from detonating in the mid-range. With a stock fuel pump and injectors, there is a lean spot just before the 3800 RPM secondary transition when they hit max D/C under higher boost.
The same setup with a stock fuel pump or even an FD pump would be a recipe for disaster due to lack of fuel and the negative effects FCDs have on fuel and timing calculations.
The same setup with a stock fuel pump or even an FD pump would be a recipe for disaster due to lack of fuel and the negative effects FCDs have on fuel and timing calculations.
02-14-12, 09:51 PM
#18
bcrotary.
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whats your estimated hp?
The same setup with a stock fuel pump or even an FD pump would be a recipe for disaster due to lack of fuel and the negative effects FCDs have on fuel and timing calculations.
To validate my statement about the PO; I recently found out that the fuel filter hadn't been changed for 4 years.. Shocking.
02-15-12, 10:59 AM
#19
lambof.god, your setup really is the bare minimum to safely run that boost level on the stock turbo. The walbro fuel pump drives up fuel pressure by overwhelming the stock FPR, which is keeping you from detonating in the mid-range. With a stock fuel pump and injectors, there is a lean spot just before the 3800 RPM secondary transition when they hit max D/C under higher boost.
The same setup with a stock fuel pump or even an FD pump would be a recipe for disaster due to lack of fuel and the negative effects FCDs have on fuel and timing calculations.
The same setup with a stock fuel pump or even an FD pump would be a recipe for disaster due to lack of fuel and the negative effects FCDs have on fuel and timing calculations.
02-15-12, 03:07 PM
#20
S4 Love
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lambof.god, your setup really is the bare minimum to safely run that boost level on the stock turbo. The walbro fuel pump drives up fuel pressure by overwhelming the stock FPR, which is keeping you from detonating in the mid-range. With a stock fuel pump and injectors, there is a lean spot just before the 3800 RPM secondary transition when they hit max D/C under higher boost.
The same setup with a stock fuel pump or even an FD pump would be a recipe for disaster due to lack of fuel and the negative effects FCDs have on fuel and timing calculations.
The same setup with a stock fuel pump or even an FD pump would be a recipe for disaster due to lack of fuel and the negative effects FCDs have on fuel and timing calculations.
02-15-12, 11:57 PM
#21
I've been wanting to swap out my walbro for an FD pump because it was overpowering my stock FPR and running rich on an Rtek 1.7. I know the switchover is lowered to 3500rpm, but has it been verified that the 10psi of boost at stock fuel pressure doesn't have the lean spot?
Here's the thread discussing it: https://www.rx7club.com/rtek-forum-168/secondary-staging-issue-844350/
Higher fuel pressure due to FPR overrun means a richer mixture across the board. It's a crude way to compensate. The worst of it is under vacuum, where I measured fuel pressure as much as 10 psi higher than stock.
When I measured fuel pressure with my FD pump, it ended up being almost exactly the same as the FSM specs for the TII pump.
03-13-12, 01:55 PM
#22
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Reviving this to ask a question after doing all my research and searching. What EXACTLY is considered safe on a stock turbo with a high milage engine? Lets say the 160k mi mark. The main thing at this point would be to keep it running as sound as possible. Lets take into this consideration:
-rebuilt hitachi using a 360 thrust bearing and ported wastegate
-stock fuel injectors
-stock ecu
-stock fuel pump
-stock everything for the most part
-rebuilt hitachi using a 360 thrust bearing and ported wastegate
-stock fuel injectors
-stock ecu
-stock fuel pump
-stock everything for the most part
03-13-12, 04:42 PM
#23
Thanks for the info RR88! Good stuff!
@ 160k, I'd consider a turbo engine to be on borrowed time. The safest way to run it is how it was designed. With all stock parts, running at stock boost using the wastegate spring.
Reviving this to ask a question after doing all my research and searching. What EXACTLY is considered safe on a stock turbo with a high milage engine? Lets say the 160k mi mark. The main thing at this point would be to keep it running as sound as possible. Lets take into this consideration:
-rebuilt hitachi using a 360 thrust bearing and ported wastegate
-stock fuel injectors
-stock ecu
-stock fuel pump
-stock everything for the most part
-rebuilt hitachi using a 360 thrust bearing and ported wastegate
-stock fuel injectors
-stock ecu
-stock fuel pump
-stock everything for the most part
03-13-12, 05:45 PM
#24
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The OP specified "stock internals", which means stock rotors, eccentric shaft, and associated gears, seals, etc., inside the engine. The turbo, injectors, and intercooler are external.
Excellent question. No, 12 psi is not a solid number. See below for more...
A boost gauge is not a very good limit indicator. There are two main factors that limit the amount of boost pressure: 1) The point at which the engine fails mechanically, and 2) The point at which the engine detonates. Since the engine will most likely detonate before it bursts from pressure or strain, let's look at some of the factors that affect the detonation threshold:
- Fuel octane rating
- Intercooler efficiency
- Compressor efficiency
- Air pressure (yes, altitude affects this)
- Air temperature
- Air humidity
- Engine temperature (affected by radiator, oil cooler, thermostat, etc.)
- Engine load (driving up a hill, rapid acceleration, pulling a lot of weight, etc.)
- Compression ratio of the rotors
- Fuel/Air ratio
- Ignition timing
For example, if your engine has 9.7:1 rotors, no intercooler, and a crummy Mexican Ebay turbocharger, and you live in Death Valley, use 87 octane fuel, and attempted to tune the engine yourself, then the engine will detonate at a low boost level. However, if your engine has 8.5:1 rotors, an efficient front-mounted Spearco intercooler, an efficient Garrett GTR turbo, you live in Aspen Colorado, use 115 octane race fuel, and paid for professional tuning, then the engine will be able to run much more boost before it detonates. This is why you need to take it with a grain of salt when forum members chime in about how "My engine runs ten million psi boost with no problem".
Given that, see this below website for some good general guidance. It is a bit out of date, so check with this forum before you buy anything that may have been superseded by a better product. For example, the FCD has been made obsolete by the Rtek ECU upgrade.
http://fc3spro.com/TECH/FM2W/power.htm
Excellent question. No, 12 psi is not a solid number. See below for more...
A boost gauge is not a very good limit indicator. There are two main factors that limit the amount of boost pressure: 1) The point at which the engine fails mechanically, and 2) The point at which the engine detonates. Since the engine will most likely detonate before it bursts from pressure or strain, let's look at some of the factors that affect the detonation threshold:
- Fuel octane rating
- Intercooler efficiency
- Compressor efficiency
- Air pressure (yes, altitude affects this)
- Air temperature
- Air humidity
- Engine temperature (affected by radiator, oil cooler, thermostat, etc.)
- Engine load (driving up a hill, rapid acceleration, pulling a lot of weight, etc.)
- Compression ratio of the rotors
- Fuel/Air ratio
- Ignition timing
For example, if your engine has 9.7:1 rotors, no intercooler, and a crummy Mexican Ebay turbocharger, and you live in Death Valley, use 87 octane fuel, and attempted to tune the engine yourself, then the engine will detonate at a low boost level. However, if your engine has 8.5:1 rotors, an efficient front-mounted Spearco intercooler, an efficient Garrett GTR turbo, you live in Aspen Colorado, use 115 octane race fuel, and paid for professional tuning, then the engine will be able to run much more boost before it detonates. This is why you need to take it with a grain of salt when forum members chime in about how "My engine runs ten million psi boost with no problem".
Given that, see this below website for some good general guidance. It is a bit out of date, so check with this forum before you buy anything that may have been superseded by a better product. For example, the FCD has been made obsolete by the Rtek ECU upgrade.
http://fc3spro.com/TECH/FM2W/power.htm
Best short answer I've seen for such a complicated question as the OP had in a long time. The learning curve for engine management and function is super steep to a point and then it plateaus and you realize you only need to ask yourself these two basic questions.
