Will an exhaust system blow up my old engine?
12-28-04, 10:15 PM
#1
I'd hit it.
Thread Starter
Join Date: Feb 2004
Location: Texas
Posts: 833
Likes: 0
Received 0 Likes
on
0 Posts
Will an exhaust system blow up my old engine?
I have a 1988 turbo II, all stock except for a K&N intake. It has 108k miles on it but it still runs great, it doesn't smoke, there are no issues with it at all. I want to put a big ole exhaust system on it because i hear it makes a big difference on turbo cars. My question is would this be safe to do, or will it blow up my 108k mile engine under the added poost pressure? I take really good care of the car and I rarely drive it hard, let it cool off before shutting it down, etc so its not like I will run the **** out of it all the time. I have planned on doing this for a while now, so I already have the fuel cut switch and a new boost gauge installed. I have always heard that any added boost pressure is bad for and engine, so I am concerned. Also, is there anything I can do to protect the engine from damage if i increase the boost (something other than buying a new engine)? thanks for any input you may have.
12-29-04, 03:02 PM
#3
Rotary Enthusiast
Join Date: Jan 2003
Location: fl
Posts: 1,255
Likes: 0
Received 0 Likes
on
0 Posts
the exhaust and the extra boosst in and of themself wont blow the engine, but not having enough fuel to compensate very well could. do some seraches on the second gen forum and think about upgrading your fuel pump, injectors, and probobly adding an safc too.
12-29-04, 06:07 PM
#5
Rotary Enthusiast
Join Date: Jan 2003
Location: fl
Posts: 1,255
Likes: 0
Received 0 Likes
on
0 Posts
well its not necissarily that expensive, but you cant do just a big exhaust on a tii and expect to be ok, you need supporting mods. you probobly dont need all of that, but the tii guys will be able to better help you out.
12-29-04, 06:36 PM
#6
(_8(|)
Join Date: Jul 2004
Location: Manhattan, Kansas
Posts: 2,034
Likes: 0
Received 0 Likes
on
0 Posts
new injectors and a new fuel pump will run you about 250-300, depending on the boost you run you shouldnt need too much extra fuel, but some would be good to be safe
Trending Topics
12-30-04, 12:21 AM
#9
Senior Member
Improving the fuel system is needed to "safely" get the power. When you bolt a big exhaust on your car you free up the restrictions on the hot side of your turbo and allow it to flow more exhaust. When you flow more exhaust you flow more compressed air (aka boost).
The problem that arises from adding the exhaust has to do with the added air (boost) and trying to keep your air:fuel mixtures safe. Detonation and blown motors is the result of having incorrect mixtures. Your fuel system is comprised of an ecu, fuel pump, fuel pressure regulator and fuel injectors. All these units have to work together to deliver the right amount of fuel at the right time. The fuel pump sends the fuel up to the fuel rail, the fuel pressure regulator controls the pressure of the fuel in the fuel line, the fuel injectors open up to deliver the fuel to the engine and the ECU decides when and for how long the injectors stay open. The ECU is the problem in this system. The ECU has maps that are based upon the stock boost settings and fuel system. If you increase the boost beyond what the ECU is programmed for it will not deliver the right amount of fuel to keep your mixtures safe. So the factory programmed an automatic shut off if the boost levels got beyond what it would safely allow. The fuel cut defender that comes with some exhaust systems removes this safety feature to allow your boost levels above stock without the fuel being cut off. So now that higher boost is allowed how do you get the stock ECU to add more fuel to compensate for the extra air? There are several ways:
1) You can reprogram the ECU so that it opens the injectors longer at the right times to deliver more fuel. The downside is that if you make changes to your car or fuel system you will have to send the ECU back for reprogramming. This can be both time consuming and expensive.
2) You can increase the pressure in the fuel rail by changing the fuel pressure regulator so that when the injectors open (still for the stock duration) more fuel is forced through them.
3) Change the size of your injectors so that when they open (at the same fuel pressure and for the same duration) they allow more fuel to flow through them than a smaller injector would allow.
The fuel pumps job in this is to deliver the volume of fuel that the system needs. If you reach the point where the fuel pump is unable to keep up with the demands of the rest of the fuel system you need to upgrade to one that will flow more.
The biggest concern with all this is that changing injectors and changing the fuel pressure regulator are like working with a kind of "best guess system" because the ECU is being "tricked" into delivering the fuel it needs. Tuning with just these basic components is expensive and time consuming without being accurate. (Ie: buy various size injectors, keep swapping them out to find out which ones work, etc.) Fortunately, there are others here who have "been there done that" that can suggest injector sizes and fuel pressures that worked for them saving you from doing all the buying and trying yourself. You still end up with a less than perfect system but it can keep you from destroying your engine.
Adding a Super AFC - which modifies the signal being received by the ECU - is another way to fine tune the amount of fuel getting into the engine. It "tricks" the ECU into delivering more fuel by intercepting the signal the ECU normally gets from it's sensors and allows you to change them to a value you want to send to the ECU. Because it's electronic you can make changes instantly and see the results - unlike the injector swapping scenario where you have to buy parts, install them and then see the results. However, you are still limited by the stock ECU and what it is able to do.
The ultimate solution would be to go stand alone (Haltech, Wolf, etc.) Yes it is more expensive to start with but if you plan on making more modifications later it's the best place to start. Why buy all this other stuff you would need to get rid of if you were planning on going with a big turbo later? Many have had their cars make more power and run much better by going stand alone. This is because the stand alone gives you finer control over your cars ignition and fueling to get your engine running closer to where it makes the most power. It may not be the easiest thing to do as it too has to be tuned but in the long run you will thank yourself for doing it. With an E6K going for $600 US it's not as expensive as it used to be. Just something to consider. Good luck!
P.S. I've completely ignored the ignition timing side of things which plays a role as your boost levels increase. This is something that a stand alone also allows you to control that the other things do not.
The problem that arises from adding the exhaust has to do with the added air (boost) and trying to keep your air:fuel mixtures safe. Detonation and blown motors is the result of having incorrect mixtures. Your fuel system is comprised of an ecu, fuel pump, fuel pressure regulator and fuel injectors. All these units have to work together to deliver the right amount of fuel at the right time. The fuel pump sends the fuel up to the fuel rail, the fuel pressure regulator controls the pressure of the fuel in the fuel line, the fuel injectors open up to deliver the fuel to the engine and the ECU decides when and for how long the injectors stay open. The ECU is the problem in this system. The ECU has maps that are based upon the stock boost settings and fuel system. If you increase the boost beyond what the ECU is programmed for it will not deliver the right amount of fuel to keep your mixtures safe. So the factory programmed an automatic shut off if the boost levels got beyond what it would safely allow. The fuel cut defender that comes with some exhaust systems removes this safety feature to allow your boost levels above stock without the fuel being cut off. So now that higher boost is allowed how do you get the stock ECU to add more fuel to compensate for the extra air? There are several ways:
1) You can reprogram the ECU so that it opens the injectors longer at the right times to deliver more fuel. The downside is that if you make changes to your car or fuel system you will have to send the ECU back for reprogramming. This can be both time consuming and expensive.
2) You can increase the pressure in the fuel rail by changing the fuel pressure regulator so that when the injectors open (still for the stock duration) more fuel is forced through them.
3) Change the size of your injectors so that when they open (at the same fuel pressure and for the same duration) they allow more fuel to flow through them than a smaller injector would allow.
The fuel pumps job in this is to deliver the volume of fuel that the system needs. If you reach the point where the fuel pump is unable to keep up with the demands of the rest of the fuel system you need to upgrade to one that will flow more.
The biggest concern with all this is that changing injectors and changing the fuel pressure regulator are like working with a kind of "best guess system" because the ECU is being "tricked" into delivering the fuel it needs. Tuning with just these basic components is expensive and time consuming without being accurate. (Ie: buy various size injectors, keep swapping them out to find out which ones work, etc.) Fortunately, there are others here who have "been there done that" that can suggest injector sizes and fuel pressures that worked for them saving you from doing all the buying and trying yourself. You still end up with a less than perfect system but it can keep you from destroying your engine.
Adding a Super AFC - which modifies the signal being received by the ECU - is another way to fine tune the amount of fuel getting into the engine. It "tricks" the ECU into delivering more fuel by intercepting the signal the ECU normally gets from it's sensors and allows you to change them to a value you want to send to the ECU. Because it's electronic you can make changes instantly and see the results - unlike the injector swapping scenario where you have to buy parts, install them and then see the results. However, you are still limited by the stock ECU and what it is able to do.
The ultimate solution would be to go stand alone (Haltech, Wolf, etc.) Yes it is more expensive to start with but if you plan on making more modifications later it's the best place to start. Why buy all this other stuff you would need to get rid of if you were planning on going with a big turbo later? Many have had their cars make more power and run much better by going stand alone. This is because the stand alone gives you finer control over your cars ignition and fueling to get your engine running closer to where it makes the most power. It may not be the easiest thing to do as it too has to be tuned but in the long run you will thank yourself for doing it. With an E6K going for $600 US it's not as expensive as it used to be. Just something to consider. Good luck!
P.S. I've completely ignored the ignition timing side of things which plays a role as your boost levels increase. This is something that a stand alone also allows you to control that the other things do not.
Last edited by soloracer951; 12-30-04 at 12:36 AM.
01-04-05, 12:18 PM
#13
you can keep the boost at the same level you currently have it with a boost controller, and then just have a catless exhaust which will add some hp
01-04-05, 01:12 PM
#14
Eats, Sleeps, Dreams Rotary
iTrader: (1)
Join Date: Jun 2001
Location: London, Ontario, Canada
Posts: 3,106
Likes: 0
Received 0 Likes
on
0 Posts
See the achieves in the FC forum for NZConvertable's wastegate porting post. Creating a monster wastegate will allow you to run a big exhaust and intake at stock boost. A considerable HP gain can be made with an exhaust at stock boost (results with my car http://www.geocities.com/jeffguilfoil/dynoresults.html). Essentially a significant, but modest enough gain can be made so that you do not require fuel mods. Later if you want to increase the boost you can use a boost controller.
Thread
Thread Starter
Forum
Replies
Last Post
