Boost Question

[WizardBlack]

I'm sure Tony knows the difference between a RRFPR and a plain jane 1:1 like the Aeromotive models, etc. Definitely get your A/F ratio out of the tens. That'll really slow you down. Likewise, get the leaks around the injectors fixed or you'll have tune/spool issues as well.

 

For leak testing, here is what I do. Find a piece of pipe that fits into the coupler hooked up to the inlet of your turbo. Weld a plate across one end of it to seal it off. Drill a hole in the plate and weld a compressed air fitting onto it that fits your air system. Hook up a REGULATED compressed air line that has been turned down to zero. Slowly turn it up to about 1.5X your estimated highest boost pressure. You want to go higher than your boost pressure to try to help simulate heat on the couplers and the surge of force as the turbo spools. Leave the throttle alone. Don't install any blockoff plates, etc. You'll notice a bit of hissing if there's any overlap in the cams and you hit the right spot in the timing. Otherwise, move your ear around everywhere really close to the engine and piping, etc. This should root out any leaks. Be ready; if the couplers aren't tight enough, they will blow off and when they do, it's pretty @$#@ loud.

[HB280ZT]

Well I just took the car out with a friend watching the boost guage and he is seeing the same thing my datalog is tell me. The car will boost to 6 psi when the petal is pushed to the floor then go up to 15 psi as the rpms increase. He has never seen anything like that before.

 

So my next item to try is to replace the waste gate actuator and see if that changes anything.

 

As for any pressure leaks I have them all fixed except for the injectors and the TPS. I will be replacing the intake, I hope in a few weeks then I will replace all of the injector seals. Where to get them? I am running 11mm 460 cc injectors and a palnet fuel rail.

 

Thanks for the help.

 

HB280ZT

[Pyro]

I'm sure Tony knows the difference between a RRFPR and a plain jane 1:1 like the Aeromotive models, etc. Definitely get your A/F ratio out of the tens. That'll really slow you down. Likewise, get the leaks around the injectors fixed or you'll have tune/spool issues as well.

.

 

aeromotive fpr has a 1:1 ratio.

[HB280ZT]

Well I just got back from another datalog run and it is running much better now. I replaced the waste gate accuator and apparently that fixed the problem of a slow boost to full boost. I will look at the datalog in a bit as I am off to an appointment. Will keep you all posted.

 

HB280ZT

[HB280ZT]

Well I analyzed the datalog and it appears that I get boost to the limit of the waste gate actuator, 8 for old one and 15 for new one. Then they allow boost to increase until the MBC engages.

 

So the million dollar question is how do the people who use boost controllers get the waste gates to not open at a lower boost level??

 

Also the afr's are looking pretty good. I was seeing 21 psi of boost with afr's between 11.5 and 10.7. I know that is still a bit to low but there is still room for improvement.

 

Hb280ZT

[mobythevan]

So the million dollar question is how do the people who use boost controllers get the waste gates to not open at a lower boost level??

 

Are you sure the boost controller is not leaking?

[HB280ZT]

Well I guess that could be a problem however, I have used 2 different waste gate actuators (8 and 15 psi) with a manual boost controller and both let go at there set pressures and then went on to increase boost up to a set value determined by the manual boost controller. To me the boost controller is working just fine however the pressure in the system is over coming the waste gate actuator spring and allowing the waste to open some. So like I asked how do you stop this from happening with a boost controller?

 

I am just going to remove the manual boost contoller for now and just run off of the waste gate actuator.

 

HB280ZT

[WizardBlack]

aeromotive fpr has a 1:1 ratio.

 

That's what I said.

[jc052685]

Well I guess that could be a problem however, I have used 2 different waste gate actuators (8 and 15 psi) with a manual boost controller and both let go at there set pressures and then went on to increase boost up to a set value determined by the manual boost controller. To me the boost controller is working just fine however the pressure in the system is over coming the waste gate actuator spring and allowing the waste to open some. So like I asked how do you stop this from happening with a boost controller?

 

I am just going to remove the manual boost contoller for now and just run off of the waste gate actuator.

 

HB280ZT

 

 

 

i believe thay are suposed to do that. Otherwise the boost would not level off, it would keep climbing. That is why they call it a boost controler, because it controls the boost.

[HB280ZT]

jc052685, I think you misunderstand what I am saying. To me a boost controller should not allow boost to get to the waste gate actuator until it hits it set value. Well my controller was doing just that. However the waste gate actuators spring was being overcome by the exhaust gas at 8 psi of boost, I was running 15 psi of boost at that time. When I upgraded to my 15 psi actuator it was also overcome by the exhaust gas pressure when I was running 20 psi of boost.

 

So that being said how do you resolve the waste gate actuator spring issue when using an adjustable boost controller?

 

HB280ZT

[mobythevan]

Sounds typical to me. I made a test bench where I could add pressure to the wastegate on both the diaphram input and the exhaust input so I could model any system pressures. When you do that and you assume the exhasut pressure equals boost pressure (which is what the manufacturers of wastegates assume for setting up initial spring values) then you will find that the smaller springs open under exhaust pressure. Like you see an 8lb spring will open under say 12 pounds of exhaust. The answer is simple, you have to run the wastegate spring that is closest to the boost value you want, this was mentioned earlier in the thread.

 

Now, an exception to that is my talon where I run the 9psi factory wastegate, but run up to 18psi with MBC and I don't see any problems with it pushing open from exhaust pressure.. I think it is due to the smaller area of the wastegate puck, so 18psi on a tiny WG puck like the talon is not much total pressure. However 18psi on my 60mm wastegate puck/valve is much more total pressure that the spring has to hold.

 

Begs the question, what wastegate are you using(internal or external)?

[ktm]

If you read one of my initial repsonses to your question, I clearly stated exhaust pressure as a possible culprit and the fix. The exhaust gas pressure can exceed boost pressure, especially at 15 psi. I fixed this problem (running a 15 psi WG at 22 psi) by using an external spring on the WG actuator arm.