Wastegate configuration options with electronic boost controller

[UnleashedBeast]

Good afternoon all,

I have a techie question for those who are wastegate knowledgeable. Recently, I purchased a Turbosmart eBoost2 electronic controller for my twin turbo setup. The installation manual has presented me with two options using a single solenoid.

My goal is to learn the pros and cons of both configuration methods and to also learn about the effect of referencing the gates at the compressor (pre-intercooler) and at the manifold (post throttle body).

Configuration #1 is simple:


Configuration #2 is a bit more involved, but not a big deal at all:


As stated above, my two questions are:

• What are the pros and cons of each configuration method?
• What are the differences between boost reference points? *compressor (pre-intercooler) vs. manifold (post throttle body)*

Ultimate goal is to use a lighter gate spring to run 8-10 PSI on pump gas. Then use the boost controller to increase boost up to 12-13 PSI on race gas. When the built engine is installed, I will use the controller to increase to ~20 PSI. If it's true an electronic controller can only double the pressure from the base spring rate of both gates, I may have to keep the 10 PSI springs in.

 

[Shaun@AED]

Troy,
Think about a situation where you lose one of the boost lines to the waste gates and what the effect would be.

In both of the above scenarios the Boost controller is either set to open the waste gates by adding boost, or offset bottom port boost by adding boost (pressure differential between top and bottom of waste gate diaphram) this would mean you have a very stiff Waste Gate spring and as you decrease pressure via boost controller (lower duty cycle) you raise boost in scenario one, or raise duty cycle in scenario 2 to raise boost. Both of these setups run a stiff waste gate spring (whatever your max would be, lets say 20) and use the controller to reduce pressure. Lose a line to the waste gate lower port and you will get full 20psi boost, or whatever the gate is set for.

I prefer to use waste gate spring only for 'low boost' with no boost reference on the waste gate, then only use the top port with a boost controller. This way, if you lose a boost line you do not over boost.

 

[UnleashedBeast]

Thank you Shaun.

Absorbing what you posted, that means venting the bottom (side) port of the wastegate to atmosphere, which would require a much lighter spring to achieve desirable "low boost" scenario.

Then, you use the top port of the waste gate for the boost controller solenoid to "add" additional pressure to the top of the diaphragm, effectively making it require more exhaust pressure to open the gate. This increases boost with a fail safe in case you lose a vacuum line. The gate will default to the light spring pressure only.

Question, is there a maximum increase percentage over spring tension only that boost can be increased? For instance, gate pressure (low boost) is set for 10 PSI. Is 100% increase feasible (increased to 20 PSI using the controller)?

 

[Doug1227]

I bought my Eboost2 used and hooked it up the same as the previous owner. Here's how he had it done.

 

[cb900f]

Thank you Shaun.

Absorbing what you posted, that means venting the bottom (side) port of the wastegate to atmosphere, which would require a much lighter spring to achieve desirable "low boost" scenario.

Then, you use the top port of the waste gate for the boost controller solenoid to "add" additional pressure to the top of the diaphragm, effectively making it require more exhaust pressure to open the gate. This increases boost with a fail safe in case you lose a vacuum line. The gate will default to the light spring pressure only.

Question, is there a maximum increase percentage over spring tension only that boost can be increased? For instance, gate pressure (low boost) is set for 10 PSI. Is 100% increase feasible (increased to 20 PSI using the controller)?

I did mine with Diagram 2. You can turn the EBoost down to a duty cycle of 0, and sit on wastegates. I have very low spring pressure (4.5psi) in mine. I also have this setup as SP1. So when the car starts up, it defaults to SP1 (Wastegates), SP2 added about 35% duty cycle which is 7.5 psi. SP3 is 50% duty cycle which is right at 10psi.

So driving, I can quickly swap between boost groups. If I need that extra bit, I just open the cut-outs for an additional 1psi.

 

[Shaun@AED]

Thank you Shaun.

Absorbing what you posted, that means venting the bottom (side) port of the wastegate to atmosphere, which would require a much lighter spring to achieve desirable "low boost" scenario.

Then, you use the top port of the waste gate for the boost controller solenoid to "add" additional pressure to the top of the diaphragm, effectively making it require more exhaust pressure to open the gate. This increases boost with a fail safe in case you lose a vacuum line. The gate will default to the light spring pressure only.

Question, is there a maximum increase percentage over spring tension only that boost can be increased? For instance, gate pressure (low boost) is set for 10 PSI. Is 100% increase feasible (increased to 20 PSI using the controller)?

There is no maximum with the light spring / top port only setup assuming back pressure in the exhaust is not excessive.

If you set it up as described in the instructions, maximum boost achievable would be waste gate spring + a lb or 2 if you plumb the top port from the compressor and bottom port post intercooler where pressure would be slightly reduced.

 

[slagburn]

I've tried lots of different configurations, 2 4 port solenoids seems to have the largest controllable range and has no problem hitting 3x or above WG spring pressure.

 

[Doug1227]

Like I posted? I think mine have the factory wastegate springs in them (5psi?), but I'm putting it on the dyno next week and will most likely setup several boost settings peaking around 15psi. Think I'll have any issues?

I've tried lots of different configurations, 2 4 port solenoids seems to have the largest controllable range and has no problem hitting 3x or above WG spring pressure.

 

[cb900f]

Like I posted? I think mine have the factory wastegate springs in them (5psi?), but I'm putting it on the dyno next week and will most likely setup several boost settings peaking around 15psi. Think I'll have any issues?

You will be pretty high on the duty cycle. You might want to put a larger spring in there if you want to be certain to get 15psi.

 

[Doug1227]

Which spring should I buy? They have a 7# "middle" spring and a 7# "outer" spring.

 

[cb900f]

Which spring should I buy? They have a 7# "middle" spring and a 7# "outer" spring.

Which gates do you have?

 

[UnleashedBeast]

Assuming configuration #1, am I correct to say.....

Referencing boost post throttle body will make the engine produce 1-2 more PSI than if it were referenced pre-intercooler, due to the pressure drop after the intercooler? Less pressure on the bottom port of the gate will have less assist to actually open the gate, therefore creating more boost with the same spring.

Correct?

 

[Doug1227]

The 40mm Turbosmart CompGate's that come with the base Hellion Twin kit. Sorry for the thread hi-jack OP.....

Which gates do you have?

 

[cb900f]

The 40mm Turbosmart CompGate's that come with the base Hellion Twin kit. Sorry for the thread hi-jack OP.....

From the manual:

(Link for your verification I pulled up the right product)
http://www.turbosmartusa.com/wp-content/uploads/2011/11/TS-0505-1001_Compgate40_MAY_12_rev_2.pdf

I'd run the 7psi middle spring. Should be Brown or purple.

 

[wakebum2507]

I have mine running as follows, single turbo, dual wastegates:

compressor housing on turbo line running to the solenoids. From solenoids to the top port on each gate, that will allow me to use pressure from the housing to add pressure to the top of each gate, adding boost.

tapped my charge pipe, right before the TB (boost only since its before the TB). This line goes to my MAP sensor (digital boost reading on boost leash) as well as the BOTTOM ports on my wastegates for true boost, instead of reading from the compressor housing, which will be marginally higher in some applications.

recap: top ports to add boost coming from compressor housing via solenoid, bottom ports to open the gates coming from charge pipe, boost only reading.

precision likes their gates to see only boost, so that's why I pulled from the charge pipe, rather than my vacuum block.

 

[Doug1227]

Excellent. Thanks. I went to the their site and looked at the springs available, but didnt' see the WG manual. Got it. I'll order (2) 7# middle springs so I'll have them on hand just in case.

 

[badbiach]

I bought my Eboost2 used and hooked it up the same as the previous owner. Here's how he had it done.

View attachment 40411

This is exactly how I have mine hooked up. I also have the very light springs that came with my Hellion kit. SP1 value set to 0, I see 4.5---5.5 psi based on DA that day. I have had ZERO problems turning the SP value up to 10 psi, 15psi, or 20psi. The selinoids that came with my Eboost 2 seem to be VERY dynamic. More SP value, more boost, every time. I have not found the limit of the light 4.5lb spring. Every car will vary. Your SP set at 38 may produce 15psi, and another car may produce 12 psi using the exact same spring. Point being, I wouldn't go with a stiff spring for fear of not being able to accurately turn it way up.

 

[wakebum2507]

so did I understand this correctly:

some of you are not referencing the bottom ports at all, so the gates would only open when enough pressure is achieved, pre turbo?

i guess if you did that, you could run a super light spring.

i was just always under the impression you HAD to reference the boost to the bottom port of the gates from somewhere in order for them to open.

 

[cb900f]

so did I understand this correctly:

some of you are not referencing the bottom ports at all, so the gates would only open when enough pressure is achieved, pre turbo?

i guess if you did that, you could run a super light spring.

i was just always under the impression you HAD to reference the boost to the bottom port of the gates from somewhere in order for them to open.

No, my bottom ports are connected to the TB.

 

[badbiach]

so did I understand this correctly:

some of you are not referencing the bottom ports at all, so the gates would only open when enough pressure is achieved, pre turbo?

i guess if you did that, you could run a super light spring.

i was just always under the impression you HAD to reference the boost to the bottom port of the gates from somewhere in order for them to open.

I don't think they are meaning that. In order for you to have any "control" over the spring in the gate, yes, you must control both the top of the diaphragm and the bottom. I have seen some controllers that simply play with the signal that goes to the bottom and doesn't do anything to the top, but I think these are mostly the older manual type controllers. There are tons of ways to plumb these, but I have had reliable success going from turbos to bottom port of selinoids, then top of selinoid exit to top of gate and bottom of selinoid exit to bottom of gate. My "boost reference" for the actual eboost2 controller is simply post intercooler, pre TB. One selinoid can operate 2 gates, but a turbo guy that is much smarter than I suggested to use 2 selinoids for 2 gates.