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Boost by gear.

MetalSpikeRacing

MetalSpikeRacing

Experienced Member
Joined
20 March 2009
Messages
1,348
Location
Toronto/Cancun
Hey guys, I want to get the car tuned so I can have boost/power by gear, but I am a little cumfused, so here is the equation:

I want first gear at 3psi/290whp
Second gear at 6psi/350whp
Third gear and up 8psi and hopefully anything north of 400whp.

And here is the question:
What size spring should I install in the wastegate??

I have a 3psi spring in it right now, you guys think the spring would multiplie it's rate almost three time to reach my final 8psi? Or how is it work?

The wastegate it's a 46mm pressicion unit, the boost controller is the AEM tru-boost and it will be managed by an AEM EMS.

Thanks in advance,

-MSR
 
Why would you do that and how? If you have an automatic, then you probably shouldn't be boosting much. If you don't have an automatic, then the car doesn't know what gear it's in, unless it's in neutral or reverse. What inputs does the EMS have to control boost to different levels?
 
if you have a standalone you can definitely do this. What I would do is get the car tuned first and then if you have excessive wheel spin you can have the boost by gear set up. I dont know your particular wastegate but if you have a boost controller on a standalone the 3 psi spring wastegate should should be ok.. Get the car tuned first and then decide if you want to go that route..... Good luck :biggrin:
 
MetalSpikeRacing said:
Hey guys, I want to get the car tuned so I can have boost/power by gear, but I am a little cumfused, so here is the equation:

I want first gear at 3psi/290whp
Second gear at 6psi/350whp
Third gear and up 8psi and hopefully anything north of 400whp.

And here is the question:
What size spring should I install in the wastegate??

I have a 3psi spring in it right now, you guys think the spring would multiplie it's rate almost three time to reach my final 8psi? Or how is it work?

The wastegate it's a 46mm pressicion unit, the boost controller is the AEM tru-boost and it will be managed by an AEM EMS.

Thanks in advance,

-MSR
Click to expand...

Like brian campbell said....if you have a stand alone and boost controller, you will not neet to change the spring in the wastegate. If you do not have a boost controller installed the wastegate will only allow the rated spring amount of boost. For boost by gear option you will need a solenoid. Examples would be AEM, Haltech, and even GM. IMO a tune is mandatory so that you do not damage your motor.
 
Thank you guys, I just wanted to confirm that the 3psi spring will be able to be "stretch" to reach the final 8psi.

Yeah, the tru-boost comes with a AEM solenoid that can be wire into the EMS.

I just wanted to make sure that I have the right spring in the WG, because once you bolt up the turbo kit, you have to bring everything out again if you want to change the spring.

Thanks,

-MSR
 
Since you have AEM, you might want your tuner to use the speed variable boost feature on AEM.
My tuner successfully used it to prevent uncontrollable wheel spin that was occurring in lower gears.
I found that larger and stickier tires are also helpful in reducing wheel spin and minimize the need to use speed/gear variable boost.
 
MetalSpikeRacing said:
Thank you guys, I just wanted to confirm that the 3psi spring will be able to be "stretch" to reach the final 8psi.

Yeah, the tru-boost comes with a AEM solenoid that can be wire into the EMS.

I just wanted to make sure that I have the right spring in the WG, because once you bolt up the turbo kit, you have to bring everything out again if you want to change the spring.

Thanks,

-MSR
Click to expand...

A 3 psi spring in the wastegate is fine for your use. You do not need to use the Tru-Boost gauge, instead, you can use a separate solenoid valve like this:
http://www.scienceofspeed.com/produ.../ScienceofSpeed/wastegate_solenoid_valve_kit/

However, if you already have the gauge, that would be fine as well - you'll allow the EMS to control the solenoid, not the gauge. You will wire the fused 12V constant to the solenoid valve, and the ECU will pulse the ground to actuate the valve. The spring doesn't stretch, rather the solenoid valve will modulate pressure going to the wastegate to control the pressure the turbo is making.

cheers,
-- Chris
 
MetalSpikeRacing said:
I dont want excesive wheel spin.

-MSR
Click to expand...

I don't see the point of 3psi in first. Bob K has 6-8 psi in first and it doesn't have excessive wheelspin. CTSC do 6psi in first. I would at least go with 6psi and then go up to your max boost in 3rd.
 
I did have some wheel spin coming out of the pits when the car was stock, I beleave that adding 6psi on first gear will put the car roughly at around 350-370whp on a 40R., which would be just good for nothing.


-MSR
 
Last edited:
Well if variable boost is programmable and adjustable, set it up the way you stated above. Then when you have some track hours, you can make the necessary changes. That being said, no way you are going to spin tires at 3psi. Remember tire spin usually begins at gear change. You are not producing anywhere near 290rwhp at 5000 rpm's which is usually were wheel slip begins either as boost maxes out and or VTEC kicks in.

Sometimes making things complicated is more expense and trouble than it is worth; and reliability suffers. That's why I just run a plain old big journal turbo and AEM F/IC and manual boost controller and 3lb spring. But then again, I don't track my car...........I just embarrass Corvette/BMW/MB AMG owners. :cool:
 
I had set my SC boost up so it changes with RPM. So I would run 10 PSI at the start and at 3900RPM it would go up to 16PSI. This was on my TEC-3.
 

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