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The Terminator
Terminator Talk
2003cobra#2's 3.4 Whipple Build
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<blockquote data-quote="03cobra#2" data-source="post: 16666361" data-attributes="member: 52057"><p>Update: Part throttle drivability is fixed (for the most part).</p><p></p><p> Just to recap, I have done a lot of reading on this over the last year or so and it is definitely a problem that comes up on Whipple cars. Cars that have drive by wire can be tuned around this, not on our cars. So I pulled the blower off, and extended the vac line from the blower plate to the boost actuator so that I could access the line in the engine bay with the blower bolted to the engine. A little testing with the blower off the car shows the bypass closed nice and slow when you take the vacuum away using a .020 jet. Once I got everything buttoned back up I took her for a spin this morning. No more light switch effect in transitions from vac to boost.... nice and smooth now. In fact it's pretty remarkable how smooth the car starts, idles, and drives with stage 3 cams and a larger blower.</p><p></p><p>Couple things I noticed after putting the restrictor in. When I quick stab the throttle say in neutral the rpm's feel a bit lazy at first, probably due to the bypass valve being slower to close now. Also I can definitely tell boost comes on a bit slower, not instant. This is perfectly fine for street driving, and I suppose if I ever take it to the track I can take the restrictor out. I also ordered a few jets that are a bit larger that will speed up the closing transition, so I can play around with it and fine tune from here. Overall very pleased now.</p></blockquote><p></p>
[QUOTE="03cobra#2, post: 16666361, member: 52057"] Update: Part throttle drivability is fixed (for the most part). Just to recap, I have done a lot of reading on this over the last year or so and it is definitely a problem that comes up on Whipple cars. Cars that have drive by wire can be tuned around this, not on our cars. So I pulled the blower off, and extended the vac line from the blower plate to the boost actuator so that I could access the line in the engine bay with the blower bolted to the engine. A little testing with the blower off the car shows the bypass closed nice and slow when you take the vacuum away using a .020 jet. Once I got everything buttoned back up I took her for a spin this morning. No more light switch effect in transitions from vac to boost.... nice and smooth now. In fact it's pretty remarkable how smooth the car starts, idles, and drives with stage 3 cams and a larger blower. Couple things I noticed after putting the restrictor in. When I quick stab the throttle say in neutral the rpm's feel a bit lazy at first, probably due to the bypass valve being slower to close now. Also I can definitely tell boost comes on a bit slower, not instant. This is perfectly fine for street driving, and I suppose if I ever take it to the track I can take the restrictor out. I also ordered a few jets that are a bit larger that will speed up the closing transition, so I can play around with it and fine tune from here. Overall very pleased now. [/QUOTE]
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2003cobra#2's 3.4 Whipple Build
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