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Re: SUPERCHARGING A15
No life (a.k.a. DattoMaster)
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Quote:

B210sleeper wrote:
so how does the spring locker diff work for ya?


Not bad. The car is so rickety and rattley, that it's kinda hard to tell whats going on. When I smash 2nd, it steps sideways, and when I pull a standstill it leaves two black marks. I think I can feel it "push" a wee bit into corners.

I disagree that an s/c14 is too big. The bigger the blower the better.Once I can afford some dyno time, I'll be cranking the boost up too.

Posted on: 2006/12/8 13:25
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Re: SUPERCHARGING A15
No life (a.k.a. DattoMaster)
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that sounds like fun. needs to be stiffened up then it'll get more torque to the ground.

Posted on: 2006/12/8 13:32
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Re: SUPERCHARGING A15
No life (a.k.a. DattoMaster)
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The body? I have a six point cage to go into it.

Posted on: 2006/12/8 15:58
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Re: SUPERCHARGING A15
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Quote:

A14force wrote:

I disagree that an s/c14 is too big. The bigger the blower the better.


I was right about your setup though? 1:1 and 8 psi?

if you assume 100% engine volumetric efficiency you should be seeing 13.5 psi (even more if you adopt the 80% vol. efficiency that is usually used for 2 valve engines)

so if that's right, the blower is only about 60% efficient give or take??

Posted on: 2006/12/8 16:03
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Re: SUPERCHARGING A15
No life (a.k.a. DattoMaster)
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yup a cage'll help with a creaky body, and a lot of seam welding.

Posted on: 2006/12/8 16:26
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Re: SUPERCHARGING A15
No life (a.k.a. DattoMaster)
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Sorry for double posting this comment, but I just went and measured the pulleys on my 4AGZE, and this is what I found

Measurements:
Crankshaft = 145mm
Supercharger = 120mm
Waterpump = 110mm

Thus the SC would be way under driven with that pulley. Ok maybe with the smaller capacity engine you would see more boost.

Posted on: 2006/12/8 20:08
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Re: SUPERCHARGING A15
No life (a.k.a. DattoMaster)
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Quote:

Grunterhunter wrote:
Quote:

A14force wrote:

I disagree that an s/c14 is too big. The bigger the blower the better.


I was right about your setup though? 1:1 and 8 psi?

if you assume 100% engine volumetric efficiency you should be seeing 13.5 psi (even more if you adopt the 80% vol. efficiency that is usually used for 2 valve engines)

so if that's right, the blower is only about 60% efficient give or take??


Sort of. There are a few variables that aren't taken into account though.
One, would be that my blower has unknown K's on it. As the wear, the efficency drops.
Another variable, would be that my boost gauge is a peice of chinese sh1t. It once sufered a nasty backfire, and took to reading 2 inches of vaccuum at rest. (So I pulled it apart and screwed the needle back around)
Perhaps the most important variable that has been overlooked, is the question of "what IS boost"?
Boost is only a measure of FLOW RESISTANCE/RESTRICTION between the pump, and the head of the valve. The local cylinder head guru told me that they id a blown V* race boat motor. It made 7psi. They swapped the heads for some real kick ass ones, and the boost fell to 5psi. Boost only accrues when the charge is slowed down and allowed to build up in the intake tract. The easier the flow can enter the cylinder, the less boost will there be.
Doesthat make sence?
I'm not saying that my engine is free flowing, but the bigger intake ports on my gx head probably flow better than the standard a15 head my old motor had.

Posted on: 2006/12/9 8:01
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Re: SUPERCHARGING A15
No life (a.k.a. DattoMaster)
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Quote:
Boost only accrues when the charge is slowed down and allowed to build up in the intake tract. The easier the flow can enter the cylinder, the less boost will there be.


It does in a sense. It indirecly translates to using the same SC at the same speed on a big or small engine, where it will boost higher on a smaller engine and lower on a bigger engine.

I've seen a guy go from a 60mm throttle body to a 75mm and back again, because he car became simply undrivable in town. The lag became big, and when boost eventually built up, it came on so strong hat the car kept going sideways. Even on the 4A-GZE engine such as the one I'm fitting, they decreased the port sizes at some stage, and the power went up...

Posted on: 2006/12/9 8:13
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1200 GX Sedan
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4AGE 20V NA

Old
4AGZE 16V turbo
196.5KW/283NM
800m - 200km/h
400m - 12.3s
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Re: SUPERCHARGING A15
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It makes sense, your on the money. Its also why cars with big plenums/ intercoolers will take longer to get boost....simply need more air to fill the extra volume..

Does a 2 valve head really have 80 % VE??? whats the VE for a 4 valve head??? and how about a 5 valve head???

As for throttle bodies...thats to do with driveability...a big throttle body becomes a big on off switch so the engine becomes hard to control.

Posted on: 2006/12/9 8:17
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Re: SUPERCHARGING A15
No life (a.k.a. DattoMaster)
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those VE's are ideal, part of what helps is exhaust scavenging, race engines can hit over 100% at the right rpm.

Posted on: 2006/12/9 9:21
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