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Talk me into a clutch

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Old 03-13-2018, 02:51 PM
  #21  
Cux350z
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Old 03-13-2018, 03:48 PM
  #22  
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Originally Posted by Cux350z View Post
You can get the clutch for around 2200 + shipping, import fee and nissan parts. 2400ish delivered.

As for the website...guess yall are more about glitz and glam. I listed the 3 pages you needed to know.

Like i said..price, holding power and driveability....pick 2.

People dont seem to understand what it takes to make a driveable car with big power. 3k clutch, 3k in fuel system, 3k in ECU and we have not even bolted on a turbo.
Yup, glitz and glam. Isn't that what the interwebs are for? Laff....

But your last statement hits it on the head. Making engine power is easy. Making it all work together is the hard part.

Jeeesh, when I think about it, I've now owned around 8 turbo cars (only two were Zs and not even 33s), half of which were tweaked, tuned, built in some way, shape or form and I don't consider myself even a half an expert. I have learned though, that when you find someone/some shop that knows what they're doing, it's worth the extra money you need to pay 'em because they are FEW and far between.
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Old 03-14-2018, 07:05 AM
  #23  
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Originally Posted by MicVelo View Post
Well, this is the Pandora's box enigma of running a turbo car.

First, look at the benefits of a LIGHTER FLYWHEEL: less weight hanging off the crank and therefore easier to rev and get you "into the power band".

Problem with that is that because it takes the load off the engine, the engine also LOSES revs faster than a heavier flywheel due to inertial forces. (You'll see why this is important below.)

Now compare that to how a turbo behaves. A turbo engine by itself, car out of gear, can be revved to 5k rpm unloaded and not build a quarter pound of boost pressure. Why? Well, never mind airflow dynamics for a second but this has to to do with pressure deltas INSIDE and OUTSIDE the engine, particularly on the intake side. Free revving barely budges a vacuum gauge yet, when in gear, under acceleration, you can watch the vac drop THEN as the turbo kicks in, go from negative pressure to positive.

That's because a turbo requires a load on the engine to work well. (Highly oversimplified.)

So, you drop some of the load off the engine and the turbo takes longer to build boost. Note I didn't say spool up. A lighter flywheel does little to change the spool up but to actually build the boost pressure, yes, this CAN AND WILL BE affected.

Also something to keep in mind is a lightened flywheel - as mentioned - drops revs in off throttle conditions quicker than a DMF or heavier single; thereby introducing more pronounced boost gaps (the loss of boost when shifting) requiring the turbo to build boost back up each time you shift. With a DMF or heavier single (up to a point) helps - through inertia - to keep load on the turbo, shortening the boost gaps.

This can have a big effect on power delivery. Not so much on a dyno because this isn't too much of a concern as the boost gaps are not so noticeable when you're pulling a single gear to get max power and torque readings. But driveability.... you will notice how "not smooth" it is as you row the gears up towards top gear.

Does this mean a HEAVY flywheel is "better"? No, not necessarily. The key is carefully matching the turbo and the clutch/flywheel assembly. There is an optimal weight for it given the type/size turbo and how it builds power. Exceed that weight or go too light and the turbo won't run as efficiently and will hit a point of diminishing returns - the base and height of the power curve as it were....
Very interesting... I would imagine the same would hold true for a centrifugal SC?
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Old 03-14-2018, 10:30 AM
  #24  
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Originally Posted by LexD View Post
Very interesting... I would imagine the same would hold true for a centrifugal SC?
Great point!

While I don't want to take away from CK's original posit regarding drivetrain related to FI, will say a few things speaking in generalities...

A centrifugal supercharger - like a Vortech on our Z cars for example - doesn't have QUITE as much issue making usable boost throughout the rev range as a turbo because it is mechanically (belt) driven and not as dependent upon load to build boost; therefore has the capability of making boost slightly lower down in the rev range than a turbo.

Related side note: Comparatively, a typical centrifugal S/C doesn't have the oomph that a screw-type supercharger produces down low. (But can.....see next-to-last paragraph.)

So, the answer to the question comparing a "traditional" turbo's characteristics to a centrifugal supercharger (which is essentially a belt driven turbine) is "Wellll, yes and no." Yes, there is some latency in achieving the boost but no, due to the mechanical nature of a centrifugal S/C, boost is available earlier than a turbo and features a lot more linear torque curve than a typical turbo application on a given/equal engine.

However, as with ANY FI (or NA FTM) application, there's always a "way around" through tuning, selective hardware matching, and of course, a goodly knowledge base of all.

Natural question to follow that is, "Which is better?" Ehhhhhh..... not gonna take sides on that one because both a turbo and a supercharger can both make as much power and torque as the other depending on how it's set up (there's that "proper matching" thing again). That is, a supercharger with the correct amount of "trim" (sizing and drive speed) can be made to produce just as much power and produce a nearly identical torque curve as a turbo. And vice versa.

So in the end, which to choose? Just depends on the type of power delivery characteristics you're seeking and how it's going to be used. Down low with a linear torque curve all the way up the tach limit (like a drag application) or max power in the mid-upper ranges (long course racing) or <you choose your poison based on the application>.

I note that there are a couple of turbo and supercharger threads current. Suggest some reading there to see how this all plays out in the real world.

Last edited by MicVelo; 03-14-2018 at 10:31 AM.
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Old 03-14-2018, 11:20 AM
  #25  
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Take away all you want boys. You know I'm down for the dicusssion rather than the topic.

If someone has anything else to input I'm sure it can be posted in the midsts of the new topic.
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