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Old 06-16-2006, 12:30 AM   #31
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how would i go about stopping the bypass from dumping untill 22 psi?
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Old 06-16-2006, 12:33 AM   #32
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Again, the PCM will never know how much boost you have. The only reason the PCM will dump is if:
Knock
It thinks too much air is passing the MAF (maybe, I haven't confirmed this yet)
While shifting


You CANNOT program anything or tweak anything to make the wastegate hold till a certain pressure level, because it simply doesn't know what pressure is present.
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Old 06-16-2006, 12:37 AM   #33
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Quote:
Originally Posted by J Wikoff
Again, the PCM will never know how much boost you have. The only reason the PCM will dump is if:
Knock
It thinks too much air is passing the MAF (maybe, I haven't confirmed this yet)
While shifting


You CANNOT program anything or tweak anything to make the wastegate hold till a certain pressure level, because it simply doesn't know what pressure is present.
High IAT temps (I recall something about this)
Lean fuel condition
Fuel cutoff RPM is reached
High trans temp

Quote:
Originally Posted by ZCRX87
how would i go about stopping the bypass from dumping untill 22 psi?
22psi? With what? The magic super-duper amazing boost producer? You CANNOT make an M62 produce that much boost. BARELY half that. Even if you could, you would produce so much heat that you'd melt a piston and destroy your engine.

We're not busting on you here, but we need to make sure you understand this. I suspect someone is filling your noggin with fantasies and misinformation.

John Wikoff (above) and I are perhaps the two most knowledgable Series 1 L67 guru'* on this Forum.

If you want 22 psi of boost, go TURBO, with a bigass intercooler and a custom PCM. Beef up the entire bottom end and the transmission. When you're done spending that $15,000, we want video.

You need to quit talking about boost pressure and start thinking about how to increase FLOW through the top end, so you will see a DECREASE in boost pressure. That means you're actually using it and getting the best out of it.

Don't fall prey to the ricer-mentality of 'more boost!'. This isn't a Turbo 4-banger rice-bomb.
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Old 06-16-2006, 12:48 AM   #34
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I don't think 92/93 monitor tranny temp, do they?

You won't be able to work 22 psi into your tune. You could, maybe work the side effects of 22 psi into your tune. But like Bill said, keeping that air charge cool is A MUST for that much pressure. You'd need a tiny spark plug gap, lower the compression ratio (is using 5 layers of head gasket an option? ), and maybe one of those bigass newer roots type blowers.
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Old 06-16-2006, 12:55 AM   #35
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92/93 trannies have a thermister that switches states at a pre-set temp. When that switch is made, you go into limp/boost dump.
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Old 06-16-2006, 01:23 AM   #36
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That is something I didn't know.
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Old 06-16-2006, 08:39 AM   #37
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The PCM doesn't know (92/93) WHAT temp the trans is, but the PCM does know that it has reached a 'critical' temp. I saw the thermistor personally during my trans rebuild on the Zilla.

This was also discussed recently in Sandrock'* swap topic in 92-99. Don and I went through the 92, 93, and 95 FSM'* to determine the difference a couple weeks ago.
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Old 06-16-2006, 01:37 PM   #38
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Well, a big old school 6-71 should get your boost that high but would look odd sticking up through the hood; not to mention the custom fabrication to get it on the engine.

Many people look at the pro racers and see the astronomical boost levels and think "that is what I need". The pro racers are running high boost pressures because they have rules restricting engine displacement, throttle diameter, etc... They use the high boost as a way around the restrictions. A turbo WRC car has a big intercooler and water injection to keep intake temps under control. Top fuel dragsters only need to run for 5 seconds and are rebuilt between rounds.

Hourly rebuilds and intercoolers big enough for a semi-truck are not practical for the street. Carefully ported heads, manifolds and a good exhaust are. (less expensive too)

If we think about how fast we can flow air through the engine instead of how hard we can slam it in we will get better results and longer engine life. (and ricers in the mirror)
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Old 06-16-2006, 07:53 PM   #39
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Would the rotors of an M62 even be able to withstand the RPM it'd take to produce that much boost? Or more importantly, would they be able to expand enough from the heat and still have clearance between themselves and the case? Would the bearings hold? Maybe he'* thinking of using just the L67 longblock and... a Whipple 2.3L or a Lysholm 2300AX?
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Old 06-16-2006, 08:05 PM   #40
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A screw type supercharger would be more compact than an x-71 but would still require very expensive fabrication work to mount it to the engine.

The Eaton rotor groups are tested to 20000rpm The ~14000rpm design limit is based on diminishing returns from heat. (The added heat hurts you as much or more than the added air helps.)

As far as not flying appart is concerned, I don't know if Eaton or Magnuson have tested beyond 20000rpm. The test speed is far enough past the rated speed to make it point less to go higher, unless they just like destroying stuff.
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