Turbo; JH or PL?

[tyrone27 at gmail.com (Derrick floyd)]

ok guys I just posted a Compressor map starting point for the 2.0 16v motor
on VW Vortex under Forced Induction.  its not perfect but its a good
starting point for people looking to turbo there cars.

On 1/8/07, Tonee Northam <pb3vr6@yahoo.com> wrote:
>
> I really don't mean to interupt, Dan and Larry, but have you guys ever
> ridden in Scott Kraus's yellow mk2?
>
>   No turbo, and was crazy fast.
>
>   My point being, If I have one really, what can you do to the engine to
> get it to produce great hp/tq numbers without a turbo?
>
>   What are the alternatives?
>
>   Thanks Guys,
>
>   Tonee
>
> LEF <rocco16@sbcglobal.net> wrote:
>
>
> Dan sez:
> If you're running 15psi, ......The gain you will see from an incremental
> increase in boost will be less than the gain you will see from that same
> increment if you're starting at 5 psi.
>
> Larry sez:
> Agree. Let's take it to extremes to illustrate your point: if you are
> running 1psi and increase it by 1psi (to two psi), you have increased your
> boost by 100%. If you are running 100psi and increase it by that same 1psi,
> you have increased your boost by only 1%. However, this doesn't necessarily
> mean the engine is making less hp by going from 100psi to 101psi....just
> that the percentage of increase is less.
>
> At some point, turning up the boost simply produces more heat and no more
> power..... and as a result although the pressure in the cylinder is high
> it's density is low due to it's high heat so you're actually getting less
> mass of air into the cylinder.
>
> You're saying that at some point, the more air I put into a given volumn
> (increase the pressure), the less air I'm putting in?
> Hmmmmmmmmmmm...I need to chew on that one for awhile. :)
>
> One example that comes to mind is the Formula 1 McLaren Porsche turbo of
> 1985. Obviously an extreme example since these were 1.5L engines running
> in the 45 psi boost range and making ~900 Hp. In those days boost was not
> limited during qualifying and they were simply removing the wastegates for
> maximum boost. Porsche tried this, yet when they ran without wastegates the
> cars were no faster. Which just illustrates my point that "just turning up
> the boost" has it's limits even for an out-and-out race engine.
>
> This begs the question of whether the failure to drop lap times had more
> to do with too much power rather than no net increase in power. You CAN
> absolutely reach a point where more power gains no net improvement in lap
> times. But we aren't talking about dropping lap times, we are talking about
> increasing power.
> BTW, if more boost is counterproductive, why did the F1 cars turn up the
> boost for qualifying????? That statement above doesn't support your theory,
> it supports mine....."turn up the boost!!!" :)
>
>
>
> So, when you say just turn up the boost and not bother with other
> performance enhancements I think you need to be specific about the boost
> levels where this is actually true and be aware of the fact that the lack of
> other performance enhancements will limit the boost attainable to a lower
> level than if you treat the engine as a system and size all the components
> appropriately.
> The F1 guys apparently believed that just "turning up the boost" was the
> path to more hp, and I doubt they changed cams, ported & polished, put
> different exhausts on, etc. for those qualifiying runs. Were they just
> guessing?
>
> I'm sorry if you feel this is a personal attack. It's not intended that
> way. I just think that your theory is true only to a limited extent and that
> extent ought to be addressed.
> Didn't say it was a personal attack, did I? I said it was getting close to
> it. :)
> Fair enough, as I think the same of your theory. We're even.
>
>
>
>
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