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Subject:
Team3S Digest V1 #246
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Team3S
Digest Sunday, August 1
1999 Volume 01 : Number
246
----------------------------------------------------------------------
Date:
Sun, 1 Aug 1999 00:37:19 +0200
From: "R.G." <robby@freesurf.ch>
Subject: Re:
Team3S: Dyno/eRAM..., eRacing responds...
Mark, some "small questions"
:
>We have tested a MR2 turbo with 16psi boost. It produced mirror
image
>baseline runs, and the eRAM gained peaks of 10 hp at two different
points
>on the dyno run. (2 liter )
Due to the dyno
sheet the car seemed to slip a lot on the rolls. Or why else
is the the power
curve looking that strange ?
>Now to answer you question regarding a
hair drier in series with another
hair dryer. Lets just say it
is
>generally accepted axial fan flow theory that says that two
equal flow
fans
>in series willproduce double the pressure a the same
flow rate. Two fans in
parallel will
>produce double the flow rate and
the same pressure.
Yes, I answered my question already as I compared this
with two pipes of
water (althoug water is not compressable but it works) :
Let's assuming to
have two pipes with 0.56" diameter and the same lenght. The
water weight in
the pipes is 1 pound each. The pressure on the bottom of each
pipe is
therefore 1psi.
1. If you put the second pipe onto the first
we'll get then 2psi (double the
amount of water) = serial hair dryers
:)
2. If you put both pipes side by side onto another pipe with double
the
surface we will have still have 1psi but double the flow.
>The
air flow going into the mass flow sensor and then to the turbo is
now
>going at a certain % faster due to the turbo. (ie 420 cfm on a 15 psi
2
>liter vs 212cfm NA)
But air speed is not changing after the
turbocharger. This figure is given
by boost and the amount of air the engines
displacement (and some constants)
I agree that the more the air is
pressurized the more air speed we have in
the pre-charger intake
parts.
>sweet spot (ie 400cfm) and this increase density is what
gives you the
>increased mass flow that is matched with more gasoline and
gives the
>proportionate power increase.
Therefore a fan infront of
a turbo will give you denser air that finally is
able to produce more power.
With a 2 psi eRAM you'd not see 2 psi more in
the intake manifold then but
the denser air plays its rule.
>Doesn't increase spool up as the air
it is spooling is only becoming more
>dense. The alternator draw is known
to be a max of 750 watts or 50-55 amps
>or so. This is 1 hp, or call
it 2 hp with all the inefficiencies of the
>electrical power
production.
Yes, I fully agree with this :)
>4-500 cfm,
approx. This is hard to answer due to the other
major
factors
>involved. If we relieve .5psi of vacuum in the
intake system and produce
>.5psi of pressure, the net gain is 1psi.
You have to look at the problem
>from a slightly broader
perspective.
My perspective is that the eRAM may become a restriction in
the high boost
area. Calculated with 1.05 bars our cars air flow is around
544cfm@5600 and
this is without any fuel or turbo upgrade. Due to the stock
turbos the
pressure is about 0.7 bars at 7000 what results in a flow of
564cfm@7000. On
the 2 litre MR2 this was not a problem due to the flow of
about 400cfm@6000
(at 16psi).
Hmmm, the Super eRAM may then be the
answer for our bigger displacement and
high boost applications.
I
think that we have to understand that the power does not come from
any
additional boost but the higher air density the e-charger produces. And
if
the air in the intake finaly is denser too than a real gain can be
achieved.
My concerns are that the mroe dense air is not enough with the 9B
turbos
(stock) and our intercoolers efficiency. We already learned that a
cooler
ambient with denser air gives us noticeable more power. But then also
the
intercoolers do work better and this results in intake temperatures as
well.
Testing on our TT cars might be difficult as we do have much less
space in
the compartment than the non turbo cars have :(
Thanks for
the input
Roger
93'3000GT TT
PS: If we just would have any space to
mount the thing also in our cars :)
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web page is http://www.bobforrest.com/Team3S.htm
------------------------------
Date:
Sat, 31 Jul 1999 23:23:20 +0200
From: "R.G." <robby@freesurf.ch>
Subject: Re:
Team3S: Dyno/eRAM..., eRacing responds...
>Mark makes a good
point... When we did my dyno run when testing the eRAM,
>Terry (the
dyno guru at Frey Racing) was most emphatic about IMMEDIATELY
>banging the
clutch in as soon as we reached 5500 and doing the
coast-down
in
>neutral...
Was the clutch pressed or did you
switch to neutral and released the
clutch
??
Later,
Roger
93'3000GT TT
For
subscribe/unsubscribe info, our web page is http://www.bobforrest.com/Team3S.htm
------------------------------
Date:
Sat, 31 Jul 1999 23:25:56 +0200
From: "R.G." <robby@freesurf.ch>
Subject: Re:
Team3S: Vacuume hose
4 and 6 mm and a bigger (dunno the size) one for
clutch/brake.
Lenght ... no idea :)
Roger
93'300TGT
TT
>Hi guys could use some info. I am going to change all the
vacume lines on
>my 93 Stealth TT. Was wondering if anyone knows the
different sizes of
hose
>needed and the approx. lengths of each to do
the job.
For subscribe/unsubscribe info, our web page is http://www.bobforrest.com/Team3S.htm
------------------------------
Date:
Sat, 31 Jul 1999 23:34:32 +0200
From: "R.G." <robby@freesurf.ch>
Subject: Re:
Team3S: Compressor Efficiency Theory, HP 9B vs 13G
And I tried for days
how to explain the 3D compressor efficiency map in
english. Very well done
Jack ! No one can explain this better and I totally
agree with you
;-)
Thanks again,
Roger
93'3000GT TT
>RE: 9B vs
13G compressor heating air/horsepower
differences:
<snip>
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------------------------------
Date:
Sun, 01 Aug 1999 13:14:07 +0200
From: Matthews <matthews@wiesbaden.netsurf.de>
Subject:
Re: Team3S: Dyno/eRAM..., dyno stuff
"R.G." wrote:
>
> This
makes me thinking. As far as I remember, the dyno was set to the "loss
>
measuring mode" (or something like that) and the operator drove the car
in
> 4th gear up to about 6k and the left off the gas. The computer then
drawed
> the curve. To be honest, I can't remember if he pressed the
clutch then,
> switched to neutral or left it in fourth. If i recall
correctly it was the
> later.
I think he pressed in the clutch and
took it out of gear. Maybe Mike
will remember for sure. Or you
could call the guy...
- --
Jim Matthews - Wiesbaden, Germany
matthews@wiesbaden.netsurf.de
(64 Kbps ISDN)
http://rover.wiesbaden.netsurf.de/~matthews
***
3000GT-Stealth International (3Si) Member #0030 ***
http://rover.wiesbaden.netsurf.de/~matthews/stealth.html
Jet
Black '94 Dodge Stealth R/T Twin-Turbo AWD AWS 6-spd
Adjustable Active
Suspension, Adjustable Exhaust System
K&N FIPK, A'PEXi Super AVC-R (1.0
bar @ 72% BADC)
A'PEXi Turbo Timer (30 sec), Blitz Blow-Off
Valve
Magnecore spark plug wires, Redline ShockProof fluids
Metal Matrix
brake pads, custom braided brake lines
Michelin Pilot XGT-Z4 245/45ZR17, Top
Speed: 168mph
G-Tech Pro: 0-60 4.79 sec, 1/4 13.16 sec @ 113.9 mph
1 Feb
99 Dyno Session: 406 SAE HP, 354 lb-ft torque
For
subscribe/unsubscribe info, our web page is http://www.bobforrest.com/Team3S.htm
------------------------------
Date:
Sun, 01 Aug 1999 14:09:53 -0700
From: Errin Humphrey <errin@u.washington.edu>
Subject:
Re: Team3S: Exhaust Upgrade = Power? (pt.1)
Roger and others,
I
really wanted to avoid getting into this argument (which is why I
posted it
only on Starnet), as I feel that there is still severe lack
of widely
gathered data in this matter. The only dyno experiences
we have on hand
are either from Digit Power and from UPRD, a
brand new dyno shop and the
first awd dyno shop in the states
(which immediately makes me skeptical of
its accuracy). Also, I
don't want to spend too much time in this
argument, as there is still
plenty of room for strict opinion in this
matter. It is simply my
opinion that a freer-flowing exhaust system
leads to power increases
for a VR4, and I feel that no one has yet provided
convincing and
conclusive dyno data which shows otherwise. I will try
to be brief.
This is my response to Roger's response to Dave
Allison's
response to my original post (actually a response to Erik
Gross).
Dave Allison wrote (all preceded by >>):
>
>Hmmmm... I seem to recall the old HKS vehicle chart for the 91-93
3000GT
> >VR-4 going something like this:
> >
> >1991
to 93 Mitsubishi 3000GT VR-4/Dodge Stealth R/T Turbo
> >
>
>Stock (300 hp @ 9 psi)
> >
> >Stage 1 (323 hp @ 9.5
psi)
> >Turbo Exhaust System
> >
> >Stage 2 (337 hp @
10 psi)
> >Super Power Flow Air Filter
Roger Gerl responded (all
preceded by >):
> Haha, this is the known HKS joke. Why do they
tell that adding an exhaust
> increases the boost ????? Also assuming
this, 1 psi gives you 37hp.
> Therefore running 15 psi of boost will
result in 185hp -> 485hp ... yes,
> sure and I'm the King of
Mars!
Roger, you misunderstand. There is no reason to claim
rulership
over planets in order to demonstrate how little you believe in
HKS's
claims. :-) What you misunderstand is that the horsepower
gains
they claim arise from the exhaust system and air filter upgrades.
The
slight increases in boost pressure are actually side effects from
adding
these mods. I noticed I was getting about 1-1.5 psi more
boost
(measured on a boost gauge) aftter adding the K&N filter and
exhaust
w/o a boost controller. This slight increase in boost pressure
is common
and not difficult to understand, yet it does not account for much
of the
power increases.
> >the dyno to the tune of 226.9 wheel
hp. Using the 42% loss equation we now
> >see 390 flywheel
hp!
>
> Wheel hp measured and the loss look very odd !
And
that is because he has been working backwards from poor dyno
numbers measured
at the same shop which where he measured poor
dyno numbers. UPRD dynos
lousy numbers for a Subaru, but he then
says that it must be making
such-and-such flywheel hp because the
Subaru brochure says so, and thus there
must be 42% drivetrain loss,
which is simply outlandish. Dave seemed to
miss my point in the last
post that these dyno numbers for his car and this
car are plain lousy and
cannot be taken seriously without seriously calling
into question whether
or not air flow (and cooling) demands are being
sufficiently addressed.
If a quack doctor tells a bunch of people that they
have cancer, they
shouldn't be finding comfort in their common plight.
Rather they should
question the validity of that doctor's
opinion.
> So how do you explain that three cars had the very same
dyno results with
> two cars had aftermarket exhausts and one was stock
besides a K&N and boost
> controller (regapped plugs) ? And also note
that the car with the best power
> WAS THE ONE WITH STOCK EXHAUST :) Mine
had the highest torque
> curve due to the 13Gs
As Barry King
fluently pointed out, you simply cannot make universal
inferences (re:
exhaust gains/losses) based on your dyno ~comparison~
among these cars.
The only test which would be valid would have been
dynoing one car with stock
exhaust, and then on the same day removing
the exhaust system and gutting the
precats and re-dynoing that car.
Period. Yet in addition, the airflow
issues must still be addressed, and
in my opinion your reasoning towards the
airflow issue is flawed (see pt.2).
The airflow issues even becomes more
important for an exhaust-modified
car, if said modification indeed brings
about an increase in power and
a slight increase in boost
pressure.
> Therefore one would assume that
> reducing the
backpressure increases the efficiency. One positive side effect
> is that
the discharge temperature is also be lower. Unfortunately our
>
measurements did not show any difference :(
The only measurements which
would have actually shown this would
have been measurements of the ~same~
car, with and without the
stock exhaust and precats.
> So what does
the cat-back exhaust do performance wise ? It's weight and a
> better
spool-up of the turbos between shifting. Therefore a real gain in the
>
1/4 mile can be found, but as said, it doesn't d give you more horses
!
TD04-9B spool-up is hardly an issue during 1/4 mile runs, except
maybe
to some degree in your launch (in which case the effect on
trapspeeds
is still negligible). We launch our cars at high rpms and we
shift them
with partial or full throttle at redline. The turbos are
well-spooled the
whole way. Spool-up is only an issue for low-speed
daily driving or
off-the-cuff highway roll-ons from lower rpms. Try
flooring your car
out of 5000rpms, and see if you think that spool-up is an
issue there.
> I spoke with several dyno-owners here in Switzerland
and they told me that
> they found a loss of 20-30% on AWD cars and 12-18%
on 2WD cars.
This would only show that on average AWD cars have about
60%
more drivetrain losses than their RWD counterparts. This
argument
came up before, regarding their method for estimating flywheel hp,
but
it is simply my opinion that the only way to achieve an accurate
figure
is to dyno hp at the wheels and then remove the engine to
measure
bhp at the flywheel. I feel the same way about the
G-Tech. It's fine
for making comparisons for the same car (e.g. before
and after some
modification), but it is not well-suite for comparisons across
different cars.
> I'll be on the dyno pretty soon to tune in the water
injection. I currently
> have the full stock exhaust back on the car and
we'll first find the
> detonation point before tuning in the WI. This will
gives us a good sheet to
> compare then.
I am eagerly awaiting
these results. :)
This concludes my response to the Dave
Allison/Roger Gerl post.
My next post (pt. 2) addresses Roger's reponse to my
own post.
Stay tuned,
- --Errin Humphrey
Seattle, WA
UW
undergrad
94 VR4
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------------------------------
Date:
Sun, 01 Aug 1999 14:10:24 -0700
From: Errin Humphrey <errin@u.washington.edu>
Subject:
Re: Team3S: Exhaust Upgrade = Power? (pt.2)
Roger and others,
This
is my response to Roger's response to my original post (which
had been quoted
by Dave Allison in his reponse to me).
Errin Humphrey wrote (all
preceded by >>):
>> The general rule of thumb is that for
each mph
>> you gain in the 1/4 corresponds to an increase of
approximately 10rwhp.
Roger Gerl responded (all preceded by
>):
>This is the typical misleading from the earlier years. This
because every-
>thing is based on NA, nitrous or SC cars but not on turbo
charged cars.
>The big problems on turbo cars is the lag on the system and
we cannot
>eliminate it. Here a better flowing exhaust helps (as well a
BOV may be
>able to do)
Unfortunately for your case, you are wrong
here. If this were true,
then I wouldn't have seen so many Supra owners
dyno their cars and
then run their cars at the track leading to increases in
trapspeeds which
almost ALWAYS corresponded to the above approximation
(within
acceptable variance). I was on the Supra list for about a year
and saw
this confirmed time and time again, and I also learned a lot about
the
need for ~proper~ dynoing procedures as well the importance of
getting
a second "opinion" (i.e. don't just keep going to the same dyno).
And I've
talked to a few RX7 and 300ZX guys who have noticed the
same thing.
Simply put: I have heard of plenty of turbo cars who have
seen their
trapspeeds increase along with dyno'd horsepower in
accordance with the above
approximation. Furthermore, as I said earlier,
the spool-up issue is a
~non-issue~ in dragracing our cars. It certainly
isn't important enough
to explain throw out the above formula. [Since
you have referred to
both lag and spool-up, which are somewhat different,
I'm just ignoring the
difference and discussing them as the same].
I still have yet to hear an
adequate response which explains why our
trapspeeds would increase with only
exhaust mods. It is unfortunate
that you have not made any runs at the
track, and this seems to be
the dividing line between us. Allow me to
approach the issue from a
different direction, in light of your recent
attempy to explain away the
increase in trapspeeds which we have
measured.
Mike Mahaffey posted to Starnet:
>However, when I
installed my Borla exhuast, I went from consistent
>13.4's at 101mph to
consistant 13.1's at 103mph. Statistically, that
>would show a gain
over 20hp on my car..
So Mike gains 2mph in the 1/4 mile after only
adding a Borla. (I got
about 3-4mph after doing full
exhaust/dp/precats). Now, your opinion
that the above dragger's
approximation is inapplicable to turbocharged
cars says the following:
Mike's gain of ~2mph does NOT really correspond
to a gain of 20hp but rather
some number far less, say 2hp (since you
are always claiming "NO GAINS" based
on your dyno figures). Now
what is your explanation for this
idea? You say that it is because turbo
cars have "lag on the system and
we cannot eliminate it." Huh? That
goes entirely against your
position. To say that lag is a problematic char-
acteristic for
turbocharged cars is to say that a gain of 2mph in the 1/4-mile
should
correspond to MORE horsepower gained, relative to "NA, nitrous
or SC
cars." That simply makes no sense at all. There would have to
be
some ~huge~ advantageous factor which he have not yet discovered
which would
make turbocharged cars able to gain increases in trapspeeds
much easier than
cars which use other methods of forced induction. That
is a claim which
requires a LOT of explanation.
So your explanation that "lag" is the
reason why exhaust mods add no
hp, or the auxiliary assumption that lag is a
problem on the dyno but less
problematic in the real world, does not help
your case. It hurts it. It
would tell us that for turbocharged
cars the equation should actually say
something like, 1mph = ~25hp, in order
to take lag into account (whether
in general, or only on the dyno). If
there is truly a handicap which has
been hurting turbocharged cars on the
dyno, it is most likely what I have
been trying to tell you all along:
insufficient airflow/air-cooling, and that
just tells the following:
*That in the ~real-world~ our cars are making
much more power, and exhaust
mods are able to bring about net gains.
This could easily explain the
dichotomy between our experiences.
>I do not like if someone just says
"exhaust". This because we have :
>- pre-cats
>- downpipe
>-
main cat
>- cat-back (piping, muffler)
Fine. We'll just let
"exhaust" mean the whole deal, all of the above. I have
no problem with that,
especially since you and Mike both had the whole
works for your dyno
tests. If others (such as Mike M.) have seen increases
in trapspeeds
with only catback, etc., then it only works to my favor.
:)
>Therefore we must be careful on what we are talking about. And
the
>dyno sheets show that changing the cat-back, removing the main
cat
>and replacing the dp didn't helped anything. As measured on the
same
>dyno, same day with same environment we can say that this is fact
!
On different cars, and that is a fact! :) Roger, you made dyno
runs with
your car and you ~didn't even have proper tires on the car~!
You had
snow tires which were melting on the rollers. There are a tons
of other
factors which you did not address in your comparisons. For
instance,
engine compression tests, miles on the cars, age of spark plugs,
Mike
was on stock BPV, most recent tuneup, Jim's is '94 wheares Mike's
is
'95 (w/ OBDII), and the list goes on. Again, you cannot take a
test
like this and make ~universal~ inferences about ALL 3000GT's. It
is
going to take a ~lot~ more than this to convince me of your claims,
as
well as an explanation for my own (and other's) experiences at the
track.
>> The problem with the dyno runs is their very
nature. Automobiles
>> were not designed to make high power while
sitting still. They were
>> designed to make high power at speeds
which provide massive airflow
>> which is nearly impossible to
reproduce in a dyno shop.
>And this is why the hood is kept open
during the dyno and there is no
>air-resistance (dunno the right word).
And as the massive air resitance is
>not calcuated in any power formula it
is more accurate on the dyno.
Roger, with all due respect, you are so
wrong here that I am almost at
a loss for words. What you are
essentially saying is that since there is
no air-resistance the car will not
have to work as hard, and thus there is
no need to worry about your car's
airflow needs. If the dyno technician
fed you this B.S. I would
personally never show my face there again.
From simple physics, the fact
of the matter is that an automobile (esp.
a turbocharged one) requires a
~load~ on the drivetrain in order to
produce significant horsepower.
Your car will make almost no hp if
your wheels are lifted off of the ground,
just as it takes very little hp
to maintain constant highway speeds.
And the fact of the matter is that
aerodynamic resistance is functionally
equivalent to frictional resistance
from the road, as far as your vehicle's
need to produce torque at the
wheels is concerned. Now, just because
the dyno rollers don't (as far
as I know) attempt to emulate the additional
aerodynamic resistance
does NOT mean that its airflow requirements are
somehow reduced
as a result of the decreased load. In fact, if the
rollers don't provide
enough resistance, your dyno figures will not be
representative of real-
world horsepower (which would be higher). But
the fact of the matter
remains that reduced load on the car has almost
~nothing~ to do with
whether or not airflow requirements (esp. to the I/C's)
are being met.
Think of it this way: What would you rather
do? Run 10 miles up a
hill in 15°C weather with plenty of cool water to
drink OR run 10 miles
on a treadmill in a 35°C room with only an occasional
mist of warm
water sprayed on your face? Maybe neither sound very
appealing :)
but you can see that in the second case less is being asked of
you, yet
conditions are much less favorable. You ~cannot~ assume that
the two
issues will always necessarily cancel each other out.
Also,
what you said about air resistance not being calculated in power
formulas is
simply not true. You are probably basing this statement on
people
having said that the G-Tech doesn't take aerodynamics into
account and that
is why figures often differ from real track data, yet this
is not true
either. The truth is that all power formulas and the G-Tech do
take
aerodynamic resistance into account, BUT they only make certain
assumptions
about it. They include factors which would apply to an
average car
under average ambient conditions. If they didn't, the basic
mph to hp
estimate formula would give you hp figures probably less than
half of what
they actually are. The way in which these formulas take air
resistance
into account isn't beyond comprehension, but it does involve
some nasty
integrations.
>The only drawback is the less cooling on the ICs and
therefore the less
>power due to the less dense. But an earlier test
showed that on my car
>this made only a difference of about 2.5 hp with
the fan switched off. Also
>our ambient temperature on February was 10°C
in the dyno room and
>therefore air was dense enough.
Turning the
fan on and off told you ~nothing~ about whether or not
there was sufficient
airflow for your intercoolers to be efficiently working
at all. Of
course, at certain highway speeds there will be excess airflow
for your
intercoolers to work sufficiently, but you cannot simply assume
that the fan
provided anywhere near this level, and all Supra dyno-ers
have reported that
a fan by itself is never sufficient.
>> I have several times
suggested that this must be the prime reason why
>> Roger and the
others were noticing tons of knock (from detonation)
>> when dynoing
their cars. This is greatly exacerbated when you make [snip]
>No, this
is not really true although your theory is very right. I had my car
>on
the dyno 5 times with the oil temperature measured. It never went
higher
>than 112°C (usually stayed below 100°C) compared to a 300ZX TT
with
>temps of up to 160°C and the Supra with 143°C. Also the water
temperature
>never ever moved a little and therefore was not a problem. I
thought that on
>one Stealth it was moving just a very little but
negligible.
That's fine in regards to whether or not the engine was
overheating, but
it says nothing about whether there was sufficient airflow
to provide an
adequte amount of fresh cool air for the intake as well as
enough airflow
to make the intercoolers efficient. You need intake air
temp measurements
to address this issue, not oil and water temps, and they
should be compared
to temps of when the car is on the road, not to the temps
of other cars that
are in the shop. Also, it seems presumptuous to put
so much faith in the
accuracy of measurements made by just one instrument,
and then make
such universal statements as you have.
Another thing
about the dangers of overheating on the dyno (and whether
there is truly
adequate airflow). After your engine blew while on the dyno,
you posted
the following under the heading "Dyno Session 2 ... problems !":
>I
currently don't know what the problem is and I'm also not sure about
the
>theory. Anybody has another idea or already runned into the same
problems?
>BTW, oil temp was max. 208.4°F, water temp ok and oil pressure
good
>(was somewhat high at the beginning of this week)
Just
something to think about.... Even though the damage might have
started
on the highway, your engine was running until you put it on the
dyno.
>> And keep in mind that when sufficient knock is present,
the computer will
>> drastically retard the timing thus leading to huge
decreases in power (esp.
>> for a free-flowing exhaust car which
is demanding more air).
>Well, in a turbo system the turbos themselfes
are a restriction as this is
>how the system works. As described before
(pressure difference) a free
>flow exhaust helps to improve efficiency and
the pressure before the
>turbos is what counts.
Of course, but you
haven't addressed the intercooler issue. On many
cars which add
aftermarket turbos/SC I often hear different psi limits
past which an
intercooler is a necessity to avoid engine damage. It is
seldom above
10psi, and yet there you guys were at Digit Power with
your cars on the dyno
running 0.9-1.0+ bar with the possibility that there
was ~not~ sufficient
airflow to ~both~ of your intercoolers (the fan may
not have been large
enough, and you did not ice them) that you may as
well have NOT had
intercoolers. That is a ~bad~ thing, and I have
continued to remind you
(and Dave, Mikael) about it for your own good.
I feel really bad when I hear
about another blown engine or lousy dyno
results (esp. like Mikael who did no
icing procedures).
>But of course more pressure then can also cause
some temperature
>and backpressure problems. You are right about the
detonation/knock
>but I had the same knock at 15+ psi also on the
road.
Have you yet confirmed that Euro-VR4's have larger stock injectors
and
fuel pump to be properly matched to the 13G's? Otherwise, you
can't
use this to discount detonation on the dyno.
>> Roger
actually blew his engine while on the dyno, but he blames it on
>> his
extended 170mph Autobahn runs . . .]
>No, my engine blew during my
ignorance after I installed the boost
>controller during my G-Tech
sessions. During the Autobahn runs the
>knock was then hearable and the
oil steam comming out of the BOV
>was very visible :( I did the
174mph with the engine already in a bad
>shape and I'm sure the other
rings then finally went south.
What about the possibility that your older
dyno runs (esp. at high boost)
started the damage, your Autobahn runs
exacerbated it, and your next
dyno runs (Session 2) were the final blow to
your engine?
>> Most dyno shops have fans, but any competent dyno
technician can tell
>> you that this is nowhere near the amount of air
that is flowing when your
>> car is moving at just 60mph. Stick
your hand out the window on the
>> freeway some time to find
out.
>And exactly here you'll learn how much power it takes to get
through this
>resistance. I think that this is definitely not a negligible
amount. Finally, less
>cooling but no air drag may give you close numbers
for street and dyno.
And as I explained earlier, this line of reasoning
is flawed. Reducing the
load on a car reduces its difficulty in
performing certain levels of accel-
eration, but it does not necessarily
reduce its demand for air (esp. for
cool air at high boost) by some sort of
1:1 ratio. In other words, you are
making a MAJOR unjustified
assumption when you say that no air drag
will completely cancel out the lack
of cooling and sufficient airflow.
>> When I was on the Supra list
I learned that most of them get lousy dyno
>> numbers unless they take
every possible measure to attempt to simulate
>> the airflow of higher
speeds. This includes icing the intercoolers, icing the
>> engine,
icing all the piping, and making sure that you have the biggest
>> damn
fan on the planet blowing at the front of your car.
>You know that the
Supras have tiny IC stuff and are getting pretty hot very
>quick. Upon our
experience this is not a real problem on our cars, at least
>not in the
15psi area !
Unless, of course, the sensitivity of your measuring
equipment differs at
all from your car's stock knock sensor.
Furthermore, just because you
found that 1.05 bar is the right where
detonation starts on the dyno, that
does not mean that it was good for your
car to be running "on the edge"
of detonation, and it says little about what
happens in the real world.
>If you say that this statement is wrong,
then please explain why three cars
>with different exhaust haven't seen a
difference in power and the one with
>the stock exhaust showed the highest
figure. Please note that the three cars
>have been tested at the same dyno
on the same morning with the same
>temperatures, etc.
They were
different cars. Way too many variables still unaccounted for.
And in
addition, your car should have been immediately factored out as
a result of
it's being a Euro-Vr4 with larger turbos, yet still no confirmation
as to
whether it received upgraded fuel components. Also, there was
that
little issue about the snow tires.
>> If that were the case then we
would never see increases in trapspeeds
>> after upgrading exhaust,
regardless of the fact that the "1mph = 10hp"
>> dragger's rule is just
an estimate.
>As said this belongs not to turbo charged engines. It
would with eliminated
>lag ! Also reduced weight can be counted in
although this is maybe not that
>much.
I would really like to hear
an explanation as to how "lag" is what causes
1mph to instead = 0hp, whereas
with other cars (na, nos, sc) which don't
have lag it takes them 10hp to
achieve this. The reduced weight is certainly
not enough to account for
the differences.
>> And furthermore I am too pessimistic about the
airflow problems with
>> their dyno runs. I am more than willing
to accept that one day they might
>> get the airflow issue straightened
out and "prove" that a freer-flowing
>> exhaust doesn't provide power
gains (which in itself makes no sense for
>> a turbocharged
car)
>I always thought that I'm the most sceptical one on the small
blue ball,
>hehe. But as I'm skeptical and only believe in what I say and
what I get I'd
>ask you for the technical background with the formulas
behind your last
>sentence.
I don't have to bother because I can
just quote from your own posts. :)
You wrote:
>As the pressure
difference between in front the turbo and afterwards
>causes the turbine
to spool, a larger difference makes them more efficient.
>Therefore one
would assume that reducing the backpressure increases the
>efficiency. One
positive side effect is that the discharge temperature is also
be lower.
Unfortunately our measurements did not show any difference :(
So in
principle you realize why ff-exhaust should make a difference in
power, but
your dyno measurements did not confirm this. The whole time
I have been
trying to remind you of airflow, cooling, detonation issues
as well as the
danger of making too many generalizations from only a
couple cars with too
many variables present.
>As there was no real airflow issue on our
dyno session (it was
>once an issue on a dyno with 33°C ambient temp.) I'm
positive that the
>air-resistance will be a higher issue on the
street.
Yes, but air resistance is just another resistive force (like
frictional force
with the road due to your car's weight) which the torque at
your wheels
must overcome. Eliminating this extra load does not mean
that your car's
airflow needs will be magically reduced by the same
amount.
>With the datalogger I can now log the detonation on the
street and on the
>dyno. Therefore we'll be able to compare the data then,
including intake
>temperature, timing, etc. Also I'll record boost and
intake temperature with
>my own tool as well and try to bring the stuff
together later.
Sounds great! I'm sure this will shed MUCH light on
the issue. Even
with the whole exhaust issue aside (and if further
tests show I am wrong),
I just really want to encourage you and other dynoers
to really go the
extra mile (w/ icing techniques, etc.) when you dyno your
cars. Putting
your car on the dyno is, in my opinion, on of the
harshest things you can
put your car through. I will truly feel bad if
you or anyone else blows
an engine again.
It has been a pleasure
discussing this with you. :)
Highest regards,
- --Errin
Humphrey
Seattle, WA
UW undergrad
94 VR4
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subscribe/unsubscribe info, our web page is http://www.bobforrest.com/Team3S.htm
------------------------------
Date:
Sun, 1 Aug 1999 23:14:39 -0500
From: "Matt Jannusch" <mattj@fallon.com>
Subject: RE: Team3S:
Exhaust Upgrade = Power? (pt.2)
> >As said this belongs not to
turbo charged engines. It would with
> >eliminated lag ! Also reduced
weight can be counted in although
> > this is maybe not that
much.
> I would really like to hear an explanation as to how "lag" is
what causes
> 1mph to instead = 0hp, whereas with other cars (na, nos, sc)
which don't
> have lag it takes them 10hp to achieve this. The
reduced weight
> is certainly not enough to account for the
differences.
I'd also like to know how this works. It would seem to
me that if we are
looking at a figure that is generally accepted for a NA car
(.1 second = 10
hp), and we have turbo lag and a higher drivetrain loss, then
the figure
should be even higher for us as we are applying the additional
thrust to the
car later down the dragstrip and have to make up that .1 second
in less
distance. So in my line of thinking for a turbo car with
significant lag
(which I don't feel our cars have in the first place - not
significant lag
anyway) and higher drivetrain losses - .1 second would equal
perhaps 12-14
hp.
(I probably should've quoted from the previous
e-mails for the next two
sections, but I already deleted the relevent
sections)
I also disagree with drawing any generalizations about
horsepower increases
caused by certain modifications when the testing isn't
even done on the same
car. No two cars are going to dyno identically,
even under the same
conditions.
I also agree that running your car on
a dyno without proper airflow
*through* the intercoolers, (not just a fan
pointing in their general
direction, but actually ducting air through them so
the air doesn't just go
around the intercooler edges) is likely to cause
serious damage to your
motor. The engine system on these cars is
engineered as a unit, designed to
have the intercoolers cooling the intake
charge a vast amount under the
temperature the turbos are spewing out.
To make the intercoolers not do
their job by not flowing large amounts of air
through them is going to cause
a large amount of knock initially, and
detonation if the charge temps don't
drop. This is a very bad thing,
not only because the dyno results will be
inconclusive (since the car is not
being run under normal conditions), but
because engine damage is a high
probability.
I wouldn't run my car on a dyno without proper
intercooling... Ouch! If
you don't think the intercoolers matter,
you might as well take them off and
save the weight.
- -Matt
'95
3000GT Spyder VR4
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------------------------------
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