Pulley on down......
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Posts like a Ricer Type-R
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He'* just finding the limits, guys. And a 3.3 tomorrow doesn't mean a 3.3 at Woodburn in July. Paul is very well aware of that fact. 
He'* kinda been playing this game for about 4 years.
He'* kinda been playing this game for about 4 years.
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Junior Member
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Oh Bill, don't make me sound so devious. 
Yes it did adjust to the 3.4 after about an hour of driving.
Tomorrow I will try and do the same for an hour with the 3.3.
At the next opportunity, I will try the 3.2
.......and then.......
the 3.1
.......and then.......
the 3.0
......and then........
the 2.9
Yes it did adjust to the 3.4 after about an hour of driving.
Tomorrow I will try and do the same for an hour with the 3.3.
At the next opportunity, I will try the 3.2
.......and then.......
the 3.1
.......and then.......
the 3.0
......and then........
the 2.9
Senior Member
True Car Nut
Joined: Dec 2002
Posts: 5,459
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From: Sauk Centre, MN
You have me salivating for some run time in my 99. I've put 40 miles on it since I got it roadable.
I have the 3.4" on the SC now, but the S1X should give me a chance @ the 3.3". Gotta ditch the P-log and PEM for some of these:
http://cgi.ebay.com/ebaymotors/1997-...spagenameZWDVW
Then, dyno, then GEN V time!!! And back to the 3.4 probably.
I have the 3.4" on the SC now, but the S1X should give me a chance @ the 3.3". Gotta ditch the P-log and PEM for some of these:
http://cgi.ebay.com/ebaymotors/1997-...spagenameZWDVW
Then, dyno, then GEN V time!!!
And back to the 3.4 probably.
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Posts like a Ricer Type-R
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The two most succesfull ported Gen3'* (one M62 and one M90) that I know of
were able to drop 0.2" on pulley size without KR, and also a Gen2 M62 before
that. From all the reading I've done, this is NOT attributed to the outlet as much
as it is the inlet, which most off-the-shelf porting sources don't do.
I'm quite curious to see if your GenV responds the same as the SC'* Boosty and
I have done, as well as seeing if Harofreak'* and Shadd'* SC'* do the same as
well.
So far, the inlet porting seems to have reduced boost charge temps enough to allow
us to drop 0.2" in pulley diameter without an increase in KR. This is why boosty
was able to run a 3.2" pulley on PEM'* before he did the rockers. And why I was
able to run a 2.2", then a 2.0" on a Gen3 setup that would have normally run with a
2.5".
I may use my 'old' ported Gen3 on the 95 to prove that point further, with no changes
to the exhaust at all. But that'll be after the next ported Gen3 goes on the Zilla for testing.
Every thermal analysis model I've seen or performed myself has shown the inlet to
be the hot spot. None of the models took into account the surface roughness, but
all of them showed the inlet being the hottest if it were SMOOTH. The roughness
only hurts more. Smoothing this out is a big benefit.
This analysis was done by a group of college engineering students back in 2002 IIRC:
You can see that the inlet is the hottest surface. Black being coolest, white
being hottest. When I ran the same model several years later with a much better
CAD package, I got this:
Paul, I'll be very curious to see if the GenV proves to follow along the same path
after smoothing, porting, and polishing. It wasn't quite as rough as the M62'* and
M90'* I've done, but it was similar. I'd expect you to run a smaller pulley after that
work than one would normally expect.
were able to drop 0.2" on pulley size without KR, and also a Gen2 M62 before
that. From all the reading I've done, this is NOT attributed to the outlet as much
as it is the inlet, which most off-the-shelf porting sources don't do.
I'm quite curious to see if your GenV responds the same as the SC'* Boosty and
I have done, as well as seeing if Harofreak'* and Shadd'* SC'* do the same as
well.
So far, the inlet porting seems to have reduced boost charge temps enough to allow
us to drop 0.2" in pulley diameter without an increase in KR. This is why boosty
was able to run a 3.2" pulley on PEM'* before he did the rockers. And why I was
able to run a 2.2", then a 2.0" on a Gen3 setup that would have normally run with a
2.5".
I may use my 'old' ported Gen3 on the 95 to prove that point further, with no changes
to the exhaust at all. But that'll be after the next ported Gen3 goes on the Zilla for testing.
Every thermal analysis model I've seen or performed myself has shown the inlet to
be the hot spot. None of the models took into account the surface roughness, but
all of them showed the inlet being the hottest if it were SMOOTH. The roughness
only hurts more. Smoothing this out is a big benefit.
This analysis was done by a group of college engineering students back in 2002 IIRC:
You can see that the inlet is the hottest surface. Black being coolest, white
being hottest. When I ran the same model several years later with a much better
CAD package, I got this:
Originally Posted by willwren
What'* the hottest surface? The INLET. Not the outlet. Why? Restriction/friction
of airflow. To be honest, this is a very simple model. It doesn't have the cooling
ports, and some of the conditions may be based on theory, rather than reality. So
we take this data as a starting point, and try to refine the model (this analysis was
done by a group of college engineering students at least 3 or 4 years ago.
Fast forward to the current state of the Zilla:
See the little temperature strips? There are 9 of them on the SC, Nosedrive, TB,
and LIM. Why? I wanted to know not only WHAT temperatures were typical in
different driving conditions, but also HOW it heats up. What'* hot first? Where
does the heat start, and how does the SC react during heatsoak? Does the
coolant actually HELP?
So then I made a model.
That was a long time ago, and for another purpose as well, but a good 3D model is
the starting point for a good thermal analysis job.
So I took everything I learned from the original thermal analysis (top image in this topic),
and everything I learned from REAL data from my own car (coolant temps, stuck-on
thermal temp strips, and IR heat analysis) in multiple conditions. Different ambient air
temps, wet weather, dry weather, street conditions, long trips, and track.
Now let'* apply all THAT to the 3D model WITHOUT coolant flow (temps are typical on
a warmed up engine after about 15 minutes of driving in ambient 60°F air, 200° LIM):
The dark blue is constrained to 150°F (338Kelvin) to represent engine bay ambient
temps, and the bottom surface is constrained to typical LIM temps. As you can see,
the BOTTOM of the inlet is the hottest surface. This is what pre-heats your incoming
air for you. Nice, huh?
Now let'* induce some coolant flow and kick up the incoming air temp a bit to REALLY
see what'* going on (85° ambient air, 180° coolant temp in the SC coolant ports, 250°F
LIM temp):
See the positive result in the inlet despite the increased IAT and LIM temps?
Coolant flow controls it. See the outlet edges got hotter? That'* why we smooth them.
They're 'factory sharp' but not 'factory rough' in this model.
Now to be honest, there are other factors at work here, but I think I've captured the
critical data very well in these models. On a track, with sufficient cooling, you'll be OK.
SC temps don't spike at the track until AFTER the run. But if you drive your car daily,
you need the coolant. And you can STILL cool down between runs at the track. You've
lost nothing.
Ideal solution? A seperately cooled interface plate between the SC and LIM, that routes
coolant (not engine coolant) through the plate beneath the SC, and through the SC to the
TB. Something like this:
Further incoming air temp improvements are the direct result of polishing your SC inlet.
As a point of comparison:
My Gen3 M62 inlet and TB run 15° cooler than Matt'* Gen3 M90, despite the fact that
I was moving far more air with a 2.0" pulley than his stock 3.8" pulley. This is a direct
result of polishing the rough inlet surface left over from the casting process.
This was after an extended high-throttle side-by-side run in 106°F ambient conditions.
I hope I've answered the question from this topic, at least with regards to the L67'* out
there. The data is going to come out differently for L27'* and L36'*, as the inlets won't
be as hot to begin with. But it'* something to chew on.
of airflow. To be honest, this is a very simple model. It doesn't have the cooling
ports, and some of the conditions may be based on theory, rather than reality. So
we take this data as a starting point, and try to refine the model (this analysis was
done by a group of college engineering students at least 3 or 4 years ago.
Fast forward to the current state of the Zilla:
See the little temperature strips? There are 9 of them on the SC, Nosedrive, TB,
and LIM. Why? I wanted to know not only WHAT temperatures were typical in
different driving conditions, but also HOW it heats up. What'* hot first? Where
does the heat start, and how does the SC react during heatsoak? Does the
coolant actually HELP?
So then I made a model.
That was a long time ago, and for another purpose as well, but a good 3D model is
the starting point for a good thermal analysis job.
So I took everything I learned from the original thermal analysis (top image in this topic),
and everything I learned from REAL data from my own car (coolant temps, stuck-on
thermal temp strips, and IR heat analysis) in multiple conditions. Different ambient air
temps, wet weather, dry weather, street conditions, long trips, and track.
Now let'* apply all THAT to the 3D model WITHOUT coolant flow (temps are typical on
a warmed up engine after about 15 minutes of driving in ambient 60°F air, 200° LIM):
The dark blue is constrained to 150°F (338Kelvin) to represent engine bay ambient
temps, and the bottom surface is constrained to typical LIM temps. As you can see,
the BOTTOM of the inlet is the hottest surface. This is what pre-heats your incoming
air for you. Nice, huh?
Now let'* induce some coolant flow and kick up the incoming air temp a bit to REALLY
see what'* going on (85° ambient air, 180° coolant temp in the SC coolant ports, 250°F
LIM temp):
See the positive result in the inlet despite the increased IAT and LIM temps?
Coolant flow controls it. See the outlet edges got hotter? That'* why we smooth them.
They're 'factory sharp' but not 'factory rough' in this model.
Now to be honest, there are other factors at work here, but I think I've captured the
critical data very well in these models. On a track, with sufficient cooling, you'll be OK.
SC temps don't spike at the track until AFTER the run. But if you drive your car daily,
you need the coolant. And you can STILL cool down between runs at the track. You've
lost nothing.
Ideal solution? A seperately cooled interface plate between the SC and LIM, that routes
coolant (not engine coolant) through the plate beneath the SC, and through the SC to the
TB. Something like this:
Further incoming air temp improvements are the direct result of polishing your SC inlet.
As a point of comparison:
My Gen3 M62 inlet and TB run 15° cooler than Matt'* Gen3 M90, despite the fact that
I was moving far more air with a 2.0" pulley than his stock 3.8" pulley. This is a direct
result of polishing the rough inlet surface left over from the casting process.
This was after an extended high-throttle side-by-side run in 106°F ambient conditions.
I hope I've answered the question from this topic, at least with regards to the L67'* out
there. The data is going to come out differently for L27'* and L36'*, as the inlets won't
be as hot to begin with. But it'* something to chew on.
after smoothing, porting, and polishing. It wasn't quite as rough as the M62'* and
M90'* I've done, but it was similar. I'd expect you to run a smaller pulley after that
work than one would normally expect.
Thread Starter
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Good response Bill and exactly the reason I think I can, against recommendations to run .2 pulley size larger with the Gen V, run the same size I was able to get away with before with the Gen 3.
I had been running with the 3.2" before with 0 KR.
I think I should be able to run a 3.2" now with the Gen V, thanks to the porting and polishing and I'm going to prove it.
I don't want to "have to" use the water injection until I go smaller, or bump up the timing, for extracuricular racing activities.
Remember I ran the 3.1" for a solid year back in 05 on 94 octane with no problems and still took home the prize for quickest 1/4 mi run at our Meet.
Bad news, this morning. :( The Fog has left the roads wet
If they don't dry out within the next 3 hours, we will have to be patient for another week.
I had been running with the 3.2" before with 0 KR.
I think I should be able to run a 3.2" now with the Gen V, thanks to the porting and polishing and I'm going to prove it.
I don't want to "have to" use the water injection until I go smaller, or bump up the timing,
for extracuricular racing activities. Remember I ran the 3.1" for a solid year back in 05 on 94 octane with no problems and still took home the prize for quickest 1/4 mi run at our Meet.
Bad news, this morning. :( The Fog has left the roads wet
If they don't dry out within the next 3 hours, we will have to be patient for another week.
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Aug 27, 2003 11:30 AM