Trouble acceleration from 100mph and up (Watkins Glen experience)
#1
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Trouble acceleration from 100mph and up (Watkins Glen experience)
I was at the QClub DE event earlier this week... the car ran great and had a blast. However, I've been thinking about why my car has trouble accelerating from 100 (105) and up in the back straight. Everytime I look down at the speedo after tracking out I'm at ~105. Even if I throw it in 5th, car would have trouble getting past 110 before the brake zone.
If you are familar with Watkins Glen, I'm at WOT in 4th gear from turn 2 all the way up to track out on top.
Is it because:
a) Drag - I need much more power to move/accelerate my car at that speed.
b) Gearing - 5th gear doesn't give me that great of acceleration
c) Heat - heat soak on the intercooler
d) combination of a number of things above?
I've attached my video of 2 laps at the Glen. enjoy.
Cris<ul><li><a href="http://lobster.2limited.com/av/track/Watkins%20Glen%20July%202003.wmv">http://lobster.2limited.com/av/track/Watkins%20Glen%20July%202003.wmv</a></li></ul>
If you are familar with Watkins Glen, I'm at WOT in 4th gear from turn 2 all the way up to track out on top.
Is it because:
a) Drag - I need much more power to move/accelerate my car at that speed.
b) Gearing - 5th gear doesn't give me that great of acceleration
c) Heat - heat soak on the intercooler
d) combination of a number of things above?
I've attached my video of 2 laps at the Glen. enjoy.
Cris<ul><li><a href="http://lobster.2limited.com/av/track/Watkins%20Glen%20July%202003.wmv">http://lobster.2limited.com/av/track/Watkins%20Glen%20July%202003.wmv</a></li></ul>
#2
And a big honkin' hill!
Hey Cris, it was good to see you at the Glen.
The same thing happens to me coming up the back straight, and to save my pride, I blame it all on the hill! If you check out an elevation map of the track, there's a good 90 feet difference between the bottom of the Esses and the entry to the Bus Stop.
Now, if I'm being realistic, I blame it on all these things:
a) the driver
b) the hill
c) drag, gearing, and heat-soak
When I completely nail everything, which is nice and smooth into turn 1, full-throttle at the Apex in 3rd gear, exit speed of 78mph (which I saw exactly *once* in 2 days,) upshift to 4th between turns 1 and 2, and full throttle the rest of the way (through turns 2, 3, and 4) I'm able to touch 115 into the Bus Stop -- but only if I brake late.
The car totally falls on its face on the back-straight as I top out 4th gear, but I seem to lose more time upshifting than I can make-up. I'm sure I'm leaving a little on the table in turn 1 still too.
See you next month back at the Glen??<ul><li><a href="http://dbserver.iscmotorsports.com/TheGlen/maps.cfm?MapStoryID=5636&TemplateDisplayMode=2 &TeaserMode=False&PreviewLevel=0&Estab lishmentType=T&Establishment_ID=13&">Watki ns Glen elevation map</a></li></ul>
The same thing happens to me coming up the back straight, and to save my pride, I blame it all on the hill! If you check out an elevation map of the track, there's a good 90 feet difference between the bottom of the Esses and the entry to the Bus Stop.
Now, if I'm being realistic, I blame it on all these things:
a) the driver
b) the hill
c) drag, gearing, and heat-soak
When I completely nail everything, which is nice and smooth into turn 1, full-throttle at the Apex in 3rd gear, exit speed of 78mph (which I saw exactly *once* in 2 days,) upshift to 4th between turns 1 and 2, and full throttle the rest of the way (through turns 2, 3, and 4) I'm able to touch 115 into the Bus Stop -- but only if I brake late.
The car totally falls on its face on the back-straight as I top out 4th gear, but I seem to lose more time upshifting than I can make-up. I'm sure I'm leaving a little on the table in turn 1 still too.
See you next month back at the Glen??<ul><li><a href="http://dbserver.iscmotorsports.com/TheGlen/maps.cfm?MapStoryID=5636&TemplateDisplayMode=2 &TeaserMode=False&PreviewLevel=0&Estab lishmentType=T&Establishment_ID=13&">Watki ns Glen elevation map</a></li></ul>
#3
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Re: And a big honkin' hill!
After track out at top of the hill, I would burn a second or so shifting to 5th... and there is really no time to accelerate more before the braking zone comes up. Oh well.
I'll have to keep an eye on the exit speed out of turn 1 next time.
Yes, I'll be at the Aug. event. So, I'll defintiely see you there!
Cris
I'll have to keep an eye on the exit speed out of turn 1 next time.
Yes, I'll be at the Aug. event. So, I'll defintiely see you there!
Cris
#5
Sorry guys...it's heat soak.
I data logged runs there last year and the intake temps were horrendous. I have a high flow TAP (I hate that company) stock mount intercooler so I figured I would be somewhat OK. It wasn't.
If I was tracking the car still, I would set up an intercooler mister using the headlight washer pump and a relay switch on the dash. With a little experimenting, I think you could find the right nozzle size that would allow the washer resevoir (which is rediculously huge) to last an entire 20 minute session.
Mike O.
If I was tracking the car still, I would set up an intercooler mister using the headlight washer pump and a relay switch on the dash. With a little experimenting, I think you could find the right nozzle size that would allow the washer resevoir (which is rediculously huge) to last an entire 20 minute session.
Mike O.
#6
Yes all of the above. These cars are all under powered after 110mph
they really hit the air hard after a 100. If your looking for top speed at the bus stop it is all about entry speed into #2 and carring it up through #3 and #4. With the smaller turbos and your line is right you can short shift into 5th between #3 and #4. You need to make that into a short straight. Even with all the advantages the 914 has that wall of air is truly a force to be dealt with. I don't have a speedo, but with the tach and math I did have my personal best last week at a little over 150 and that was because of turn entry into #2 following the cup car. The car will go faster, but mine aren't big enough.
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#10
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Cris, I'm finding an intercooler upgrade is a must if you
want to drive hard. At least an RS4 SMIC. I'm looking into some custom ones from a local shop.