View previous topic :: View next topic |
Author |
Message |
Qik Nip
Joined: 16 Jan 2015 Posts: 130 Location: Kentucky
|
Posted: Sat Oct 07, 2017 3:20 am Post subject: Youtube video of record 924 Bonneville run |
|
|
Not sure if this link pasted below will work from the site, but for anyone interested, here is the video of the run at Bonneville we made setting the G/PRO record in the 924 in August of this year.
If you look closely at the iPhone taped to the dash (running a GPS speed app) we hit 150 at the three mile mark. You'll also see the shift light burning brightly in fifth gear at that point - indicating that the engine was running something above 8,300 for some eight seconds. That RPM should (theoretically) have resulted in a ~165 MPH speed, but the rear wheels were slipping due to aero lift at that speed. Hopefully the spoiler we just installed will end that problem!
Rick
https://www.youtube.com/watch?v=hbX7kL-c7hc _________________ '79 NA 924 Land Speed Car
Bonneville G/CPRO record @ 149.825MPH
Arkansas Mile G/CPRO record @ 138.0 MPH
Great Lakes SCCA SM points champion '09,'10,'11 |
|
Back to top |
|
|
morghen
Joined: 21 Jan 2005 Posts: 8879 Location: Romania
|
Posted: Sat Oct 07, 2017 5:41 am Post subject: |
|
|
Very interesting and different from stuff I'm used to. _________________ https://www.the924.com |
|
Back to top |
|
|
Fasteddie313
Joined: 29 Sep 2013 Posts: 2596 Location: MI
|
Posted: Sat Oct 07, 2017 6:24 pm Post subject: |
|
|
Awesome video, just wish the sound was better but maybe it's my phone.. _________________ 80 Turbo - Slightly Modified |
|
Back to top |
|
|
ideola
Joined: 01 Oct 2004 Posts: 15548 Location: Spring Lake MI
|
Posted: Sat Oct 07, 2017 10:32 pm Post subject: |
|
|
Very cool! Looking forward to your next update!!!!!!! _________________ erstwhile owner of just about every 924 variant ever made |
|
Back to top |
|
|
Cedric
Joined: 27 Aug 2004 Posts: 2608 Location: Sweden
|
Posted: Sun Oct 08, 2017 12:33 am Post subject: |
|
|
Cool clip, especially for us where running on salt flats feels like a different world running with the spoiler will both reduce drag and lift, should yield good results, do you run the stock undertray at the front? _________________ 1980 924 Turbo
www.instagram.com/garagecedric/ |
|
Back to top |
|
|
gegge
Joined: 27 Jul 2007 Posts: 1124 Location: Sweden
|
Posted: Sun Oct 08, 2017 2:53 am Post subject: |
|
|
Tell us more about the engine. Are you revving the stock 2l to 8300? Sounds like you need different gearing if you can do 8 sec in top gear on a salt lake. 165mph is a lot by the way! _________________ Carl Fredrik Torkildsen
924 turbo -81 Carrera GT RESTOMOD
924 turbo -80 Dolomite De Luxe
924 -85 DP kit, BBS RS, M030 and tuned engine
924s -86 Black on black turbo with Fuchs |
|
Back to top |
|
|
Ian89C4
Joined: 01 Apr 2011 Posts: 561 Location: North Carolina
|
Posted: Sun Oct 08, 2017 8:30 am Post subject: |
|
|
Very Nice! Congrats again _________________ Ian Edgerly
North Carolina
Current:
1981 924 SCCA/ChampCar Weissach Race Car ("Serenity")
1987 924S ChampCar Endurance Car ("Der Weg")
1980 924 Euro ("Wahala") |
|
Back to top |
|
|
Qik Nip
Joined: 16 Jan 2015 Posts: 130 Location: Kentucky
|
Posted: Mon Oct 09, 2017 1:53 am Post subject: |
|
|
Cédric wrote: | Cool clip, especially for us where running on salt flats feels like a different world running with the spoiler will both reduce drag and lift, should yield good results, do you run the stock undertray at the front? |
Yes I do. Regrettably the class in which I run limits aerodynamic improvements to lowering and removal of mirrors. Can't even tape up body seams.
Rick _________________ '79 NA 924 Land Speed Car
Bonneville G/CPRO record @ 149.825MPH
Arkansas Mile G/CPRO record @ 138.0 MPH
Great Lakes SCCA SM points champion '09,'10,'11 |
|
Back to top |
|
|
Qik Nip
Joined: 16 Jan 2015 Posts: 130 Location: Kentucky
|
Posted: Mon Oct 09, 2017 2:20 am Post subject: Engine answers |
|
|
gegge wrote: | Tell us more about the engine. Are you revving the stock 2l to 8300? Sounds like you need different gearing if you can do 8 sec in top gear on a salt lake. 165mph is a lot by the way! |
Carl:
It's a naturally aspirated 2 liter with pretty extensive modifications (by the engine builder Michael Mount). In reality all that remained stock 924 was the block and crankshaft. It has a 924 turbo head which permitted installation of larger custom made valves and room for opening up both the intake and exhaust ports, custom made (J&E) pistons (13.6:1), Cunninghan rods, a dry sump oiling system, twin 50mm DCOE Webers via a custom fabricated intake, a custom fabricated stainless header, a custom cam with .525" lift, inner Isky and outer 944 valve springs, and an electronic ignition system. When dynoed it peaked at 8,300 RPM's - although it will pretty safely spin at 8,500.
As for more gearing ... and spinning the tires, we think the issue is aero lift. I'm told that the 924 might be creating ~600 pounds of lift at the rear at 150 MPH. Given the car's 2,400 pound weight, that would mean only 600 pounds on the rears at speed ... ergo spinning tires. Our hope is that the rear spoiler will kill that lift and that the engine will have enough torque to accelerate the car closer to 160.
Rick _________________ '79 NA 924 Land Speed Car
Bonneville G/CPRO record @ 149.825MPH
Arkansas Mile G/CPRO record @ 138.0 MPH
Great Lakes SCCA SM points champion '09,'10,'11 |
|
Back to top |
|
|
gegge
Joined: 27 Jul 2007 Posts: 1124 Location: Sweden
|
Posted: Mon Oct 09, 2017 5:15 am Post subject: |
|
|
Interestering indeed.
The 933 wasn´t able to deliver more than 180 bhp @ 7500. How much does your head flow? 180-190cfm? Making more than 200bhp is difficult given these constrains.
According to the Porsche 924 SAE papers, rear axle lift at 210kph was 80N without a spoiler, due to a "somewhat elevated rear profile" The integrated front spoiler reduce lift to 30N at the same speed. Adding a rear spoiler would reduce rear lift at the expence of increased front lift. But the benefit of an improved Cd from 924 NA 0.36 to 924 turbo 0.34 with the tiny rear spoiler is a major improvement _________________ Carl Fredrik Torkildsen
924 turbo -81 Carrera GT RESTOMOD
924 turbo -80 Dolomite De Luxe
924 -85 DP kit, BBS RS, M030 and tuned engine
924s -86 Black on black turbo with Fuchs |
|
Back to top |
|
|
Cedric
Joined: 27 Aug 2004 Posts: 2608 Location: Sweden
|
Posted: Mon Oct 09, 2017 5:23 am Post subject: |
|
|
gegge wrote: | Interestering indeed.
The 933 wasn´t able to deliver more than 180 bhp @ 7500. How much does your head flow? 180-190cfm? Making more than 200bhp is difficult given these constrains.
According to the Porsche 924 SAE papers, rear axle lift at 210kph was 80N without a spoiler, due to a "somewhat elevated rear profile" The integrated front spoiler reduce lift to 30N at the same speed. Adding a rear spoiler would reduce rear lift at the expence of increased front lift. But the benefit of an improved Cd from 924 NA 0.36 to 924 turbo 0.34 with the tiny rear spoiler is a major improvement |
Didn't the evolved 925 'gt3' 933s have 200-230 hp? _________________ 1980 924 Turbo
www.instagram.com/garagecedric/ |
|
Back to top |
|
|
Qik Nip
Joined: 16 Jan 2015 Posts: 130 Location: Kentucky
|
Posted: Tue Oct 10, 2017 1:35 am Post subject: |
|
|
gegge wrote: | Interestering indeed.
The 933 wasn´t able to deliver more than 180 bhp @ 7500. How much does your head flow? 180-190cfm? Making more than 200bhp is difficult given these constrains.
According to the Porsche 924 SAE papers, rear axle lift at 210kph was 80N without a spoiler, due to a "somewhat elevated rear profile" The integrated front spoiler reduce lift to 30N at the same speed. Adding a rear spoiler would reduce rear lift at the expence of increased front lift. But the benefit of an improved Cd from 924 NA 0.36 to 924 turbo 0.34 with the tiny rear spoiler is a major improvement |
Carl:
Are you saying that SAE paper reported that the rear lift with no spoiler is just 60 Neutons (17.6 pounds) at 210 KPH (137 MPH)? That seems somehow off by perhaps an order of magnitude. Or did I error in my Newton to pounds conversion?
Rick _________________ '79 NA 924 Land Speed Car
Bonneville G/CPRO record @ 149.825MPH
Arkansas Mile G/CPRO record @ 138.0 MPH
Great Lakes SCCA SM points champion '09,'10,'11 |
|
Back to top |
|
|
ideola
Joined: 01 Oct 2004 Posts: 15548 Location: Spring Lake MI
|
Posted: Tue Oct 10, 2017 4:54 am Post subject: |
|
|
Cédric wrote: | Didn't the evolved 925 'gt3' 933s have 200-230 hp? |
Perhaps, but not with the 2.0L. Most of these in the GT class, as far as I am aware, were converted to 2.5L. If they were based on the 2.0L block, they were almost certainly bored and stroked. Will have to go back to Roy Smith's book and the chapter on the 933 program to confirm... _________________ erstwhile owner of just about every 924 variant ever made |
|
Back to top |
|
|
ideola
Joined: 01 Oct 2004 Posts: 15548 Location: Spring Lake MI
|
Posted: Tue Oct 10, 2017 4:55 am Post subject: Re: Engine answers |
|
|
Qik Nip wrote: | When dynoed it peaked at 8,300 RPM's - although it will pretty safely spin at 8,500. |
You didn't mention lifters...I presume you are not using the OEM lifters? They are known to crack at about 7500 RPM. _________________ erstwhile owner of just about every 924 variant ever made |
|
Back to top |
|
|
Qik Nip
Joined: 16 Jan 2015 Posts: 130 Location: Kentucky
|
Posted: Tue Oct 10, 2017 5:46 am Post subject: Re: Engine answers |
|
|
ideola wrote: | Qik Nip wrote: | When dynoed it peaked at 8,300 RPM's - although it will pretty safely spin at 8,500. |
You didn't mention lifters...I presume you are not using the OEM lifters? They are known to crack at about 7500 RPM. |
Good catch...No they're 38.5 mm lifters from a European maker (Ventiltryckare?). Got them from a Swedish outfit named ACM.SE. So far no failures.
Rick _________________ '79 NA 924 Land Speed Car
Bonneville G/CPRO record @ 149.825MPH
Arkansas Mile G/CPRO record @ 138.0 MPH
Great Lakes SCCA SM points champion '09,'10,'11 |
|
Back to top |
|
|
|