Was doing some testing at Bruntingthorpe on Sunday to get everything sorted for the 'big' run.
Coming out of last corner onto the straight under power (bout 100mph in 4th) and ripped the centre out of the passenger side outer CV joint.
340ft/lb vs Standard 14 year old CV joint ;-) Lobbed two new ones on now and turned the boost rise down a touch. Reaches 1.8bar at 4400rpm now rather than 3900rpm. Should be fine.Matt
in article bpb2bi$1m9n62$ snipped-for-privacy@ID-199813.news.uni-berlin.de, **-** at snipped-for-privacy@btinternet.com wrote on 17/11/2003 18:00:
Yay!
Noooooo! Is it off now?
Phew! 170 MPH, right? Good luck.
Paul
Not even slightly LOL. Got a bit more work to do first. Holding 1.6bar at
6300rpm, just over 300bhp so it should be doing 171mph on the 6300rpm soft cut.in article bpbhud$1lqikn$ snipped-for-privacy@ID-199813.news.uni-berlin.de, **-** at snipped-for-privacy@btinternet.com wrote on 17/11/2003 22:26:
Ouch! I though 18 mpg on mine was bad. Have you seen the Pike's Peak NG900 Viggen? Your old Swedish brick is going to be a real problem cutting through the air. Once you've got the tuning right on the rolling road, perhaps you need to build a fibreglass front end spoiler.
Paul
Well it lost a lot of drag by flatting the bottom off. A spoiler wouldn't really make it anymore aerodynamic, the ones on the Pikes Peakes cars are that big because their racing up hill into thinner air and need to keep the front of the car down as much as possible. By its design a spoiler "spoiles" the flow of air over the vehicle to reduce the pressure build up and kill lift. As it is and current expected power output it should be good for just over 170mph, providing bits and bobs like bonnets and lights are taped up well. Just need to keep everything crossed for a still windless dry day in early Dec now.
Matt
I'm so outta touch on the racing scene I think my firesuit doesn't even make the dating spec anymore more - but - have you tried to vent air up through the back of the hood over the windscreen yet?..
I saw it done on a 99 turbo once on a GT machine to allow for a full length skid plate. In your case it might allow for two opposing length surfaces under the car and perhaps offset some of that 'big nose' pwob you were mentioning..
You are completely correct to be concerned about it all getting out of shape at 150+ - I would be recording tire temps after runs to see if you are getting proud of the surface unevenly back to front..
My 2cents - and yes - where is brother Grunff?! He'd know what to do about my wreck..
Its a good idea and one I looked into, at the moment though the single lengh non stepped undertray has a bit more development to run and should be fine for this application. Hopefully I can overcome the 'big nose' issue with enough brute force ;-)
Indeed I somehow doubt Saab ever wind tunneled it to more than 140mph and we all know how flat bottoms react when they get some pressure under them ;-)
Tyre temps are consistant nothing more than the odd degree out and never the same tyre reading high/low.
I think it was Enzo who said: "Aerodynamics are for men who do not know how to build engines.." Although he said it with one of those cool northern Italian accents and did come to change his tune eventually.
The temp report is good - means your wing is working evenly all other things being equal.
Look, like I said - I haven't strapped on a five point in so long my tackle has finally descended - however I would be easing into 150mph and beyond very slowly over a season myself. The great problem with crisp aerodynamics is that they work just as well off the pavement as they do on.
J Dexter - webmaster -
I can't be the only one thinking how cool that would have sounded ;-)
Indeed
Been slowly building up the speed of the car for 6 months, prob around 2 hours a week on the test track.
No argument with that one!!!
Or that one!!, Worst crash I've had was putting an AX GT backwards into a tyre wall at speed, broke a finger and compressed my spine. After that you don't half take a lot of care over the setup and safety of the car.
Well lets put it this way if it does get airborn at 170+ your not going to have much time to think "Oh Dear" ;-) Hence why safety is beyound paramount on this one.
Sorry brother Faulks - I'm singing to the choir. Having just stupidly greased a beloved 9000T and looking down the barrel of cheapo NG900 5 speed (no T) - it is on my mind..
Your choice of C900 will inherently limit a number of problems relating to excursions off the line at most any speed - basically a very a good skin design to mount a cage in. The only extra trick I've seen and not mentioned was to extend the cage around the floor along the fire wall to keep the wheel wells off your feet in the event of disaster.
That round front windscreen should go a long way to keeping drag under control as you get beyond 160. But I would be concerned about the rear end lifting as you get into that range as I've always felt it makes for a vortex over the rear quarters and my overall take is that you may have to eventually lower the roof to make 170+ - but at that point you are back to square one on the belly math..
Just how much have you chopped out of the engine to lighten it? Rods and crowns of course - have you looked closely at the crank lobes yet? Thar be dragons - but you might well be able to squeeze a extra 3-500 RPM out of the mains if you can carefully lower the weight in there.
Here's a link to a very interesting PDF on my server regarding a Mondello
403 Olds block build out that might be useful. It's not a great scan, nor a SAAB engine of course - but if covers some interesting oiling problems regarding high RPM builds.ftp://gmc: snipped-for-privacy@ftp.dexterdyne.org/UnsungHero.pdf
J Dexter - webmaster -
Sorry brother Faulks - I'm singing to the choir. Having just stupidly greased a beloved 9000T and looking down the barrel of cheapo NG900 5 speed (no T) - it is on my mind..
Your choice of 900 will inherently limit a number of problems relating to excursions off the line at most any speed - basically a very a good skin design to mount a cage in. The only extra trick I've seen and not mentioned was to extend the cage around the floor along the fire wall to keep the wheel wells off your feet in the event of disaster. Keeps the floor down too..
That round front windscreen should go a long way to keeping drag under control as you get beyond 160. But I would be concerned about the rear end lifting as you get into that range as I've always felt it makes for a vortex over the rear quarters and my overall take is that you may have to eventually lower the roof to make 170+ - but at that point you are back to square one on the belly math..
Just how much have you chopped out of the engine to lighten it? Rods and crowns of course - have you looked closely at the crank lobes yet? Thar be dragons - but you might well be able to squeeze a extra 3-500 RPM out of the mains if you can carefully lower the weight in there.
Here's a link to a very interesting PDF on my server regarding a Mondello
403 Olds block build out that might be useful. It's not a great scan, nor a SAAB engine of course - but if covers some interesting oiling problems regarding high RPM builds.ftp://gmc: snipped-for-privacy@ftp.dexterdyne.org/UnsungHero.pdf
J Dexter - webmaster -
We do this on all the racecars and after the Astra incident it proved to much more than worthwhile.
Very good idea! At the moment my 900 is mainly a demo for what we can do. Theres no cage but there is a considerable amount of re-inforcement to the standard shell - Again why not going flying is on my mind!!
I'm hoping some refinements to the rear diffuser will kill the lift, whilst the shape of the C900 is gorgeous that large rear end with its steeply sloping hatch isn't much in aerodynamics terms.
Max RPM on the current engine is 7000rpm, on the last dyno running low boost it made 307bhp @ 5900rpm. My calculations reckon I need 340bhp'ish at
6500rpm to do it. Thats what this fridays dyno session will be for.Many thanks thats interesting reading!!.
That's kinda what I was thinking about when I mentioned lowering the roof. If you get that last flat foot of hatch off but still retain the basic roofline angles - you end up with a very, very clean trailing edge to work on. I should more correctly have said 'chopped the rear quarters and front pillars to lower the roof'. But again - it will completely change how the underside is working - which supports your focus on max engine output.
It's an interesting problem really - at the output ratings noted in your last post you want to keep as much leverage on the front wheels as possible to limit wheel spin. In the C900 this is naturally helped by the engine layout. On the other hand - as you don't have a lot a weight in the back to hold it all down - less as pressure builds up - you chance a nasty snap to the left or right if it gets turbulence under the machine and lifts the back up at the end of a straightaway or running high speed corners. Here's an interesting history that touches on the subject:
My take is that active suspension kinda solved half of the problem in that springs/shocks then work with ever changing effective total weight in real time so it 'handles' well enough to ignore most variations in pressure - but - unless you know an F1 guy from the early 90's with a wreck and an interest - you are unlikely to find anything applicable to the SAAB. It kinda all went into making Mercedes more comfortable over potholes. Crap and half - eh?
A pleasure. That's what powers my other love - a fire breathing front wheel drive GMC 26 foot motorhome. I'll make a land speed run with her one day (har-har).. :) ..
Salutations:
So - how'd it all turn out at the dyno? Weren't you supposed to be in for a test pass last weekend?
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