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Rod Penrose's New car project

46317 Views 291 Replies 69 Participants Last post by  twaluminum
Australian drag racer Rod Penrose is building a new bug body style race car!

To be on the track in 2009!

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OK Rod -- Without the actual area of your wing, this is kinda guessing -- If you set your wing at 1* and maintain your speed you should be in the range of 1 to 1.5" of compression -- -- Now this is going to a great chassis tuning device for when you get to one of those iffy tracks where you start getting wheel spin from before 1/8 mile and on -- -- do you have or can you get a chart showing the amount of compression in relation to speed??? Be cool to see at what speed the wing really starts working

You should do a static test on your rear end and see how much weight it takes to get your springs to compress to the amounts you are seeing and then at the same time have you car on some scales and you can see just how much more weight/downforce you are exerting on your tires.... Can't see any downside to the wing, other than running out of tire clearance, but with a little testing you can get it dialed in just right for those ever changing track conditions
Fiatdude , I am 232 lb's , and I can stand on the rear of the chassis above the differential and jump as hard as I can and bounce the car , and the rear suspension will compress about 1/2" . I have the data from the car and I can let you know exactly how much the rear is compressed at any part of the track . The figures I am looking at , is at the point of just before I leave 100% throttle , therefore maximum speed . I have shown my chassis guy and he suggests that the car may be bouncing around in the trailer on the way to the track , so I tried to simulate this by bouncing on the rear of the chassis and could hardly move it . The rear wing is approx 1500 mm wide 220 mm long with a depth of about 70 mm . I just cant comprehend that somthing that weighs about 3 lb's can generate so much downforce . I will now set the angle at about 1 degree and will make it more adjustable for the next outting . The car was quiet good without the wing until I got off the power and the car was a bit of all over the place in the braking area which was a bit hairy . I am still looking at the data and the downforce didn't seem to be slowing me down which seems to be a bit strange , maybe I am still not going fast enough for it to make a difference in speed at the moment , ROD.
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Wow -- those are some incredible facts about how well the wing is working for you -- are you taking data from the front end also??? remember a well designed wing will be quite aerodynamic and not create alot of drag slowing you down, while still giving you that downforce.

If/since you are not losing MPH, the angle/downforce setting on the wing could be used to quiet down the rear end after you let off the throttle on the big end also
Fiatdude , I am logging front suspension as well and it really doesn't alter until I get onto the brakes after the run . The front compresses 12.6 mm under braking and with the chute . I am not launching hard enough at the moment to have any front end extension due to the 1.4 60 ft times . I am pulling .95 G on the launch and -.65 G when I pull the chute according to the data . ROD.
the smoke on the last run was tht the tire rubbing again? Nice easy looking passes, straight, drama free and 932 too boot! Great stuff!! Thumbs Up
Dcuplover , I think the smoke is from a dodgy pushrod tube seal dripping oil onto the exhaust . I seem to keep turning one seal on the head side , in-side-out because it is way too soft and flexible .
I have had a bit of an oop's on the dyno and damaged all of the valves due to the high combustion temps . I have a problem somewhere in the fuel system and the exhaust temps went from 1690 F to 2888 F and don't seem to know exactly why . I had 5 good runs on the track @ 18lb's of boost and 2 days later was on the dyno to put around 200 HP more into the engine and it all went to **** . I have been through the entire fuel system , had the pump flowed with and without the fuel lines and filters and all came back good . The only other thing in the system is the regulator that was sent to be tested and was found to be working well . I have up-graded to a larger regulator on the Turbosmart engineers recomendations , and will be back on the dyno in 2 days time to see if all is well . According to the data , I have heaps of fuel pressure , but seem to bit low on flow . On the day we flowed 4 of the injectors , checked filters , changed sensors and everything seemed to be good , so I am at a bit of a loss as why I had trouble when I didnt change a thing from the track to the dyno . Every time I did a change or looked at something the Lambda was getting worse , it went from .845 to a 1.27 ratio .
The engine was also dismantled , inspected and all was perfect apart from 8 bent titanium valves . The inlets were saved with a light cut , however the exhausts had to be replaced . A big thanks to Dave Folts for the loan of his spare set of valves and Mario from Pauter for all of the imput and getting the new valves done so quickly to replace Daves spare set . The engine is all back together and ready to run , this time with a bit more power . I am hoping to do another test day on the track in 6 days time if all goes well on the dyno , ROD.
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Jeff , I had some good luck on the dyno today , no one got hurt , ROD.


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Was you in the saddle when it let go? Bet you **** yourself?did you manage to get any full runs in?
Sorry to see that, but at least the silver lining is that no one got hurt!
Quote from Rod Don , Chad , thanks for your concerns and info on what can happen . Our Australian drag racing rules are the most stringent in the world and in the pic the full surround is not pressent . Our rules state that the drive shaft must be enclosed in a minimum of .060 wall cro-moly sheet mounted to the car to extend a minimum of 3" forward of the uni joint and to extend passed the driver . I have had some plate rolled in 2 halves and they are bolted together as well as being bolted to the chassis rails extending forward of the uni joint and under the cro-moly tubes that supports the shift buttons . I have decided to make this in 2 halves so only the top half has to be removed to access the rear of the transmission . I am honestly **** scared of the drive shaft rotating next to me and it it now fully covered from where I sit in the car , ROD

I am glad that the quality and craftsmanship of the build were so high and that no one got hurt. Mike McCarthy
Wow Rodney.... That's some serious challenges you have been facing these past weeks.... I had no clue this was going on over there.... Hope all is well for the drag day later this month.... Will see you there, with spanner in hand if you need some help.... A beer if you don't.
Very glad no one got hurt and very glad it happened on the dyno rather than on the big of the track -- -- was that aluminum????

I had one let go on me and it was scarrrry -- the guy who built it had a kid working for him and pulled material from DOM rather the chrome moly -- it twisted up completely like a pretzel when I hit second and pulled itself out of the trans and then proceeded to beat the living chit out everything until I got the rear tires to lock up -- thank god for a drive shaft loop
Thumbs Up
Fiatdude said:
Very glad no one got hurt and very glad it happened on the dyno rather than on the big of the track -- -- was that aluminum????
Correct, It's aluminium, same as what the V8 prostock guys use I believe. The replacement is steel as thats all Rod could get made at short notice, goes back on the dyno tomorrow.
Well , all good at this stage for another run at the track . After 3 days of tuning I am @ almost 32 lb's of boost , 550 HP and just over 1000 ft/lb's of torque at the tyres . This was at the same shop , however with a new dyno installed . The first power run netted me 424 HP and this was enough to get the 1998 lb car to a 9.3 @ 145 on 18 lb's of boost . Now with the extra 125 HP at the wheels I am hoping that I may get down to about an 8.7 second pass . If all goes well I think my limit is an 8.5 run if everything is perfect on the day and the clutch works well . My next outting will be at my first race meeting on April 6 if the weather dosen't turn bad again , ROD.
RodPenrose said:
Now with the extra 125 HP at the wheels I am hoping that I may get down to about an 8.7 second pass . If all goes well I think my limit is an 8.5 run if everything is perfect on the day and the clutch works well .
Madman..... :thumbsup:
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