And here is the car on track, lets give the Mcleran owner some credit for putting his car on track with the temp tag still on it. 1:19.29 was my best time, the p zero slicks had 31 heat cycles on this run, I think I could be in the 1:17 next time with new slicks. I love this car. 6minute video https://www.youtube.com/watch?v=fBWk1XhNJ1g
Johan, Weight. 2875# as she sits, with the tail, fuel, and rear section challenge roll bar. I am wearing full harness, and with slicks, and the possibility of well...errors I didn't feel like having to pay for them again. The car was a bit loose everywhere due to the cycled out slicks but still had a lot of understeer present. I hate to say but it look like the only cure is an increase in mechanical grip in the front. Just like Ferrari did on the GT cars, 9" or 10" front wheels with the corresponding slick sizes. Watkins Glenn is next... Does anyone know any 430/360/Challenge/Scud times on this track...Summit Point Main Course?
One more exhaust video... Here is the car at cold start https://youtu.be/q1AseYY55vY If you notice I made an insulated reflective heat shield that surrounds the air box from the bottom and up the back. It did reduce the air box temp dramatically, I did not have my pyrometer present but after a 30 minute track session the box was cool to the touch vs very hot, I would guesstimate about 30-40 degrees cooler - cost less then $100 and weighs about 3#. Logbook info: April 15th Started Event NASA - 4408 miles April 25th Ended Event Summit Point - 4757 miles Total track miles - 770 miles Total driven miles - 1326 miles The car has used exactly 0 oil. Measures the same on the stick @ op temp. It just makes me smile. No issues, just perfect.
Wow the car sounds fantastic and seems to be running very well too. Not only did you manage to save a scud, but now you're breathing new life into her. Well done!
Thank you guys for the support. The exhaust wasn't unstreetably loud before I added the Ti, that was cat deletes but with the stock valved mufflers, so no doubt it is the Ti crossover responsible for both the volume and the very sweet note. I'm very happy with the car right now except for the understeer noted above. I will focus on getting the handling more neutral with wheel/tire changes. One side note, there is still a difference in the "feel" of the car vs a challenge car that is due to the Scud's rubber flamblocs. It is not objectionable, and actually make the high spring rates feel softer. But it does reduce the exactness of the steering feel. I will not change the flamblocs as this is just for fun, not a max effort race car- it's very nice to have air conditioning and power windows!! But if one of you were interested in converting a street to CH or CH to street definitely factor in those flamblocs, they make a big difference.
Your second post from 08-21-2015, 06:07 AM. I have been following your project and at the begin I didn't think that you can do it. Bravo rmarchjr, you are my hero! It's a great pleasure to see the result, to see your Scud on the race track in its element. Have fun!!
Back today from Watkins Glen. Wow, the repaved track is simply awesome. Very smooth, all the older style non FIA rounded curbing has been replaced with FIA curbs. It really opens up the track for those of you who don't mind running "SCCA" rules style - meaning 2 wheels on the paint is still within track bounds. The bad part for me and others - almost all my turn in reference points were gone. No more concrete patches or old curb markers. Its a bit like a new track even though the track surface itself appears to be dimensionally identical to me. Day1 was rain all morning and slippery the rest of the day. Day2 was much better but I was not able to get myself settled and consistent, I didn't realize how much I was relying on those areas to keep my line. Net results were a bit disappointing to me: 2:06 best and was running there consistently by 2pm. I felt that if I had another full day the car was capable of 1:56-1:57. Oh well guess I need more practice... The Scud was perfect, ran like a swiss watch. No oil usage, temps were low, understeer still present but reduced by softening compression damping in the front. The slicks are wearing very consistently across the face with more wear on left side then right due to more right hand turns. I am only running the car with CST off but still feel that the computer is interfering with torque reduction in some corner exits or maybe I'm just not getting my hands opened up fast enough to compensate for the understeer. Yet to be determined... Needs some new front pads and looks like I will receive my 9" & 11" wheels this week. The increased mechanical grip in the front should be a game changer for this car. I will post up some video in few days.
What are your thoughts on how sensitive height adjustments of your new Penskes affect the over/understeer characteristics. I have read on multiple occasions, modern Ferrari suspension geometry is very sensitive to height adjustments or at least with the factory dampers/springs.
And what wheels did you go with? If I recall correctly, the OEM Scud wheels weight roughly 27-29lbs each. Freshmeat's HRE's weigh in at 18-19 lbs and that is very light for the sizes. If you're up to spend $8k+ on wheels, HRE's are it. There is another "budget" option to consider if anyone else is interested. They are forged Japan made wheels called TWS T66-F . They run about $3200-3500 before shipping from Japan. Fairly light-weight and decent looking. T66-F@TWS Scuderia Sizes (also fits on 360 and 430) 19x11 +28 offset. 21 lbs each. 19x9 +28 offset. 19 lbs each. Image Unavailable, Please Login
Shine, The suspension height adjustment (lowering) did reduce the understeer a bit, but because the stock springs and dampeners were so light resulted in too much weight transfer and some scraping on track (front lip of CH front bumper). The biggest concern when lowering is a reduction of air under the car which reduces the effective downforce. Many CH cars have a small oval opening in the front bumper to increase the volume of air traveling under the car, and counter the reduced airflow from the lower height. 430 CH suspension geometry is identical to stock car but with flamblocs that are rigid vs rubber, so I am not convinced that lowering has any negative effects per se, except for some increased loading (wear) on the ball joints, steering links, wheel bearings. Of course on my track car these get inspected every 4 hours of use so no issue here but maybe not a great idea for a street car which will see thousands of miles between inspections. Now lowered and with 1200#F & 1600#R springs and correctly matched dampeners the cars weight is under control, and some of the understeer can be dialed out. But there is no doubt that the stock tire sizes and the 430 CH slicks are designed for driver safety rather then max effort performance. In slow corners the front end just plows through, very safely. It is purely a lack of mechanical grip up front. Wheel/tire changes should correct it. BYW- generally a larger difference in the front vs rear spring rates also reduces understeer, that maybe the reason my car is handling so much better then stock. These cars are missles, great power and I think Ferrari's tuning decisions are good for most people, under sizing the front tire sizes is the right thing to do for most Ferrari clients, keeps both the cars and the people above ground. I wish you had posted those wheels up about 8 weeks ago. I paid a bit over $5000 for custom Forgelines. Will post pictures when they arrive?this week?. They are very similar to the T66 in your pictures. I'm not sure that 9" fronts will be enough to balance the car, the 430/Scud GT3 used 10" fronts, but may have also required fender modification. I have received the 360 CH caliper mounts from Ferrari, so I can at this point change the front brakes to 360 CH and run 18" wheels instead. I expect that will provide a generous weight reduction (mostly unsprung-smaller calipers, rotors, and lower weight wheels and tires, and of course a much better selection of track tires) I should have enough spare parts soon to build another car from scratch...
I thought the fluid dynamics of things meant the lower the car, the lower the air pressure is beneath the car, causing faster and higher pressure air to be sucked in underneath the car thereby creating better downforce? Same principle as stalling a wing right?
flow rate = Q = Volume/time = Ad/t = cross section area of fluid x width / time = Av. v= velocity Volume = nRT/Pressure temperature being constant then increased velocity = decreased pressure = more downforce but volume being decreased below the car means pressure goes up but velocity affects this as well. in essence lowering the car is really trying to remove air flow in order to decrease lift force more than increasing velocity to increase down force
I'm not sure where the theory vs application meet but... In track testing- when the airflow under the car hit a very low flow or velocity(not sure which) downforce was reduced. I did not see data to prove this. But just look at the 430 GT3 cars, almost all of them have an opening middle of front bumper above the splitter, sometimes open in race form, sometimes closed. The undertray is formed to direct the air under the center of the front axle. I am guessing that a significant reduction of this flow either: 1. Causes the wing(car shape) to stall- less downforce Or 2. Unbalances the downforce on the front vs rear axle. Or 3. Creates too much drag and slows overall lap times. In practice my mechanic who worked for Ferrari on the 360 Challenge race series, was told by Ferrari that too little air entering the front of the underbody would result in a loss of downforce. That's the fact of what they explained to him, now is that the truth? I don't know, but as I don't have a wind tunnel, I will trust the info he gave me above most everything else. Right now I'm changing too many things to make any conclusions. I can say that changing the rear wing from 14deg to 9.5deg reduced high speed understeer (100-130mph) significantly. I will eventually cut the same opening into the carbon front bumper and test its effects on the same high speed corners. But more important is to work the non aero related low speed understeer - just to make a more pleasant driving track car. If you guys have ideas - I'm definitely up to test them in practice....I love this car, it's fun driving fast, the car is equipt with data and I'm a fairly consistent driver.
Depending on which 430 series race car you're referring to, the openings in the front can vary in its function. On the GT3 car it's actually an s-duct, that feeds faster flowing air from beneath the car to the hood surface to help keep the air attached, thereby improving performance. It also helps keep the front-end of the car pinned.
I was under the impression the small and short tunnel right above the factory splitter was designed to increase air velocity by giving the car a winged (technically an inverted wing) shape. The tunnel like shape in the front also has a venturi effect. Increased air velocity underneath the car should result in increased downforce. Decreased volume should also result in increase velocity as a whole. When Ferrari designs the rear to have the muffler sit up high as they can, they are clearing room for a high curved rear diffuser to give the car an even more winged shape (430, Scud, Speciale, 599 fxx) This also increases the velocity underneath the car. Lower air pressure on the bottom , higher air pressure up top = downforce. Keep in mind, unlike most other cars, Ferraris come right out of the box with a negative lift coefficient (downforce), therefore, theoretically, it shouldnt be fighting to reduce lift as the car carries speed. It is actually more planted as it carries speed. Lowering the car should definitely increase the air velocity underneath the car, given no other changes. When some race cars block the front tunnel entry above the splitter, i am suspecting air velocity is decreased. This should be more of a velocity thing than a volume thing. Instead of modifying you 430 CH bumper, you should try putting your Scud bumper back on a simply bolt on a custom splitter where the skid pads are usually bolted and see how it peforms. I know it sounds ghetto, but pehaps some plywood or strong sheet metal should suffice for testing purposes.
