I had my car dyno tested again at the PCA Festival of Speed. This was a different dyno but both were the same manufacturer, same software, and same environmental condition algorithms.
The results are within range of 8 hp and an average of 4hp.
Test 2:
High 193.53
Low 190.45
Ave 191.93
Test 1:
High 189.51
Low 185.75
Ave 187.85
I still think that this is a bit lower than the expected ~195hp ave. If you look at the A/F ratio from the second test (top image above), it shows that the engine is running a bit lean. This implies that the cylinders aren't getting enough fuel. I had the fuel pump tested which was fine.
Then we pulled the injectors and sent them out for test with results of low flow rates in 3 cyls. This might be the cause of the lean condition so we had them cleaned and calibrated.
I'll get another dyno test to see if the injector cleaning made any difference as soon as the opportunity presents itself.
__________________
1999 996 C2 - sold - bought back - sold for more
1997 Spec Boxster BSR #254
1979 911 SC
POC Licensed DE/TT Instructor
Good stuff -- thanks for sharing... Did your Butt Dyno tell you anything?
Mike
Quote:
Originally Posted by thstone
Data, data, data!
I had my car dyno tested again at the PCA Festival of Speed. This was a different dyno but both were the same manufacturer, same software, and same environmental condition algorithms.
The results are within range of 8 hp and an average of 4hp.
Test 2:
High 193.53
Low 190.45
Ave 191.93
Test 1:
High 189.51
Low 185.75
Ave 187.85
I still think that this is a bit lower than the expected ~195hp ave. If you look at the A/F ratio from the second test (top image above), it shows that the engine is running a bit lean. This implies that the cylinders aren't getting enough fuel. I had the fuel pump tested which was fine.
Then we pulled the injectors and sent them out for test with results of low flow rates in 3 cyls. This might be the cause of the lean condition so we had them cleaned and calibrated.
I'll get another dyno test to see if the injector cleaning made any difference as soon as the opportunity presents itself.
Here is a short video from Race #3 at the Festival of Speed. Lots of really close racing at the start when everyone is battling for every position. As an amateur racer, it doesn't get much better than this.
Full screen HD with sound for the best experience!
__________________
1999 996 C2 - sold - bought back - sold for more
1997 Spec Boxster BSR #254
1979 911 SC
POC Licensed DE/TT Instructor
Did the 911 miss a shift coming off the oval? He lost a lot of positions.
California Speedway has an interesting format / layout for their roval. Looks like they have several variations that they use.
Transitioning onto the banking is brutal. It was that way at Kansas Speedway too. Very hard on LCA bushings.
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GPRPCA Chief Driving Instructor
2008 Boxster S Limited Edition #005
2008 Cayman S Sport - Signal Green
1989 928 S4 5 spd - black
1987 928 S4 - Granite Green Metallic (Felsengrun)
Did the 911 miss a shift coming off the oval? He lost a lot of positions.
I assumed that he decided to let the front of the Boxster field go by since the 911 is technically in another class - this let the SPB's race it out amongst ourselves without any interference. Also, (another assumption) this let him race his way back up thru the Boxster's and have some fun rather than just time trialing alone out in 1st place (he caught back up to me and passes me at the end of the video clip and then continued to work his way forward thru the field).
Quote:
Originally Posted by husker boxster
California Speedway has an interesting format / layout for their roval. Looks like they have several variations that they use.
Transitioning onto the banking is brutal. It was that way at Kansas Speedway too. Very hard on LCA bushings.
Yes, there are a couple of variations but this one is by far the configuration most often used for sports car racing.
And yes, transitioning onto the banking is really hard on the suspension and there is definitely a trade off - the quickest line though the sweeping left turn before the banking is tight to the inside like I ran but this also places the car at a greater angle of incidence to the banking which results in a harsh transition. Alternatively, you can drive wider through the final corner and then you'll exit more alongside the banking and merge where the angle isn't as abrupt but then you loose speed and distance to the cars on the other (faster) line.
__________________
1999 996 C2 - sold - bought back - sold for more
1997 Spec Boxster BSR #254
1979 911 SC
POC Licensed DE/TT Instructor
I recently tested a SCCA Spec Racer Ford (SRF) at Buttonwillow Raceway!
What an amazing car. There isn't much comparison between a street-based race car like the Spec Boxster and a purpose-built, tube frame, inboard shock car like the SRF. The SRF was an absolute blast to drive.
The suspension of the SRF is perfectly balanced in terms of stiffness vs grip. The car probably has 30% more grip than a SPB due to the much improved suspension and, of course, the Hoosier slicks. Even though the tire width of the SRF is relatively small (185F/205R), the SRF is about 4-5 sec's per lap faster than a SPB at Buttonwillow. That performance comes from the greater cornering ability and a better power/weight ratio (SRF is 135 hp in a 1560lb car = 11.5 lb/hp vs Boxster 200 hp in a 2650lb car = 13.2 lb/hp). Both of those weights include fuel and the driver.
The SRF feels very light and agile. The #11 that I drove was well balanced and didn't understeer nor oversteer. I was consistently over-braking since my brain was calibrated to the much heavier SPB. It really doesn't take much brake to slow a 1560 lb car (that is 900 lbs less than a SPB and 1400 lbs lighter than a stock Boxster!)
There are two things that I want to get out of my racing experience: (1) the opportunity to drive some great race cars, and (2) the opportunity to drive some great race tracks. This is a step towards (1). Oh, and I'm working on (2) also!
Thanks to Alexander Bermudez, three-time SCCA National SRF Champion Mike Miserendino, Mark Bellangee, and the entire MBI Race Team for making this happen and graciously hosting me for the day.
__________________
1999 996 C2 - sold - bought back - sold for more
1997 Spec Boxster BSR #254
1979 911 SC
POC Licensed DE/TT Instructor
Ya, those parallel arms really make a difference in handling. I never understood why Porsche has stayed with the MacPherson strut for so long. Even the lowly Miata has parallel arms!
As you said, the SRF is several seconds a lap faster than SPB at every track, especially with the new engine in SRF3. At Thunderhill, the records are 1:58.7 vs. 2:02.7--4 seconds.
The SRF3 is 135 HP and 131 ft-lbs at the crank for 1560 lbs (Ratio W/(P+T)=5.86), while the SPB is, I estimate, 232 HP and 209 ft-lbs at the crank for 2650 lbs (ratio=6.01). But it's really about the tires, weight, and handling, and not the acceleration.
And then there's the costs. The SRF3 costs 25% less per hour to operate than the SPB. And it's not even the cheapest purpose-built car--Formula Ford/Club Ford and Formula Vee/First are all cheaper to operate per hour than SRF3, and FF/CF are faster than SRF3. Spreadsheet.
I'm not sure why so many people stick with street-based race cars. Is it the perceived safety issues of an open-top or open-wheel car?
Greg
Last edited by Greg Holmberg; 05-01-2019 at 09:33 AM.
Ya, those parallel arms really make a difference in handling. I never understood why Porsche has stayed with the MacPherson strut for so long. Even the lowly Miata has parallel arms!
As you said, the SRF is several seconds a lap faster than SPB at every track, especially with the new engine in SRF3. At Thunderhill, the records are 1:58.7 vs. 2:02.7--4 seconds.
The SRF3 is 135 HP and 131 ft-lbs at the crank for 1560 lbs (Ratio W/(P+T)=5.86), while the SPB is, I estimate, 232 HP and 209 ft-lbs at the crank for 2650 lbs (ratio=6.01). But it's really about the tires, weight, and handling, and not the acceleration.
And then there's the costs. The SRF3 costs 25% less per hour to operate than the SPB. And it's not even the cheapest purpose-built car--Formula Ford/Club Ford and Formula Vee/First are all cheaper to operate per hour than SRF3, and FF/CF are faster than SRF3. Spreadsheet.
I'm not sure why so many people stick with street-based race cars. Is it the perceived safety issues of an open-top or open-wheel car?
Greg, that is a really comprehensive table of race car class info!
I think part of the allure of racing a street-based car is exactly that - it is easy for everyone to relate to it since it looks like a street car. That point notwithstanding, your point about costs is very accurate.
The thought about safety concerns for an open cockpit race car is valid. My wife isn't exactly a fan of open cockpit race cars. But after driving the SRF, I can say that I wouldn't have any safety concerns - the roll bar is super strong and you sit much farther down in the car than it appears when looking at the car.
__________________
1999 996 C2 - sold - bought back - sold for more
1997 Spec Boxster BSR #254
1979 911 SC
POC Licensed DE/TT Instructor
I decided to try Pagid Black RS-14 pads and solid rotors all around this time. These pads are known for incredible grip and being somewhat hard on rotors. In fact, some drivers report that they are either full ON or full OFF and thus, hard to modulate. I'll let you know what I think in a couple of weeks after racing at Willow Springs.
This is a side-by-side pic of the old Pagid Orange front pad and the new Black. The heat turns the originally orange pad backing plate a nice shade of brown!
The new Pagid Blacks...
Everything done and ready to roll!
__________________
1999 996 C2 - sold - bought back - sold for more
1997 Spec Boxster BSR #254
1979 911 SC
POC Licensed DE/TT Instructor
When I drove a spec Boxster at The FIRM it was a big difference over my regular stock heavy Boxster. So to a lesser degree I can feel.what you felt in the SRF. I was braking too early, unused to the better grip of the Toyo RR tires and the 255 fronts, so much grip!
When I drove a spec Boxster at The FIRM it was a big difference over my regular stock heavy Boxster. So to a lesser degree I can feel.what you felt in the SRF. I was braking too early, unused to the better grip of the Toyo RR tires and the 255 fronts, so much grip!
Exactly! Same situation as my experience in the SRF.
In the Boxster, high grip 255's in the front really let you stand on the brakes along with way more grip at corner turn in. That is really how the Boxster should have come from the factory.
__________________
1999 996 C2 - sold - bought back - sold for more
1997 Spec Boxster BSR #254
1979 911 SC
POC Licensed DE/TT Instructor
Linear Mode
