HornetBall's Build #2: Meet Red
12-09-2014, 01:58 PM
#401
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Join Date: Oct 2013
Location: Cedar City, UT
Posts: 2,764
Total Cats: 951
Thanks Rick, that was above and beyond the information I was looking for. Sounds like I didn't make a stupid choice. Just can't wait for the newly revised 15x9's to be released so I can put the 225s on the proper width.
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12-13-2014, 10:50 PM
#402
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Join Date: Mar 2008
Location: Granbury, TX
Posts: 6,301
Total Cats: 696
Getting towards the end of the year. Time to take stock of what I've accomplished with this build.
At the beginning of the year, started with a clean Miata that had some good parts but needed some engineering and love. Got it on track the middle of May but then pulled the engine to fix an oil consumption issue. Back on track in August.
Since August, I've dropped my laptimes by 5 seconds on the 1.7CCW . . . more than one second a month! I'm pretty darned pleased. Here's a chronology:
8/9/2014: 1:30.1 (lap #13 starting around 3:00)
8/15/2014: 1:28.8 (lap #7 starting around 4:35)
I'm following "Miatamoto" in his S2000. Improving skill level plus modifying the line away from the "school" line and more towards a "fast" line.
9/1/2014: 1:27.221
Nothing provides incentive like a 911GT3.
11/30/2014: 1:26.212 (last lap starting around 4:25)
Chasing a legit race car, a NASA American Iron series Mustang.
12/12/2014: 1:25.229
The REALLY fast guys now know who I am and enjoy giving me lead-follows. This is Brett Gabriel, multi-year TX region SCCA Spec Miata champ. He's still quite a bit faster than me in his non-spec practice car, but not so much faster that we're not having fun.
Bottom line, reliable car + seat time = Rapid, Steady Progress
At the beginning of the year, started with a clean Miata that had some good parts but needed some engineering and love. Got it on track the middle of May but then pulled the engine to fix an oil consumption issue. Back on track in August.
Since August, I've dropped my laptimes by 5 seconds on the 1.7CCW . . . more than one second a month! I'm pretty darned pleased. Here's a chronology:
8/9/2014: 1:30.1 (lap #13 starting around 3:00)
8/15/2014: 1:28.8 (lap #7 starting around 4:35)
I'm following "Miatamoto" in his S2000. Improving skill level plus modifying the line away from the "school" line and more towards a "fast" line.
9/1/2014: 1:27.221
Nothing provides incentive like a 911GT3.
11/30/2014: 1:26.212 (last lap starting around 4:25)
Chasing a legit race car, a NASA American Iron series Mustang.
12/12/2014: 1:25.229
The REALLY fast guys now know who I am and enjoy giving me lead-follows. This is Brett Gabriel, multi-year TX region SCCA Spec Miata champ. He's still quite a bit faster than me in his non-spec practice car, but not so much faster that we're not having fun.
Bottom line, reliable car + seat time = Rapid, Steady Progress
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12-23-2014, 01:29 PM
#404
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Catback Comparison/Experiment
I'm recording this for posterity.
When I bought the car, it had an Enthuza-built 2.5" catback with Magnaflow resonator and muffler (R-Speed GT). The exhaust sounds good and makes good power. The only problem is that it's heavy (25 pounds). With a lot of track driving, it sometimes shifts until it contacts car structure (even though I'm using poly hangers). Every so often, I have to get under the car and adjust it.
I decided to try and find a lighter catback. I still wanted to get reasonable noise control so that an intercom could be used on-track. That ruled out most of the Spec Miata exhausts. Flowmaster's dBX system caught my eye and wasn't too expensive. Online reviews said that it was lightweight and noise control was good. It uses a Flowmaster dBX muffler that is kind of a hybrid reflective/absorptive design with built-in vortex cones and absorptive packing (Flowmaster dBX SERIES LAMINAR FLOW MUFFLERS). It uses 2.25" pipe and doesn't have a resonator, so clearance would be improved over the Enthuza catback.
Upstream of the catback is a Racing Beat header with 2.5" collector and an Enthuza 2.5" test pipe (cat deleted). The catback specs:
R-Speed GT (built by Enthuza):
https://www.rspeed.net/RSpeed_Exhaus.../na0-1016.htm:
Pipe Diameter: 2.5"
Material: 304 Stainless Steel
Weight: 25 pounds
Resonator: Magnaflow 14" Absorptive
Muffler: Magnaflow 18" Absorptive
Main Bends: Mandrel 90 degrees in and out of muffler
Flowmaster 819110:
Flowmaster 819110, Flowmaster dBX Series Exhaust Systems | Flowmaster
Pipe Diameter: 2.25"
Material: 409 Stainless Steel
Weight: 18 pounds
Resonator: None
Muffler: Flowmaster dBX 12414310 Reflective/Absorptive
Main Bends: Mandrel 60 degrees in and out of muffler
Fit and Finish:
Both exhaust systems fit the car well. No issues at all with installation.
The R-Speed GT, like all Enthuza products, is really high-quality. The pictured exhaust is about 6 years old and has been on the car for thousands of miles and countless off-track excursions. I'm sure it could be polished up (304SS) to look like new if you're into that sort of thing.
The Flowmaster dBX also seemed to be a high-quality piece, although it's finish is OEM (409SS) rather than flashy.
Noise Control:
This is the part where I post a couple of youtube vids and tell you to go listen to the crappy audio, right? Wrong. You guys know me better than that.
Instead, I got the Real Time Analyzer (RTA) App for my iPod and captured audio spectrums. The iPod location is just below the rear view mirror:
https://www.miataturbo.net/race-prep...7/#post1102015
Car configuration was windows closed and hardtop on with a stripped interior. Pretty much worse case for interior noise.
I captured audio in peak-hold mode during my Virtual Dyno pulls. This records the peak frequencies heard at full throttle from 3000 to 7000RPM. Note that the vertical scales are shifted, sorry about that -- operator error.
R-Speed GT:
Flowmaster dBX:
Like most performance catbacks, both systems let low-frequency audio through. In the middle frequencies, there are significant resonances just below 250Hz and around 500Hz. The Flowmaster dBX really has a hard time with the 250Hz resonance (peaks to about 113dB) but controls the 500Hz resonance better (103dB vs. 107dB for the R-Speed GT). In the higher frequencies, there is no comparison. With easily double the muffled volume, the R-Speed GT kills those high frequencies while the Flowmaster dBX lets them through with another resonance around 7kHz. I would desribe the Flowmaster dBX's sound at full-throttle as "raspier." Both these screen captures were made with the car idling after the Virtual Dyno pulls. At idle, the Flowmaster dBX has the edge (69.2dBA vs. 73.8dBA).
I also made steady-state 70mph audio captures while climbing a slight grade. Again, the vertical scales are slightly shifted.
R-Speed GT:
Flowmaster dBX:
Results here are similar, although the resonance peaks stand out more. The Flowmaster dBX's reflective technology is cancelling a lot of those peaks but it's lack of muffled volume is letting much more high-frequency audio come through. Again, the Flowmaster dBX sounds "raspy" in comparison to the R-Speed GT, but the overall sound intensity at this speed is less (91.7dBA vs. 96.3dBA).
Power:
And, the moment you've all been waiting for. It's been windy here, so it was tough to get a good VD comparison. I did numerous runs. Overall, the Flowmaster dBX system cost me about 5HP. This is representative:
Not sure if the difference is the smaller piping or the Muffler technology. Some say that big pipes on a normally aspirated car cause a torque loss, but that's not what I experienced. My results seem similar to FM's in that regard (http://www.flyinmiata.com/tech/dyno_...ebb_082099.pdf).
Epilogue:
So, in the end I decided that 7 pounds wasn't worth 5HP. I also liked the sound of the R-Speed GT better. It's back on. Anyone want to buy a barely used Flowmaster dBX system?
When I bought the car, it had an Enthuza-built 2.5" catback with Magnaflow resonator and muffler (R-Speed GT). The exhaust sounds good and makes good power. The only problem is that it's heavy (25 pounds). With a lot of track driving, it sometimes shifts until it contacts car structure (even though I'm using poly hangers). Every so often, I have to get under the car and adjust it.
I decided to try and find a lighter catback. I still wanted to get reasonable noise control so that an intercom could be used on-track. That ruled out most of the Spec Miata exhausts. Flowmaster's dBX system caught my eye and wasn't too expensive. Online reviews said that it was lightweight and noise control was good. It uses a Flowmaster dBX muffler that is kind of a hybrid reflective/absorptive design with built-in vortex cones and absorptive packing (Flowmaster dBX SERIES LAMINAR FLOW MUFFLERS). It uses 2.25" pipe and doesn't have a resonator, so clearance would be improved over the Enthuza catback.
Upstream of the catback is a Racing Beat header with 2.5" collector and an Enthuza 2.5" test pipe (cat deleted). The catback specs:
R-Speed GT (built by Enthuza):
https://www.rspeed.net/RSpeed_Exhaus.../na0-1016.htm:
Pipe Diameter: 2.5"
Material: 304 Stainless Steel
Weight: 25 pounds
Resonator: Magnaflow 14" Absorptive
Muffler: Magnaflow 18" Absorptive
Main Bends: Mandrel 90 degrees in and out of muffler
Flowmaster 819110:
Flowmaster 819110, Flowmaster dBX Series Exhaust Systems | Flowmaster
Pipe Diameter: 2.25"
Material: 409 Stainless Steel
Weight: 18 pounds
Resonator: None
Muffler: Flowmaster dBX 12414310 Reflective/Absorptive
Main Bends: Mandrel 60 degrees in and out of muffler
Fit and Finish:
Both exhaust systems fit the car well. No issues at all with installation.
The R-Speed GT, like all Enthuza products, is really high-quality. The pictured exhaust is about 6 years old and has been on the car for thousands of miles and countless off-track excursions. I'm sure it could be polished up (304SS) to look like new if you're into that sort of thing.
The Flowmaster dBX also seemed to be a high-quality piece, although it's finish is OEM (409SS) rather than flashy.
Noise Control:
This is the part where I post a couple of youtube vids and tell you to go listen to the crappy audio, right? Wrong. You guys know me better than that.
Instead, I got the Real Time Analyzer (RTA) App for my iPod and captured audio spectrums. The iPod location is just below the rear view mirror:
https://www.miataturbo.net/race-prep...7/#post1102015
Car configuration was windows closed and hardtop on with a stripped interior. Pretty much worse case for interior noise.
I captured audio in peak-hold mode during my Virtual Dyno pulls. This records the peak frequencies heard at full throttle from 3000 to 7000RPM. Note that the vertical scales are shifted, sorry about that -- operator error.
R-Speed GT:
Flowmaster dBX:
Like most performance catbacks, both systems let low-frequency audio through. In the middle frequencies, there are significant resonances just below 250Hz and around 500Hz. The Flowmaster dBX really has a hard time with the 250Hz resonance (peaks to about 113dB) but controls the 500Hz resonance better (103dB vs. 107dB for the R-Speed GT). In the higher frequencies, there is no comparison. With easily double the muffled volume, the R-Speed GT kills those high frequencies while the Flowmaster dBX lets them through with another resonance around 7kHz. I would desribe the Flowmaster dBX's sound at full-throttle as "raspier." Both these screen captures were made with the car idling after the Virtual Dyno pulls. At idle, the Flowmaster dBX has the edge (69.2dBA vs. 73.8dBA).
I also made steady-state 70mph audio captures while climbing a slight grade. Again, the vertical scales are slightly shifted.
R-Speed GT:
Flowmaster dBX:
Results here are similar, although the resonance peaks stand out more. The Flowmaster dBX's reflective technology is cancelling a lot of those peaks but it's lack of muffled volume is letting much more high-frequency audio come through. Again, the Flowmaster dBX sounds "raspy" in comparison to the R-Speed GT, but the overall sound intensity at this speed is less (91.7dBA vs. 96.3dBA).
Power:
And, the moment you've all been waiting for. It's been windy here, so it was tough to get a good VD comparison. I did numerous runs. Overall, the Flowmaster dBX system cost me about 5HP. This is representative:
Not sure if the difference is the smaller piping or the Muffler technology. Some say that big pipes on a normally aspirated car cause a torque loss, but that's not what I experienced. My results seem similar to FM's in that regard (http://www.flyinmiata.com/tech/dyno_...ebb_082099.pdf).
Epilogue:
So, in the end I decided that 7 pounds wasn't worth 5HP. I also liked the sound of the R-Speed GT better. It's back on. Anyone want to buy a barely used Flowmaster dBX system?
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01-05-2015, 11:28 PM
#409
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Thread Starter
iTrader: (4)
Join Date: Mar 2008
Location: Granbury, TX
Posts: 6,301
Total Cats: 696
Here we go again!
At least I'm getting really fast at pulling the head. Why you ask?
https://www.miataturbo.net/race-prep...ing-out-82462/
Here's what the valves looked like last time:
Intake Valve (trashed):
Exhaust Valve (normal):
Closeup of that Intake Valve:
I expect this set to look similar. They are very recessed into the head. My machinist bud whose shop burned down in the Spring is back in business. He's getting the head this time. To heck with that other guy. Grrrrr . . . .
At least I'm getting really fast at pulling the head. Why you ask?
https://www.miataturbo.net/race-prep...ing-out-82462/
Here's what the valves looked like last time:
Intake Valve (trashed):
Exhaust Valve (normal):
Closeup of that Intake Valve:
I expect this set to look similar. They are very recessed into the head. My machinist bud whose shop burned down in the Spring is back in business. He's getting the head this time. To heck with that other guy. Grrrrr . . . .
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01-06-2015, 01:19 PM
#411
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iTrader: (15)
Join Date: Jan 2007
Location: Murfreesboro,TN
Posts: 2,041
Total Cats: 265
I feel your pain (to a lesser degree). I told my wife I was removing the turbo from my car to make it more reliable and here I an less than a year later pulling the engine because I failed to fully inspect the motor last year.
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02-09-2015, 01:00 PM
#412
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Join Date: Mar 2008
Location: Granbury, TX
Posts: 6,301
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So, rebuilt a fresher used head I picked up off E-bay. Used a different machine shop this time. Fingers crossed.
Got it back together but then got busy with work and dealt with the crud. FINALLY got back on track this last weekend.
Without further ado, track video! I'm running with an M3 on Continental slicks. He loses it at 8:10. I GOT THE VIDEO!! LOL.
Got it back together but then got busy with work and dealt with the crud. FINALLY got back on track this last weekend.
Without further ado, track video! I'm running with an M3 on Continental slicks. He loses it at 8:10. I GOT THE VIDEO!! LOL.
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02-09-2015, 01:19 PM
#415
Glad to see you back on the track!
This weekend was beautiful outside. Seemed like ideal track day weather to me. In my case, ideal weather to spend the weekend outside with the wife instead of doing school work!
Enough sun to heat up the track surface, but air temps in the lower 70s to keep temps down, power up, and avoid buckets of sweat.
I enjoyed watching the M3 lose it in the video. Thanks for posting!
This weekend was beautiful outside. Seemed like ideal track day weather to me. In my case, ideal weather to spend the weekend outside with the wife instead of doing school work!
Enough sun to heat up the track surface, but air temps in the lower 70s to keep temps down, power up, and avoid buckets of sweat.
I enjoyed watching the M3 lose it in the video. Thanks for posting!
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02-09-2015, 01:30 PM
#416
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Join Date: Mar 2008
Location: Granbury, TX
Posts: 6,301
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Now that Donnie's built his new shop after the fire, I'm back with him. So far, so good on the head. But only about 4 track hours in. The other heads would eat their valves in about 20 track hours, so we'll see.
AMEN. Really popular track for those with really expensive cars. The only things to hit are Miatas. LOL.
Glad to see you back on the track!
This weekend was beautiful outside. Seemed like ideal track day weather to me. In my case, ideal weather to spend the weekend outside with the wife instead of doing school work!
Enough sun to heat up the track surface, but air temps in the lower 70s to keep temps down, power up, and avoid buckets of sweat.
I enjoyed watching the M3 lose it in the video. Thanks for posting!
This weekend was beautiful outside. Seemed like ideal track day weather to me. In my case, ideal weather to spend the weekend outside with the wife instead of doing school work!
Enough sun to heat up the track surface, but air temps in the lower 70s to keep temps down, power up, and avoid buckets of sweat.
I enjoyed watching the M3 lose it in the video. Thanks for posting!
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02-09-2015, 01:54 PM
#417
Tell me about it.
If I had a roll bar, I would have already installed it!
Every time, and I mean EVERY TIME I almost get enough extra money saved up to buy the roll bar I want (Blackbird Fabworx NB GT3 4-pt), something stupid happens.
About 6 weeks ago, my wife sprained her ankle. ALLOFIT sprain. Category 3. Doctors said she would have been much better off breaking it. Apparently her insurance sucks, cost us almost $2K for the emergency room visit, x-rays, boot, and physical therapy.
The goal is now rollbar before Hallett '15
If I had a roll bar, I would have already installed it!
Every time, and I mean EVERY TIME I almost get enough extra money saved up to buy the roll bar I want (Blackbird Fabworx NB GT3 4-pt), something stupid happens.
About 6 weeks ago, my wife sprained her ankle. ALLOFIT sprain. Category 3. Doctors said she would have been much better off breaking it. Apparently her insurance sucks, cost us almost $2K for the emergency room visit, x-rays, boot, and physical therapy.
The goal is now rollbar before Hallett '15
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