RX-8 to DSP???
11-05-2008 | 09:08 PM
#1
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RX-8 to DSP???
So as to not side-track the STX wheel thread anymore, I figured it'd be best to start this one.
I began a thread on sccaforums here: http://sccaforums.com/forums/1/33096...ad.aspx#330966
I began a thread on sccaforums here: http://sccaforums.com/forums/1/33096...ad.aspx#330966
As the RX-8 is now in STX for the '09 season, the topic has been raised on other forums about whether the car should be re-classed to DSP. The most capable cars currently in this class "appear" to be:
-E30, E36 & E46 3 series BMW's
-ITR
-IS300
-Impreza 2.5RS
The '04-'09 RX-8 is similar in size, weight and whp to the E36 BMW's, but comes with a peaky ITR powerband with a similar lack-of-torque achilles heel. I personally don't see it being dominant in this class, but it'll be course dependent whether one could come out on top.
In BSP the car is a lame dead-duck. There's no way it can compete with even the perceived mid-pack cars such as the S2000, C4 vette or E36 M3.
Thoughts? I'm thinking of writing a letter to the SEB but I'm interested in what others have to say about this...
-E30, E36 & E46 3 series BMW's
-ITR
-IS300
-Impreza 2.5RS
The '04-'09 RX-8 is similar in size, weight and whp to the E36 BMW's, but comes with a peaky ITR powerband with a similar lack-of-torque achilles heel. I personally don't see it being dominant in this class, but it'll be course dependent whether one could come out on top.
In BSP the car is a lame dead-duck. There's no way it can compete with even the perceived mid-pack cars such as the S2000, C4 vette or E36 M3.
Thoughts? I'm thinking of writing a letter to the SEB but I'm interested in what others have to say about this...
11-06-2008 | 08:05 AM
#2
So as to not side-track the STX wheel thread anymore, I figured it'd be best to start this one.
I began a thread on sccaforums here: http://sccaforums.com/forums/1/33096...ad.aspx#330966
I began a thread on sccaforums here: http://sccaforums.com/forums/1/33096...ad.aspx#330966
Just peeking at the national results for s&gs and it kinda looks like Ulllllllllose would have been 3rd had he been running in BSP. I know that might not quite be accurate since the groups run the courses on different days/times... but it does kinda point to an 8 being competive in BSP with a good driver and relatively few adjustments.
Has anyone at a national level tried BSP?
11-06-2008 | 11:21 AM
#3
Anyone have a quick list of what mods are allowed for SP? Would make it easier to find builds with dynos that are close to what's allowed. Without looking I think almost everything up to F/I or engine swaps are essentially allowed but I'm sure there are other significant limitiations. But I know that's not accurate.
Just peeking at the national results for s&gs and it kinda looks like Ulllllllllose would have been 3rd had he been running in BSP. I know that might not quite be accurate since the groups run the courses on different days/times... but it does kinda point to an 8 being competive in BSP with a good driver and relatively few adjustments.
Has anyone at a national level tried BSP?
Just peeking at the national results for s&gs and it kinda looks like Ulllllllllose would have been 3rd had he been running in BSP. I know that might not quite be accurate since the groups run the courses on different days/times... but it does kinda point to an 8 being competive in BSP with a good driver and relatively few adjustments.
Has anyone at a national level tried BSP?
For 2009 there are a number of changes coming, radiator, brakes, A-arms.
This is a very ruff list, and you can get into it more. I would think a Speed Source Koni ST motor would be close to an SP motor for output.
11-06-2008 | 11:36 AM
#5
11-06-2008 | 11:52 AM
#6
Hmm. With those changes you could probably get ~30 HP off the crank over a BS prepped car. Replacing the intake/midpipe/exhaust gets you between 10-15. Throw in a mapped AP (or does that violate the stand alone?) and a pulley disabling the AC and there's another 15. Race seats (removal of rears?) plus lighter and stiffer suspension across the board would probably be more help than the bonus HP. Adjustable MS spoiler could really help on some of the faster national courses.
I don't know if that makes the RX8 a winning car in BSP but it would certainly be competitive.
I don't know if that makes the RX8 a winning car in BSP but it would certainly be competitive.
11-06-2008 | 11:59 AM
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Hmm. With those changes you could probably get ~30 HP off the crank over a BS prepped car. Replacing the intake/midpipe/exhaust gets you between 10-15. Throw in a mapped AP (or does that violate the stand alone?) and a pulley disabling the AC and there's another 15. Race seats (removal of rears?) plus lighter and stiffer suspension across the board would probably be more help than the bonus HP. Adjustable MS spoiler could really help on some of the faster national courses.
I don't know if that makes the RX8 a winning car in DSP but it would certainly be competitive.
I don't know if that makes the RX8 a winning car in DSP but it would certainly be competitive.
11-06-2008 | 12:04 PM
#8
Hmm. With those changes you could probably get ~30 HP off the crank over a BS prepped car. Replacing the intake/midpipe/exhaust gets you between 10-15. Throw in a mapped AP (or does that violate the stand alone?) and a pulley disabling the AC and there's another 15. Race seats (removal of rears?) plus lighter and stiffer suspension across the board would probably be more help than the bonus HP. Adjustable MS spoiler could really help on some of the faster national courses.
I don't know if that makes the RX8 a winning car in BSP but it would certainly be competitive.
I don't know if that makes the RX8 a winning car in BSP but it would certainly be competitive.
Race seats, that would be front only, cant touch the rear.
Spoiler only, no wings, regardless of what Mazda PR calls it the Mazdaspeed unit is a wing - air goes over/under it.
Disabling the AC 15hp? Or do you mean 15lbs pulling it all out?
11-06-2008 | 12:08 PM
#9
Underdriven pulley system that disables the AC (ie. Speedsource pulley set) + the Cobb AP nets you around 15hp. Maybe a bit more.
EDIT: Hmmm.... Second look has TeamRX8 posting that SS claimns 10hp :
https://www.rx8club.com/showthread.p...ey#post1369739
If that's the case then you're probably talking 10 from the pulley and 10-15 from the AP.
EDIT: Hmmm.... Second look has TeamRX8 posting that SS claimns 10hp :
https://www.rx8club.com/showthread.p...ey#post1369739
If that's the case then you're probably talking 10 from the pulley and 10-15 from the AP.
Last edited by RK; 11-06-2008 at 12:42 PM.
11-06-2008 | 12:21 PM
#10
Are the times from Nats that unusable for comparisons? Is that more from the skill of the drivers or more from the track conditions when each group runs? I thought BS led off on a cold track the first day so if anything BS 8's numbers would be lower then most other groups.
11-06-2008 | 01:14 PM
#11
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The fact of the matter is:
1) The RX-8 is very similar in dimensions, whp and weight to a DSP E36 3 series
2) Our a-arms don't gain as much with SP mods as the McStrut cars do
3) Both cars would be capable of winning -- Doug and Elliot are only starting to show the potential of the E46 so that class will speed up in the coming years
4) I can't think of a single car in BSP that's as under-powered as the RX-8 and weighs as much as the RX-8 does.
1) The RX-8 is very similar in dimensions, whp and weight to a DSP E36 3 series
2) Our a-arms don't gain as much with SP mods as the McStrut cars do
3) Both cars would be capable of winning -- Doug and Elliot are only starting to show the potential of the E46 so that class will speed up in the coming years
4) I can't think of a single car in BSP that's as under-powered as the RX-8 and weighs as much as the RX-8 does.
11-06-2008 | 02:50 PM
#12
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After giving this idea more than 5 minutes of thought, if I was running anything other than an E46 in DSP, I'd be most concerned with what that car is going to look like, after being fully developed, and what that means in terms of "pay to play" in the class...
11-06-2008 | 02:51 PM
#13
Hey you're probably right. I think we're talking about the 8 shaving roughly 1.5 seconds off times from prepped BS cars to compete with BSP vs. 1 second to compete versus DSP. It's almost assured that you can get the latter with a hundred pounds is dropped weight, smaller wheels able to support even more rubber, and close to 50hp at the crank. Much, much harder to predict it able to get that other .5 a second with the allowable mods. I still think it could compete on the smaller courses but ultimately the lack of power compared to other BSP cars would doom it on bigger courses.
11-06-2008 | 02:53 PM
#14
11-06-2008 | 03:03 PM
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I don't have time, right now, but margins between a stock class RX8 driven by a National level driver and a fully BSP prepped Evo driven by a National driver are probably going to average 2 seconds on a 60 second course, if I had to guess. Can SP mods make that up? I have my doubts...
We could use relative PAX, but I think BSP is getting a bump this year, despite some sandbagging...
11-06-2008 | 03:34 PM
#16
No way it's making up 2 seconds on a national length course. If that's closer to what would be needed for competitive times then it's no wonder no one's given it a shot. I think 1 second is almost a gimme and 1.5 seconds might be possible but 2 just seems like way too much improvement.
11-06-2008 | 04:06 PM
#17
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This is some of the info I've gathered thus far on DSP BMW's from Bimmerforums:
Low budget E36 DSP dyno (pump gas):
This is what Alex Shchipkov's 2,500lb E30 dyno'd at in 2005:
Here's a post from Terry Fair re: DSP BMW's -- works for a Vorshlag iirc:
Linkey: http://forums.bimmerforums.com/forum...php?p=13405229
I've saved all of this info as I start to gather proof to back up my letter.
Low budget E36 DSP dyno (pump gas):
This is what Alex Shchipkov's 2,500lb E30 dyno'd at in 2005:
Here's a post from Terry Fair re: DSP BMW's -- works for a Vorshlag iirc:
Can't help you on FSP, as I don't have enough interest in that class to pay it any attention (sorry, classes with Hyundais and Sprints in it don't toot my horn). But DSP, that's a BMW class that I do follow and can give you so rough ideas on...
Year / make / model / class / % level of preparation:
1992-1995 BMW 325is, DSP, go for broke!
competition weight : should be in the low 2700 pound range
hp and tq and where the peaks are in the rpm band : 190-240 whp should be attainable with a class legal 2.8L swap, header, intake, and aftermarket EFI
any suspension limitations or advantages in class: any bars, coilovers, camber plates and any number of shock adjustments are allowed. You can't alter pick-up points/strut towers, change the brakes other than the pads/hoses, and the suspension bushing material "must not increase in metal content" (but nylon or delrin is allowed). Stock control arms cannot be altered or modified.
developmental limitations: hmm... the factory EFI could be seen as a hindrance to some that want to do a more radical build-up. you are stuck with the factory longblock limitations, too (stock head, cam, pistons, bottom end). Its also a McStrut front suspension car, so that's always a limitation over a better double A-arm car... but in DSP all the top cars are strut cars
largest tire size usable : the two most popular combos are a 15x10" wheel and the 275mm Hoosier 15" tire, and 18x10" wheel and 285mm tire from Hoosier or Kumho. Both require flares, which means extensive body work and testing. Flares can be the single most expensive upgrade on any Street Prepared car, especially if you want them to "look right".
weight balance : should be near 50-50 from cars we've weighed. Way better than the DSP prepped AWD non-turbo Subarus
max lateral accel : I'd say 1.4 to 1.5 g
max accel and braking forces : braking should be over 1.1 g, accel more like .5 g... in first gear with a good triple disc clutch. This expensive clutch and flywheel set-up is good to free up some RPM/horsepower/rotational inertia, and aids in Pro Solo drag race style launches
anything else you can think of that would be beneficial in the evaluating of cars in class. : lightweight seats are a no brainer. Finding a hardtop coupe saves you time/money/hassles/weight doing the non-sunroof conversion. This is a big, fun class that can be very fast in autocross use!
Cheers
Year / make / model / class / % level of preparation:
1992-1995 BMW 325is, DSP, go for broke!
competition weight : should be in the low 2700 pound range
hp and tq and where the peaks are in the rpm band : 190-240 whp should be attainable with a class legal 2.8L swap, header, intake, and aftermarket EFI
any suspension limitations or advantages in class: any bars, coilovers, camber plates and any number of shock adjustments are allowed. You can't alter pick-up points/strut towers, change the brakes other than the pads/hoses, and the suspension bushing material "must not increase in metal content" (but nylon or delrin is allowed). Stock control arms cannot be altered or modified.
developmental limitations: hmm... the factory EFI could be seen as a hindrance to some that want to do a more radical build-up. you are stuck with the factory longblock limitations, too (stock head, cam, pistons, bottom end). Its also a McStrut front suspension car, so that's always a limitation over a better double A-arm car... but in DSP all the top cars are strut cars
largest tire size usable : the two most popular combos are a 15x10" wheel and the 275mm Hoosier 15" tire, and 18x10" wheel and 285mm tire from Hoosier or Kumho. Both require flares, which means extensive body work and testing. Flares can be the single most expensive upgrade on any Street Prepared car, especially if you want them to "look right".
weight balance : should be near 50-50 from cars we've weighed. Way better than the DSP prepped AWD non-turbo Subarus
max lateral accel : I'd say 1.4 to 1.5 g
max accel and braking forces : braking should be over 1.1 g, accel more like .5 g... in first gear with a good triple disc clutch. This expensive clutch and flywheel set-up is good to free up some RPM/horsepower/rotational inertia, and aids in Pro Solo drag race style launches
anything else you can think of that would be beneficial in the evaluating of cars in class. : lightweight seats are a no brainer. Finding a hardtop coupe saves you time/money/hassles/weight doing the non-sunroof conversion. This is a big, fun class that can be very fast in autocross use!
Cheers
I've saved all of this info as I start to gather proof to back up my letter.
11-06-2008 | 05:05 PM
#18
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I like the DSP idea. I agree there's no chance for the car in BSP or CSP. I'd actually consider running DSP locally if we got it re-classed, just so I could play with suspension and big tires. I'd have to figure out how to legally do a sunroof delete though.
As a note, Jason and I have taken a few runs in kwescott's lightly-prepped BSP 8 here in SoCal. 18x9.5s with 285s, springs, intake, hi-flow cat, etc. I'd guess it was almost a second faster in that config... so I think RK's suggestion of 1.5 seconds improvement over BS is probably a good guess with a fully prepped car.
As a note, Jason and I have taken a few runs in kwescott's lightly-prepped BSP 8 here in SoCal. 18x9.5s with 285s, springs, intake, hi-flow cat, etc. I'd guess it was almost a second faster in that config... so I think RK's suggestion of 1.5 seconds improvement over BS is probably a good guess with a fully prepped car.
11-06-2008 | 05:25 PM
#19
As a note, Jason and I have taken a few runs in kwescott's lightly-prepped BSP 8 here in SoCal. 18x9.5s with 285s, springs, intake, hi-flow cat, etc. I'd guess it was almost a second faster in that config... so I think RK's suggestion of 1.5 seconds improvement over BS is probably a good guess with a fully prepped car.
11-06-2008 | 07:21 PM
#20
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I have no doubt in my mind that a prepped Rx8 would trounce an e46 on anything other than a course full of hairpins.
The 8 has a proper suspension, will be significantly lighter than the BMW's, and can fit as much or more tire than the other contenders. I also have a hunch that it won't be down all that much power in terms of peak horsepower...
The 8 has a proper suspension, will be significantly lighter than the BMW's, and can fit as much or more tire than the other contenders. I also have a hunch that it won't be down all that much power in terms of peak horsepower...
Last edited by ChopsMcgraw; 11-06-2008 at 07:41 PM.
11-06-2008 | 09:56 PM
#21
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Yes, you are correct. Kwelscott had a light flywheel.
Rk thanks for the link. It was good to see an agency power pully get .7 hp with 6lbs of torque.
Didn't realize we ciuld get that much torque.
Maybe some day I'll drop by so Jasson or someone else can check my car on the course.
Same set up as Scott except no pully but I have the Variant 3's from KW w/ AP tuned by MM.
It's amazing to see how much faster you guys can drive my car than what I can do on the course.
Rk thanks for the link. It was good to see an agency power pully get .7 hp with 6lbs of torque.
Didn't realize we ciuld get that much torque.
Maybe some day I'll drop by so Jasson or someone else can check my car on the course.
Same set up as Scott except no pully but I have the Variant 3's from KW w/ AP tuned by MM.
It's amazing to see how much faster you guys can drive my car than what I can do on the course.
11-07-2008 | 06:56 AM
#22
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Is there anything other than Agency Power making any improvement? IMHO, 1hp and 6-7tq is nothing in the grand scheme of things. One can just simply 'drive better' to overcome that HP/TQ deficit.
11-07-2008 | 07:58 AM
#23
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Keith,
Cobb makes an Access Port for the RX-8 now (dyno graph must show estimated crank hp/tq):
In the MAP notes, they claim a +5.5% HP & +6.7% lb-ft gain on 91 octane. More power could obviously be had with a dyno tune -- especially one for 93 or 100 octane.
Btw, here's a link: http://www.cobbtuning.com/products/?id=3812
Cobb makes an Access Port for the RX-8 now (dyno graph must show estimated crank hp/tq):
In the MAP notes, they claim a +5.5% HP & +6.7% lb-ft gain on 91 octane. More power could obviously be had with a dyno tune -- especially one for 93 or 100 octane.
Btw, here's a link: http://www.cobbtuning.com/products/?id=3812
Last edited by chiketkd; 11-07-2008 at 08:04 AM.
11-07-2008 | 08:14 AM
#24
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With that said, the current RX-8 doesn't have the power to run in BSP or the light-weight and small size to run with CSP. It seems to fall in no-mans-land in SP.
Last edited by chiketkd; 11-07-2008 at 08:16 AM.
11-07-2008 | 09:59 AM
#25
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From: SE Mass
+1 I'm starting to think that the RX-8 will be a top dog out-of-the-box and only a high dollar BMW build will be competitive with it.
With that said, the current RX-8 doesn't have the power to run in BSP or the light-weight and small size to run with CSP. It seems to fall in no-mans-land in SP.
With that said, the current RX-8 doesn't have the power to run in BSP or the light-weight and small size to run with CSP. It seems to fall in no-mans-land in SP.
--kC
(Or suck bad enough to get the car moved out of a class)