Street Modified minimum weights for an RX-8
06-09-2010, 11:07 PM
#26
Row faster, I hear banjos
Thread Starter
iTrader: (5)
Join Date: Jul 2003
Location: Charlottesville, VA
Posts: 2,217
Likes: 0
Received 0 Likes
on
0 Posts
With all possible SM weight reduction being done (c/f hood & trunk, removal of rear seats, etc), how low do you think one could get realistically?
06-10-2010, 05:06 PM
#28
Row faster, I hear banjos
Thread Starter
iTrader: (5)
Join Date: Jul 2003
Location: Charlottesville, VA
Posts: 2,217
Likes: 0
Received 0 Likes
on
0 Posts
I currently have three engine scenarios for a street mod RX-8 (see option 3 below):#1 Forced induction 13B
Minimum weight = 2,700lbs
I could go with a s/c or turbo. If I kept the Renesis, I'd buy a built 13B-MSP from Pettit Racing. They add some internal mods that make the engine more reliable for forced induction. I like the immediate throttle response of the s/c, but dislike the fact that it'll have the same peaky powerband as the n/a engine. A turbo would provide much more torque down low (as well as throughout the entire powerband), but there could be some lag to deal with when driving the car on course.
#2 16X (n/a)
Minimum weight = 2,480lbs
This engine is rumored to be making close to 300hp/200tq at the crank (if it ever materializes). With a full "catless" exhaust, intake, race gas and a good ECU tune, making 300+whp/200+wtq should be very doable. I like the fact that the car would have a low minimum weight, but I'm not sure if it's attainable??? This would be the light and nimble option which I like the best...but, who knows if and when this engine would appear in a production Mazda????
#3 MX-5 2.0L engine w/ Turbo
Minimum weight = 2,480lbs
Same minimum weight as the 16X n/a engine, but with a whole lot more hp/tq potential. Because it's a piston engine it doesn't carry the weight penalty that rotaries have. Cosworth makes forged pistons and connecting rods for the engine. Engine wouldn't sit as low or as far back in the chassis as the 13B/16X renesis so the weight distribution/handling would be adversely affected in some way (but it shouldn't be too significant). However, I like this option the least as it "bastardizes" the RX-8, but it is a Mazda engine and a legal swap for Street Mod.
I'm still in the hypothetical stage at this point, and considering my options. Might just buy a GT-R in a few years and keep the RX-8 in STX trim...
Last edited by chiketkd; 06-10-2010 at 05:11 PM.
06-10-2010, 05:40 PM
#29
Registered
Join Date: Sep 2009
Posts: 134
Likes: 0
Received 0 Likes
on
0 Posts
Google came up dry, but just how close is an NC drivetrain to just dropping in an RX8?
06-10-2010, 06:50 PM
#30
the forced induction rotary makes the most sense IMO. You don't need to make mega power (350 hp should suffice IMO), just a reasonable amount with good low end response.
FYI, most CF hoods weigh as much or more than the OE aluminum hood. Better off keeping it, cutting off the reinforcing under-layer, and cutting various duct holes in it while also saving a bunch of money for other things.
FYI, most CF hoods weigh as much or more than the OE aluminum hood. Better off keeping it, cutting off the reinforcing under-layer, and cutting various duct holes in it while also saving a bunch of money for other things.
06-10-2010, 07:25 PM
#31
Row faster, I hear banjos
Thread Starter
iTrader: (5)
Join Date: Jul 2003
Location: Charlottesville, VA
Posts: 2,217
Likes: 0
Received 0 Likes
on
0 Posts
GT2 RS would be WAAAY oout of my price range. Realistic cars that'll be within my reach in the not-too-distant future are a new GT-R, used GT3 as well as a NSX. I like all three of these cars for different reasons.
I've been thinking that as well. However, the 16X is just a big ? right now. Hopefully it sees production and it's as good as they say.
I've been thinking that as well. However, the 16X is just a big ? right now. Hopefully it sees production and it's as good as they say.
06-10-2010, 10:27 PM
#34
Row faster, I hear banjos
Thread Starter
iTrader: (5)
Join Date: Jul 2003
Location: Charlottesville, VA
Posts: 2,217
Likes: 0
Received 0 Likes
on
0 Posts
I did consider that engine, but I'm not sure how hard it would be to take a transversely mounted engine from a FF platform and adapt to work in a FR platform???
06-11-2010, 10:50 AM
#38
^Never done an engine swap myself. But it seems that with either the 2.0 or 2.5, you'd have to fabricate engine mounts, and do all sorts of custom work (such as ECU & harness) so I don't think the net work would be that much different. But I'm sure there would be some differences.
06-11-2010, 01:28 PM
#40
Row faster, I hear banjos
Thread Starter
iTrader: (5)
Join Date: Jul 2003
Location: Charlottesville, VA
Posts: 2,217
Likes: 0
Received 0 Likes
on
0 Posts
Is there a dyno sheet of McKee's car in SSM trim posted anywhere? I've only been able to find one when it was still an ASP car.
Personally, I'd also like to find out the upper limits of a s/c system on a 13B-MSP. Imho, the linear powerband of a s/c would make the car much easier to drive at the limit. With that said, I've never driven a turbo SM/SSM car prepped to the level of McKee's. Only ones I've driven have been STi's and Evos with decent local/regional set-ups (making 350-400whp on aftermarket turbos).
Personally, I'd also like to find out the upper limits of a s/c system on a 13B-MSP. Imho, the linear powerband of a s/c would make the car much easier to drive at the limit. With that said, I've never driven a turbo SM/SSM car prepped to the level of McKee's. Only ones I've driven have been STi's and Evos with decent local/regional set-ups (making 350-400whp on aftermarket turbos).
06-11-2010, 01:36 PM
#41
Jason's comment makes a lot of sense at some levels, but some of us enter these modifed classes to learn how to make a car fast, or to try something that hasn't been done before. Probably not very smart, but the challenge of making a fast car is what drives us.
To that end, if I were to ever make a hybrid Mazda SM car, I'd sooner put a force-fed rotary in a MX-5 chassis than a thumper motor in an RX-8 chassis.
Mmmm, a turbo/SC rotary powered MX-5. Now that would be a fun solo car. Have no idea how competitive it could become, however.
To that end, if I were to ever make a hybrid Mazda SM car, I'd sooner put a force-fed rotary in a MX-5 chassis than a thumper motor in an RX-8 chassis.
Mmmm, a turbo/SC rotary powered MX-5. Now that would be a fun solo car. Have no idea how competitive it could become, however.
06-11-2010, 07:29 PM
#42
Is there a dyno sheet of McKee's car in SSM trim posted anywhere? I've only been able to find one when it was still an ASP car.
Personally, I'd also like to find out the upper limits of a s/c system on a 13B-MSP. Imho, the linear powerband of a s/c would make the car much easier to drive at the limit. With that said, I've never driven a turbo SM/SSM car prepped to the level of McKee's. Only ones I've driven have been STi's and Evos with decent local/regional set-ups (making 350-400whp on aftermarket turbos).
Personally, I'd also like to find out the upper limits of a s/c system on a 13B-MSP. Imho, the linear powerband of a s/c would make the car much easier to drive at the limit. With that said, I've never driven a turbo SM/SSM car prepped to the level of McKee's. Only ones I've driven have been STi's and Evos with decent local/regional set-ups (making 350-400whp on aftermarket turbos).
12-22-2010, 08:30 AM
#45
Row faster, I hear banjos
Thread Starter
iTrader: (5)
Join Date: Jul 2003
Location: Charlottesville, VA
Posts: 2,217
Likes: 0
Received 0 Likes
on
0 Posts
Interesting Street Modified proposal in the January 2011 Fastrack:
LS swap in an RX-8 in street mod.... 
Per the SMAC, the following rule change proposal is being submitted for member comment:
- Replace 16.1.D.1 with the following:
- Replace 16.1.D.1 with the following:
“1. Engine blocks must be from production automobiles. Engines must meet minimum production quantities of 1,000 units built for street use, spanning all models of cars so equipped. * Motorcycle, snowmobile, marine, or other engines of non-automobile design are not permitted. This allows engine blocks manufactured as production units for sale in other countries such as Japan or Germany.”
The intent of this proposal is to allow cross-make engine swaps into Street Modified vehicles, using engines produced in sufficient quantities that replacement parts are readily available. Subframe restrictions are not expanded from the existing rules. (ref. #3313)
12-22-2010, 08:57 AM
#46
Meh, too heavy. Stay 2-rotor NA and use 275 tires, the min allowable weight then becomes low-2200# range. Not sure you can get all the way there, but low 2300# range might be possible in an all out effort. Ultimately turbo 2-rotor will be the max value - min effort entry point @ 2740#, but you better stick with reasonable boost and high octane fuel to keep the motor from popping. Even then luck better be on your side. I still think the lowest possible weight option will ultimately be quickest over the power option.
I actually backed off the "stick with the Reni" comment, been discussing a 13B-PP & MoTeC combo, but the price point is about as steep as a homebuilt 20B effort
world class pro racing setup though, big power buzz bomb
.
I actually backed off the "stick with the Reni" comment, been discussing a 13B-PP & MoTeC combo, but the price point is about as steep as a homebuilt 20B effort
world class pro racing setup though, big power buzz bomb.
Last edited by TeamRX8; 12-22-2010 at 09:01 AM.
Thread
Thread Starter
Forum
Replies
Last Post
