FXMD Time Attack NSX Billy Johnson

Time Attack Terror: FXMD's Record Setting Acura NSX

By Mike Kojima and Billy Johnson

If you follow Time Attack at all you are probably very familiar with FXMD's Acura NSX Unlimited RWD killing machine piloted by our own Fast Lap Editor, Billy Johnson.  In the 2009 Time Attack season the NSX has given the competition the business in every event it has entered for an undefeated 2009 Redline Time Attack season. Some of the sizzling times posted by the car are a 1:45.247 at Buttonwillow 13CW, 1:18.555 at Willow Springs, 2:13.057 at Spring Mountain and a 1:36.103 at Autoclub Speedway. 

The NSX has been not only winning its class but also taking top honors for the overall fastest time as well. To our knowledge this makes the FXMD NSX the fastest time attack car in North America. A lot of other publications in both print and on the web have featured the NSX but not like how we are, into the deepest recesses of its guts.  A lot of you MotoIQ fans are serious gear heads and are probably curious about what is inside the ultimate time killer.  So pull up a chair and let us take you around and inside what is probably the fastest production based full unibody car in North America.

The 3-1 tubular header for the left cylinder bank is visible here before it feeds into the large TO4Z turbo, the blue anodized cannister is the 44mm Tial wastegate.

The base of any successful race car is a strong engine and the FXMD NSX is no exception. The Acura C30A engine with VTEC is built not for peak power but tractable horsepower over a wide range and stone solid reliably when run hard for long periods of time. The engine has been steadily evolving over the past year into a solid, trouble free package. The engine puts out over 750 whp on high boost.  The block is fortified by Race Engine Development with Darton MID centrifugally cast integrated deck sleeves punched out to 93mm (the stock C32B size) and billet main bearing caps.  An FXMD forged billet crank and rods and CP pistons are used for the reciprocating components.  An unusual semi dry sump system assures lubrication under high G loads.  Two engine driven pumps scavenge the oil pan to an external tank where it is de-aerated, cooled, and pumped back to lubricate the engine by a heavily modified stock oil pump with bigger and stronger gears.   The heads are fitted with Ferrea valves and Supertech valve springs, and titanium retainers.  There have been a lot of mistakes about the engines specs and internals made by other publications but we have been deeply inside of it. To learn more about the engines internals in detail you can read about it here.

fxmd turbo acura nsx
The large oval tube exit is the main exhaust.  The smaller one is the wastegate discharge.  Good wastegate plumbing is important as sometimes over 60% of total exhaust flow can come from the wastegate!  The exhaust discharge location helps the lower diffuser create more downforce by energizing the flow around the exit of the diffuser.
FXMD Turbo system
Here is the FXMD street turbo system being test fitted to our project NSX.  We are including these pictures so you can see how the turbo fits into the chassis with the  diffuser off.  Nearly the same turbo system that powers Billy's  race car is going to go on our project car.  Stay tuned!
FXMD Turbo for NSX
Another view of the street turbo system. 

The engine’s horsepower is fortified by an FXMD turbo system using an equal length stainless tubular header feeding a single Tial Sport Garrett TO4Z Journal bearing turbo. Boost is controlled by a Tial 44mm external wastegate.  A single turbo is used instead of the usual easier to package on a V configuration engine, twin turbos because of a single turbos inherent simplicity, packaging, and efficiency.  Being a mid engine, the exhaust system is just a short piece of stainless tubing with an oval transition to exit. The pressurized air from the turbo is cooled by an AFI water to air intercooler with a Tial blow off valve preventing compressor surge at lift throttle.  Engine management chores are handled by a Motec M48 firing RC1600cc injectors.  A Motec CDI keeps the fire lit even with sometimes difficult to ignite E85 green fuel.

TO4Z Turbo on FXMD NSX
 The Garrett TO4Z is covered by a cermaic blanket to control heat in the crowded rear of the car.
 The Motec ECU and CDI unit are located in the car's cabin away from heat on this carbon bulkhead.
Turbo NSX intake manifold plenum
 This is a larger volume plenum for the engine's intake manifold.
NSX Turbo water to air intercooler
 The trunk area is full of stuff, not luggage.  The lower box is the water to air intercooler, you can see the Tial blow off valve on the intercooler discharge.  The other boxes contain a ducted heat exchanger for the engine oil, the transaxle and the engines air box!  This is a complicated car!
turbo NSX IC heat exchanger
 The is the heat exchanger for the rear mounted  water to air intercooler in the front of the car.  Hot water is pumped from the intercooler to be cooled here.
surge tank for the intercooler
This is the surge tank and reservoir for the water to air intercooler located in the front trunk.  The pump is near here as well.

 From the engine, the power is taken to the ground via an RPS billet twin carbon disc clutch and lightweight flywheel that feed an FXMD modified transaxle.  A close ratio JDM gear set is deburred and WPC treated for strength. For details on the transaxle prep click here.

 Radiator for Turbo NSX
 The radiator is ducted here and the discharge air is routed up and out vents in the hood.  This help generate more front downforce.
Cooling system surge tank
 The surge tank and the bleed point for the cooling system is mounted on a high spot in the engine compartment.
Dry Sump Tank
 The oil tank/ de-aerator for the dry sump system is mounted in the engine compartment.  The FXMD NSX is one of the most complicated race cars we have yet to see!

 An OS Giken limited slip diff was specifically tuned and set up for the cars traction requirements.  It is a little known fact that diff set up is a vital element in dialing in a cars handling.  For details on how this was done, check here.  FXMD modified axles with vented and polished CV joints finish out the drivetrain. 

nsx super ground-
Since grounding on the alloy body NSX is a little problematic, this box heps.
FXMD Turbo NSX RPS clutch
The FXMD NSX uses a RPS Twin disc carbon clutch to contain the Honda engines power.  After this picture was taken, the metal clutch plates were WPC treated.  Billy reports that this greatly improved clutch smoothness.


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Wednesday, February 03, 2010 11:39 PM
What an amazing car. I love articles like this and don't understand why other publications can't understand that some readers care about the details; how it works, how it was built etc. I can't wait to see your project 300zx taken to a similar level. I'm also curious to see how this car will fare in the World Time Attack challenge in Australia. Any word on how they will allow for the disparities in regulations from different nation/classes for that event?
Thursday, February 04, 2010 7:48 AM
The NOS and Beer switches DO have fuses...
Thursday, February 04, 2010 1:15 PM
wpc treated after the clutch was broken in? wouldnt that make it slip?
if it improves the smoothnes of the clutch i should get my metal clutch plates coated too then!
Mike Kojima
Mike Kojimalink
Thursday, February 04, 2010 4:58 PM
WPC is not a coating, I suggest you follow the links and read the article about it.

It might help doing your pressure plate. It works good on pressure plates and LSD's.
Thursday, February 04, 2010 5:53 PM
jjjjjjjjjjj - WPC is a metal surface TREATMENT and NOT a coating. Ideally the clutch would be WPC treated prior to use, but we treated one of our ex-race Exedy clutches for Project NSX. Prior to WPC, the clutch chattered a lot from the carbon on metal contact and in my opinion, wasn't too streetable (although my partner at FX Motorsports felt it was fine for the street -all subjective) but after WPC treating the clutch, it was VERY streetable with zero chattering and has been for the past 2,000 miles.

I highly recommend treating any carbon-on-metal clutches (the metal surface)..

Friday, February 05, 2010 12:17 AM
I couldn't agree more with Fuergrissa.
There are too many garbage-mags here in the States...I wish some of you guys would go back to Sport Compact Car....and actually get payed good money for this type of info's....it's worth gold.
Here in the US we live in a society that is all about flush wheels and slammed cars.....go figure....
Thanks again for the insight Mike, as usual, outstanding job !
Friday, February 05, 2010 1:18 AM
stuntman - what about metallic clutches? i have the os giken str twin plate. when i first installed it it was horrible now it got a lot smoother and im now considering the metal parts to be wpc treated. or is it only recommended for carbon clutches?
Friday, February 05, 2010 5:29 AM
@JDMized - I too was sad to see SCC go but the plus side is we have that core group of tallent here. The best thing you can do to help Mike and the team out is keep spreading those links around.

Great work on the video production guys!
Friday, February 05, 2010 5:40 AM
jjjjjjjjjjj - I do not have experience with WPC treating metallic clutches so I cannot comment with certainty how it will perform. OS Giken clutches are quite good with minimal chattering to begin with. Once yours broke-in, how smooth is the clutch? Do you feel you need further improvement? I think WPC treating the flywheel/metal plates should improve the smoothness similarly to the metal on carbon Exedy that we treated. The different friction materials and differing "Mu" could lead to different results, but I believe there should be a substantial improvement.

Friday, February 05, 2010 5:41 AM
...I forgot to mention:

Unlike magazines, MotoIQ is INTERACTIVE with threads like this - proposing questions and getting instant feedback from the tech guys themselves, and see what others have to say.

Friday, February 05, 2010 11:58 AM
I just updated our top 3 things our visitors can do to help MotoIQ.

Friday, February 05, 2010 6:39 PM
Thanks for the link! I too was saddened to see SCC tank, I'm left shaking my head when I see an accord kitted to look like a lancer, or an old neon with canards and that's it, or the RSX with a big wing mounted backwards. *sigh*
Michael Sheppard
Michael Sheppardlink
Saturday, February 06, 2010 1:54 PM
I noticed that you guys stopped using the PWR barrel intercooler in favor of a larger setup. Has switching to the larger intercooler with longer piping increased boost lag? How much cooler is the charge air temp with the new setup? Incredible article, by the way!
Sunday, February 07, 2010 2:24 PM
I vote for a YO! tuner version hosted by Mike next time!!!
Bob Holmes
Bob Holmeslink
Sunday, February 07, 2010 7:04 PM
What's the angle of attack on the rear wing, if you don't mind sharing. Seems rather extreme.

Great looking, well detailed car. You can see why its been so successful.

Bob Holmes
Sunday, February 07, 2010 7:04 PM
zip ties on the shock reservoirs? thats a no no..is it not?

The other thing, ive read your articles, mike, and you say that you prefer not to use chromoly on your cages beacause its less flexible... why do the use it here? just a matter of taste? thnks
Mike Kojima
Mike Kojimalink
Monday, February 08, 2010 5:28 AM
I did not build this car but I prefer to use 1020 DOM in my cages. Chrome Moly is sensitive to heat with welding and its strength can decline in the heat affected zone of the weld unless its post weld heat treated. Its less ductile as well so in a bad crash, is more likely to break apart instead of bend.

If you start with your chrome moly in N condition and pulse weld with fine mitering and a small electrode and filler, it is probably ok.

I think the wing angle is too extreme. It may be close to stall, The wing has to be designed to run at high angles of attack. More than a 10 degree angle of incidence is probably not going to do much other than add drag and move the COP backwards which probably makes the car feel more stable.

Airflow disruption on the top of the car does tend to activate the diffuser more so downforce is probably slightly increased even if the wing is in stall at a huge penalty in drag.

The team has hired an aero consultant for more fine tuning.
Bob Holmes
Bob Holmeslink
Monday, February 08, 2010 6:09 AM
Mike, that's what I thought also. They'd be better off, both in drag and downforce, with a lower angle of attack. Maybe a multi-element wing in their future. I'd also think about sweeping the rear deck back further and add a ducktail.

I've been reading to much. Its always easy to type and much harder in the field.

Monday, February 08, 2010 9:16 AM
why a journal bearing turbo and not a ball bearing?
Mike Kojima
Mike Kojimalink
Monday, February 08, 2010 10:00 AM
Ball bearings have certain disadvantages, mainly a plastic bearing separator so water must be fed through them to prevent the plastic from melting. More plumbing is a no no in a race car. The plastic part is questionable for reliability in extreme use even if water is run though it. They are not easily rebuildable either.
Tuesday, February 09, 2010 9:35 AM
Splendid article Mike!
(The car is okay too.) ;)

All the aero talk got me thinking. Are under-carriage Venturi tunnels still en vogue? (Some of my aero knowledge might be stuck in the 70's.) I always think it's funny to see a rear diffuser without one since that's what I learned they were for. You know. To help guide the diffusion of air as it exits the Venturi tunnel.

Maybe I'm looking for a traditional vertical Venturi tunnel when the low belly of the car can accomplish the same thing?
Maybe the class rules or physical dimensions of the NSX don't allow it?

Anyway there was so much good stuff in the article I've forgotten if I had other questions.

Truly innovative brake setup! =D
Mike Kojima
Mike Kojimalink
Tuesday, February 09, 2010 12:07 PM
I think tunnels are more of a real purpose built race car thing, where aero is considered first in the design of the car. A race car is smaller and more compact so every bit of the surface can be an aero surface. Most racing rules eliminated undercar aero forward of the rear axle centerline, so tunnels became out and rear venturi kick ups became en vogue.

The single venturi is also more of a production based race car thing because there is room for it.
Thursday, February 18, 2010 6:52 AM
I remember the other thing I wanted to ask.
How is the cage junctioned with the aluminum unibody?
Bob Holmes
Bob Holmeslink
Wednesday, February 24, 2010 2:03 PM
I read in one of my mags that the Sierra Sierra car is owned by a couple of guys that have aero experience, v the setup on this car. I bet this car and driver picks up a bunch of speed and downforce when its tuned.

Mike: I hope you can get them to do some analysis and write up on the experience.

Mike Kojima
Mike Kojimalink
Wednesday, February 24, 2010 3:48 PM
The cage is bolted to the aluminum body.

Look for a in depth look at the Sierra Sierra car soon. Its in Utah so its hard for us to get to but we will do something on it.
Tuesday, March 09, 2010 4:01 AM
Zip ties on the canisters aren't ideal but they work.

Many racecars use chromoly cages and our new cage is no different, which is bolted to the aluminum framerails (the new cage).

Our journal-bearing turbo is archaic and a very old design, we will be using a much more advanced and efficient ball-bearing Garrett/Tial unit for 2010.

The wing's AOA was aggressive but a larger gurney flap and massive decklid spoiler on the car support the high AOA. Look at Daytona Prototypes -which also run very extreme AOA and have massive decklid spoilers. 10* maximum AOA sounds a bit small and i'm not sure if I would believe that its the maximum, even considering the variabilities of different setups out there. We have a new wing for 2010.

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