posted on December 23, 2011 07:24
I love the location of the titanium wastegate dump. The driver side door stickers got tanned from the beginning of WTAC to the end. No doubt the rotary exhaust gas temperatures gave the side of the car a good sun tan.
Here's a close up detail shot of the side skirt. No doubt it's all made out of carbon of course.
Genuine baller spec Craft Square mirrors are used on the GR FD.
The front of the GR FD.
Right after the front splitter, the multiple small tunnels begin. I'm used to seeing two big large tunnels down the bottom of race cars and baller exotics, but I've never see multiple small tunnels like this.
The mini tunnels end just about at the centerline of the rear axle, but do not transition into the rear diffuser which I am also used to seeing on race cars and baller exotics. Aero is one of those subjects where I talk to somebody who knows what they're doing and I just believe them. Sure, there are general laws of aerodynamics, but when it comes to specific applications, it becomes an infinite science (see any F1 car).
The rear body work is a bit funky looking, but falls in line with the "crazy race car" category. The wheel arch is certainly not hella flush and there's far too little camber to be part of the stance nation. Notice the bumps on the underside of the rear wing. Andrew B. or Johnny Mac, if you're reading this, please comment below on WTF those bumps are please.
At the exit of the rear wheel wells are more giant vents to prevent any pressure being built up in the wheel well.
The rear body work is crazy looking and falls in line with the rest of the car.
At the left is a rear differential cooler. The exhaust exits at the end of what appears to be the upper level of a diffuser. Don't forget the JDM shout outs in the license plate area.
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Friday, December 23, 2011 9:02 AM
Those lips around the front hood vents are called gurneys when they're perpendicular to the air flow, and end fences when they're parallel. Surrounding the vents like that creates a low-pressure zone behind the gurneys, which sucks air out of the engine bay more effectively. Basically you trade a little drag for improved cooling and downforce.
I defer to more experienced experts on this one, but those bulges beneath the wing remind me of a trick Oak Racing used on their LMP1 car last year (bottom of page at http://www.mulsannescorner.com/RCELeMans2011.html). Rules mandated a gurney running the full length of the wing (draggy and undesirable for La Sarthe), and the way the rules defined gurneys let them raise some sections to decrease the gurney's angle of attack to the air. Basically it was a way to get around a rule requiring a higher-drag setup, which probably isn't something the Revolution FD needs to worry about. But I wonder if there's a connection.
Friday, December 23, 2011 11:35 AM
Awesome post, i was really looking forward to this one!
I like that airbox setup, wish I could do something similar on my car but I refuse to cut holes/vent the hood in that fashion.
Look forward to part 2!
Friday, December 23, 2011 1:42 PM
This is the article I was waiting to read for a long time.
Thanks for delivery Eric. (I still have to get off my ass and write something about the ALMS at Laguna).
Friday, December 23, 2011 1:47 PM
BTW, the FD is not an old GT300 racecar. It was a regular (yellow street FD) and Aoki san (the honcho of Revolution) bought the GT300 dry carbon off Asemi (Amemiya) from RE Amemiya. So yes, technically IT IS a GT300 car, minus the engine.
Friday, December 23, 2011 7:09 PM
As far as the wing underside, some years ago SuperGT limited wings from dual to single element. People started using all sorts of tricks to generate vortices under the wing. What it does is keeps attached flow just a bit longer and allowed bit more angle of attack/camber on a single element, therefore more downforce. Over time what started as vortex generators morphed into the wavy underside that is now popular. It's tough to get it right but it works.
Friday, December 23, 2011 8:06 PM
With all the custom dry carbon they used I wonder why they didn't make the switch to quillar wing mounts or longer endplates
Based on the last picture on page 4 is Garage Revolution running an exhaust driven double diffuser
Friday, December 23, 2011 8:12 PM
Henry, End plates have tuned heights and they can really only be achieved through testing. Swan neck uprights require similar testing. Aoki san from what he mentioned over dinner, understands the delicate balance and is careful about what he changes until he's confident he will move in the right direction with it.
Friday, December 23, 2011 8:42 PM
I remember reading that Super GT cars make anywhere between 700 to 800 unrestricted, so the GR seems a little underpowered, especially since they were able to lap Tsukuba in the 54's again in less than ideal conditions... maybe it's time to switch back to the 20B, RE Amemiya looks to be heading this way with their new for 2012 Time Attack Hurricane RX7
Friday, December 23, 2011 8:57 PM
Alex: Thanks for the clarification that the GR FD didn't start life as a GT300 car. I've been told the opposite however. Whatever the case, its a damn nice race car.
Andrew: Thanks for the explanation. I wish I understood aero more. One of these days I'll read the whole aero book that I keep referencing sections of and then forgetting soon after.
Henry: Some of the GT500 cars are probably capable of 700+ unrestricted, but the GT300 cars won't make anywhere close to that unrestricted. An unrestricted NA 20B would be lucky if it made much more than 450hp. Battles like GR vs RE Amemiya are what make WTAC the only event in the world that can be called WTAC. Last year it was Sierra Sierra vs. CyberEVO. Since #1 and #2 aren't going to return, the GR vs. Amemiya battle is definitely going to be a part of the entertainment for sure at WTAC 2012. I'm going no matter what.
Friday, December 23, 2011 9:54 PM
Wait why aren't the Cyber and Siera-Siera Evos returning to WTAC 2012?
Friday, December 23, 2011 10:07 PM
Some of the GT300 cars are using the RV8K engine (and others) some shared with GT500 in the new rules for that purpose. They should be capable of a lot of power maybe not over 700 but approaching or near that number unrestricted. However the restrictor rules are in effect.
Saturday, December 24, 2011 12:42 AM
@ Henry, the 13B that is found in the GR makes good power (though maxed out) but it doesn't make a lot of torque.
The 20B found in the RE Amemiya has way more torque compared to the GR FD (much like WRC cars, where they are restricted to 300 HP, the engineers work in extracting more torque out of it).
@ Eric, once I get home I'll post up the link with the whole GR FD built.
@Andrew, any books you suggest reading regarding race-car aerodynamic? (although I understand it's an always-evolving science).
Saturday, December 24, 2011 12:57 AM
Yeah I started my Fascination with J Katz' book 2nd year uni. Hes a bright professor at I believe UCSD. Wish I'd had the pleasure to study under him.
Saturday, December 24, 2011 8:51 AM
Amazing car for sure! The fabrication is top notch! I love it when you get down in to the innards and it is just as if not cleaner than the outside! SOOO many cars lose me when you get in to the details and the workmanship is less than stellar! Safe to say I LOVE this car and build!
Apparently with Aero, once you get to a certain level of study and prep., it is all a matter of designer preference, theory, and method of study. It appears there are an infinite number of ways to produce a similar end result!
Eric thanks for the juice on this build! Oh and why are the top 2 cars not returning....?
Saturday, December 24, 2011 10:37 AM
Starwin/Wes: Both the CyberEVO and Christine have been retired permanently. I think the CyberEVO is supposed to do one more run at a UK time attack sometime in 2012, but after that its done. Both teams have disbanded too. The CyberEVO (Takizawa), Unlimited Works, and Voltex staff that made up the CyberEVO team no longer get along with each other from what I understand. Sierra Sierra disbanded after the 2011 Ferrari Challenge season and I've heard the guys have all found new jobs within the racing community fortunately. With no team to run either cars, I don't think we'll be seeing either of these EVOs any time soon.
Alex: The J. Katz book my buddy Steve gave me a while back to read on the 15 hour plane trip to south Asia is: New Directions in Race Car Aerodynamics: Designing for Speed (Engineering and Performance)
. It's a good book that I reference on occasion although I'd like to read it cover to cover one of these days. I think Katz has other books on the subject too.
Andrew: Thinking about it some more, I believe the RV8K and the engine in the Nissans make about 650hp uncorked, unofficially. In their past lives (used in the original form of racing they were designed for), they would make close to 700hp in qualifying config.
Saturday, December 24, 2011 10:50 AM
That's shame that both of those awesome EVOs are done. Hopefully other teams will be able to pick up the cars and keep the racing. On the other hand, maybe a motorsports museum will purchase the cars and preserve those two important cars. It would be a shame to lose either of them in a crash, so maybe their retirement is for the best.
Thanks for the article on the FD, can't wait to see the rest.
Saturday, December 24, 2011 5:37 PM
Eric, the RV8K is the Toyota engine shared with Formula Nippon. Nissan is using something different, shared with other race platforms including GT1 but thats really all I know about it.
Saturday, December 24, 2011 6:30 PM
Wes, about aero stuff, even if you say there are only two variables to deal with wing location and diffuser angle, this is one of the most basic interactions. 15 angles and a 15x15 grid of wing locations (simplified!) this is 3375 combinations to test. Easily over a year in the wind tunnel on one thing only. So you can see how the experience, knowledge and intuition of your aerodynamicist comes into play. Seeing the smallest detail in one test result can lead him down a path to come up with something extraordinary or drawing on experience to know about all the bits on your car what it will probably like. Throughout all of that, he has to be able to recognize when one test is bad, an anomalous, error or CFD solver limitations. The tools are only tools, just like any other craft. From the outside it looks like there are so many ways to achieve something but in reality there are only a few and one is almost always better than another.
Saturday, December 24, 2011 7:31 PM
I think the engine that Nissan uses is similar to the one in the Zytek LMP1 and Signatech Oreca LMP2... the LMP2 version is called the VK45DE and it is a 3.4L 90 degree V8 that puts out 450bhp at 7000 rpm and 580Nm at 6800 rpm through a 40mm air restrictor
The LMP2 engines have a price cap on the engines of $108,280 so Zytek built cheaper endurance oriented engine parts under Nismo's guidance
The Super GT engine is still a 3.4L V8 but it revs to somewhere between 10,300 to 10,700 rpm through a 29.1 mm air restrictor
Sunday, December 25, 2011 2:55 AM
Andrew: yeah the Toyota RV8K was originally designed for IRL and then moved over to Formula Nippon later on. Pre 2010, the VK45 was still used in Super GT, but the engine that Nissan uses in Super GT now is a clean sheet engine also based on something originally intended for IRL. In their original IRL forms they both made something in the 650hp area on ethanol. In GT1 Nissan is using a stroked VK45 now that they call the VK50.
Henry: the engines in the Super GT Nissans bear no similarities to either of the LMP engines. The Nissan LMP2 engine is a VK45 developed and built by Zytek in the UK.
Sunday, December 25, 2011 1:55 PM
About the bumps on/under the wing, are they like they the dimples on golf balls that are supposed to help it aerodynamically? That said, the shape in your picture looks quite different.
Racecar Engineering magazine did a writeup that mentioned or revolved about it a while ago.
Not sure if this works
Anyone with more insights?
Sunday, December 25, 2011 4:18 PM
YC, read the comments above.
Sunday, December 25, 2011 10:11 PM
Eric - Great insight and detail for the weekend, loved it! I'm hoping your New Year's resolution is to drop more info on upcoming projects (time attack or otherwise) :)
Monday, December 26, 2011 2:54 AM
Andrew, I must have missed it. Thanks.
Monday, December 26, 2011 11:03 AM
@YC - Inserting images works if you use HTML markup. So using something like the markup below will insert the image for you. All you have to do is add an '<' (less than)
in front of the img src code below and paste the URL of your pic between the "" of the img src.
img src="" width="600px" />
Monday, December 26, 2011 3:15 PM
Thanks Eric/ Andrew for the suggestion.
I'll be at Infineon on Wednesday, I'll look for some good reading at the race-shop.
Tuesday, December 27, 2011 2:08 AM
Aero and Carbon awesome-ness! Been waiting to get some close up pics of this art-like build...What an insane TA build. Thanks for all the pics/info, and kind of a bummer to finally have 100% conformation about the UW and SSE-no go. No good to lose the top 2 benchmarks.
Eric, not sure if this is best place to ask, but it is the only place I know to ask you, so I'll keep it less detailed and shorter.... I'd LOVE to get any info on the Christine piston/rod mount I got from SSE, which I am still in shock they sent, it is the coolest gift ever, and they are/were the coolest TA team ever IMO. I will miss following the SSE TA progress. The letter that came with it said it was used in MH0057 (I don't know how many different piston/rod combos were used in the earlier stages of Christine's engine dev, but they were used in MH0057). If not, all good, and thanks for the posts!
Tuesday, December 27, 2011 3:09 AM
Hey Eric, I sent you an email.
Friday, December 30, 2011 12:19 PM
Alright Eric, just saw a picture of you with a camera over on SH's coverage of Tsukuba time attack, I'm looking forward to your heads up!
Sunday, January 01, 2012 2:28 PM
eeeen: SSE sent you a mounted piston? That is ultra cool of them. Engine #57 was rebuilt and improved multiple times over its lifespan so I'm not sure where in that development span that particular piston/rod combo is from. I suspect it is from earlier on in the program which makes it a standard journal rod and a 8.8:1 nominal compression ratio piston. I'm guessing it might be on the heavier side too since the components got continually lighter as Emp kept wanting to rev the engine higher.
Bruce: Yeah Dino was there and got me when I put my beanie up to cool off my ears for a while. Story coming soon!