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This is all what I would lump into "phase 2" of my project. Once the powertrain is all sorted and reliable, I'll start on aero modifications.

The rake will be increased to ~0.5 to 0.7 degrees relative to the ground plane. This requires a 20-30mm ride height difference front to rear. The front will be around 100mm, as measured per the normal techniques.

I have a swan neck mount wing from DJ Race Cars waiting to be installed. It's a SM132 element, 300mm chord, 1640mm width. The wing will have multiple mounting positions, again depending on time trials rules... but in general, the wing will be mounted 6" above the roof line. I may augment the wing with a second element (not class legal for most of the time trial classes) for times when I just want to achieve a maximum downforce configuration.
One of the problems I have is figuring out how to optimize various aero elements. I have studied some books and read the Aerobytes articles in Racecar Engineering. All the plans you have agree with what I've been reading. My complaint is that I don't have any numbers or sense of the level of impact that each element of aero has in the overall scheme. For example, the height of the wing. 4" above roof height is quite high whereas testing various heights and setbacks show that there is a pumping action that assists the underside aero with a lower and/or further set back wing. How does one without lots of testing determine even that one variable of wing height? What amateurs like us need is some feel for the level of impact each proposed change can make. One option I debated was getting into the CFD, which requires a fair amount of computer power/time, CAD experience, and expertise that comes from trial and error. But I already sit in front of a computer too much now.

What I would like is an expert that could tell me for each element on a list of proposed changes whether that change would make a 20%, 10%, 1%, -10% difference. That would give me a sense of whether it was worth trying the change. Another option is to build three wing mounts and then do some testing of each with perhaps suspension height logging in order to determine the effect of each change. Repeat for each proposed change. That would be a lot of fabrication and testing.
 

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Discussion Starter #182
@RoHo - we've probably been reading the same books :)

Your points are all valid.

Regarding wing height, specifically, I decided to go with a tall mount approach to two reasons. 1. Getting the wing out of the roofline wake will allow it match intuition better and take some of the guess work out of "what is the real angle of attack?" 2. It seems like you want to move the wing as far back as possible to maximize the interaction with the underbody aero. The farther aft the wing is mounted, the more moment is generated by the wing downforce. This moment reduces the load on the front axle, shifting the downforce balance rearward. So, unless the underbody aero downforce increase is enough to negate the force reduction on the front axle due to the applied moment, the front grip seems like it will be reduced by the wing/diffuser/underbody interaction. My assumption (maybe I'm wrong!) is that front downforce will be more difficult to achieve whereas I can always add more rear wing. So, I'm largely treating the wing and underbody as separate aero devices by creating a large vertical separation.

As you said, without proper testing or analysis (validated analysis would be really time consuming)... it's all just keyboard design.

I recently came across Simscale.com as an interesting option for cloud-based CFD analysis. There are a few public models of an Elise. No idea whether the surfaces are accurate, but it looks like an Elise. Perhaps you could run some symmetry plane analyses with emphasis on very specific regions, like a wing/underbody interaction study.
 

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@jdawson Being around Aero engineers too much and consulting at the rolling road wind tunnel, they tell me that by creating better air flow under the car will also create more front down force.

Later,
Eldon
 

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Discussion Starter #184
Well, maybe that's an aero study that would be worth working on.
 

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I can tell you that you are going to want to be careful with the splitter gap. The minimum that you want to get this is around 1/8" and the closer you can keep it to that the better. Also, if you go below this or seal it to the track, you will most likely stall the splitter which can create a very unwanted oscillation in the front of the car. It will feel as if your rotors are wrapped. I did this on my Cup-R and had to install bump stops to prevent this. We have also seen this in testing at the tunnel. I have it seen it so violent that a it can make the front tires leave the ground. I can also tell you that most of the high downforce road race cars will run bump stops all the way around.

Later,
Eldon
 

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RoHo, you're running into the problem that all bleeding edge folks run into.... You're on the bleeding edge! :) At some point, there are no "experts" except the one in the mirror. At that point, you just have to dive in and start testing. It is slow, painful, and expensive. I've been working with jdawson with years of lessons learned on our Blackwatch Racing XP car, but not on Aero. Our Aero is quite primitive compared to what he is doing. It makes sense as the nuance of Aero is lost in AutoX, plus our ruleset is restrictive. When he wasn't sure or didn't like an existing direction, he went in his own. Some will work, some won't but that is half the fun.
 

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Discussion Starter #188
@jdawson are you going to use the Haltech to run an E85 setup? Will this pass an OBD2 emissions test?
Yep. The flexfuel sensor is connected and functioning through a digital input. The Haltech won’t pass emissions. The only tuning option that I know of that will pass an OBD2 plug-in test is a T4e flash. The limitation there is tune customization and optimization.
 

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Discussion Starter #189
OK, first things first... then we'll get to more details.

https://flic.kr/p/2k8oeuK
It runs! Oil pressure is healthy. I've only ran it for a total of maybe 45 seconds. More to come on that...

Wiring all done, tested and tie wrapped away. It's fairly clean looking, but definitely busy with all of the additional electrical modules and sensors.


Here's a more clear view of all of the inlet plumbing. Again, lots going on here. You can see that I tried to torque stripe every fastener along the way. This will become important later in this post.


The whipple oil site plug is not the best design. It's just about impossible to torque this thing as designed. I turned a socket down until it would engage.


Here's a couple images of the SC gearbox vent I'm trying out:


Temporary mounting of the breather until I can determine if it works or not.


Before starting it, I went through the process of priming the oil system. It was making a healthy 27psi while cranking. I also pulled the plugs and connected a timing light to the coil pack on cylinder 1. A minor adjustment was needed in the calibration, but that's not unexpected given all of the valve train is new and the old timing chain was beyond the service limit.

Here's the engine bay all buttoned up just before firing it up for the first time.


Now to the bad... not terrible... but not great. On startup number 2, after making a small change to the closed loop idle parameters, the engine decided it didn't want the water pump pulley installed any longer. A couple of quick loud clangs were enough to make me think something catastrophic had happened. So, I pulled myself out of the driver seat, expecting to see oil scattered everywhere and coolant dripping on the floor. But, nothing like that was to be found. The serpentine belt wasn't taut, so that was where my attention focused.

No notable damage to the belt:


But, the water pump pulley was no longer attached to the water pump. Huh.


I could only find three of the four fasteners & washers, which was odd. And, they're lacking any torque striping. Somehow I missed this in my inspection before starting it. With so many changes made, it was bound to happen somewhere. So, the question is... "were they torqued to begin with?" The washers suggest load was applied at some point... but the wear marks are quite uneven.


More to come in the following days. I don't think there is any real damage done. No holes in the block, no leaks.
 

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Such a clean build, very impressive!! Looking forward to the tuning phase!
 

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Awesome! Enjoying this post a ton. FWIW, I always loc-tite those bolts for the WP pulley. I don't torque them because it is really hard to get a torque wrench in there.
 

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Following this build is like we are watching a close family member.
We're all involved and excited to see its development.
Great work on all fronts!
 

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Incredible work! I enjoy watching all the updates and seeing all the custom fabrication required!
 

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Discussion Starter #194
My theory is that the water pump pulley fasteners were hand tight and backed out quickly while the engine was running. Strange for two reasons, I wouldn't expect them to back out so quickly and also strange that I didn't torque them as soon as they were installed. But, they didn't get the torque striping treatment, so something was off in general.

But, now I know belt changes are possible with the engine in-situ. Three of the four water pump pulley female threads were OK. The fourth was likely the last bolt to fall out and took the most abuse as a result. I managed to clean it up enough to get a fastener in, but it's not 100% healthy. Hopefully it'll stand up to a life of normal use. The fastener threads were all OK. During reassembly, I used some HV200 hardened washers.

Unfortunately, I incurred the dreaded "tensioner hex stripping" issue during reinstallation of the belt. Whoever thought it was a good idea to use cast aluminum for a feature that would see decent levels of stress was wrong. Also, unfortunately, this piece can't be easily removed/replaced with the engine installed.


There is an alternate method, thankfully. Remove the tensioner spring/damper from the tensioner arm and use a clamp to compress it during reinstallation.


If you have to use this method, do yourself a favor and file/grind a flat onto the bottom surface of the aluminum housing. If you don't, chances are the clamp will want to slip off as you increase the force applied to it. Ask me how I know.


And with that complete, we should be back in business.


I promise there are four fully torqued and torque striped fasteners installed in the water pump pulley this time. Promise.

For those interested in what I'm using for torque striping, this is my current favorite. It dries hard/brittle and easily shows a fracture if there is relative motion between the two pieces.
 

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Discussion Starter #196
Serpentine system is all fixed and I was able to spend some time working on the idle. It's going to be a fun process of tuning this beast of an engine... very different than the stock engine which required low close loop idle gains and would sit happily at 800rpm. Now... not so much. I've had to increase the base duty cycle allowable by 3x, the integral gain by 4x and up the target RPM to 1400rpm. It clearly needs a lot more work, but at least I don't have to baby the throttle to keep it idling.

 

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I LOVE the individual EGTs you have on each header runner. I definitely want to do that in the future......
 

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I LOVE the individual EGTs you have on each header runner. I definitely want to do that in the future......

As far as the hex goes, I made up a dedicated tool, which is a piece of hollow round bar as a handle with a 19mm 6pt hex welded on at the right angle. Used it for years.

For those of you out their playing the home game, ALWAYS use a 6pt HEX on the tensioner arm. Honorable mention: Long prybar underneath the arm. I need to get a clamp though, that looks like the best way for the finicky 10 rib.
 
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