Time Attack Build Blog

[hpexperts]

this is just sick!!! good luck keep posting please.

 

[my2AWDgst]

How will the headlights fit Drew?

 

[gixxerdrew]

Just like on the supra with a little step on the sides of them
http://douro-oni.com/images/DSC_0348copyLarge.jpg

 

[questhe]

Hey Drew, thanks for having me over. I hope I can make it out there for a full day to help out sometime.
Dietrich

 

[red1g]

Very nice,you should post this up on the Time Attack Forums also.Time Attack Forums - Powered by vBulletin

 

[gixxerdrew]

I'd rather I surprise some people at the race I'm kind of hoping they don't all catch word of this imagine the embarrasment if we're not that fast at the first races (fairly likely actually). I'd prefer to be under the radar.

 

[gixxerdrew]

small updates, thanks again to twicks for the idea on the upper control arms to put the markings. I figured out some band clamps meant for hydraulic lines to use for retaining the ball joint boot I'll get more info when they arrive

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additional suspension parts from the machine shop. These are some custom upper and lower standoffs for the DG style hats to work with my setup.

these are the upper standoffs

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lower standoffs

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[gixxerdrew]

I <3 my motec, I need a t shirt that says that.

My pressure pump is an aeromotive eliminator which has its own control unit, what I been working on is a lift pump, a stock configuration in tank pump for lift to a swirl pot. For the lift pump to manage voltage consumption I got the motec setup so that its running pulse width modulation on the fuel pump output based on fuel consumption (this is a built in feature on motec) and use a solid state relay for the lift pump activation.

The motec also kicks the aeromotive controller into high voltage mode when you reach a decent amount of boost.

One of the problems on the car is the absurd torque hit. Motec has this handled as well. There is a full 3d table for boost control based on throttle position vs RPM vs boost targets and then a global adjustment. My manifold likes to creep on boost. If you set it direct to wastegate it starts at 18psi and ramps to 23. I'm working on this to make it easier for the driver to control the car as well as so that traction control does a little less work cutting spark events. I'm concerned about combustion events in the exhaust manifold.

This is kind of good to manage torque but you would only want it to do that when you want it to do that, not all the time. So I set up a 3d table for boost control so if I am at lower throttle positions I'll get the natural curve that the boost has (lower in lower RPM) and then at full throttle it will give it everything to the target boost I select. Once I have the tables dialed in I just use the global adjustment to increase or decrease the boost target.

Here is the spreadsheet I worked out for boost target vs rpm vs throttle position so you can see the curves I decided on for initial testing.
http://home.tiora.net/andrew/MoTeC/boostVSTPS.xls

so these tables are designed for low boost and then I'll just adjust up from there globally.

 

[gixxerdrew]

A little more progress to report especially for the guys (like me) who find body work really interesting

basic fender shape compelte

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close up

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Louvers are up next on the agenda

the car's stance is very aggressive now

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rear shot to see how big the opening is

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work begins on fiberglass mold for the side skirts

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size comparison of the old and new radiator inlets

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Nick tracking down the noisy gauge signal problem

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Strangely it was an issue with engine grounding we were able to get it working right but just in testing, have to order some more parts to make some custom engine grounds and go back next weekend.

Another shot of David's work with the fenders

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[hpexperts]

sick built, dude really sick.

 

[gixxerdrew]

Thank you! Trying to make it even more sick day by day

 

[snowborder714]

Can you share your surge tank designs? I know you mentioned you had something in the works in the thread about surge tanks, but haven't seen anything yet.

Also, where do you plan on mounting it?

 

[fulanititoo8198]

I saw the 245's I got a little sad inside I was like that's it. Then I see the 285 that's more like it holy Shut. Nice I'm glad your taking the dsm game to another level.

 

[gixxerdrew]

Can you share your surge tank designs? I know you mentioned you had something in the works in the thread about surge tanks, but haven't seen anything yet.

Also, where do you plan on mounting it?

The surge tank is still in the works, its getting sort of tabled I have to focus on what I absolutely cannot make the first race without right now since theres still a shot at making it.

I saw the 245's I got a little sad inside I was like that's it. Then I see the 285 that's more like it holy Shut. Nice I'm glad your taking the dsm game to another level.

you should see it with R compound NT01's on, even more crazy looking

 

[Flash]

Wheels?

 

[gixxerdrew]

what do you mean?

Do you mean what wheels are they?

I bought all of them from wheeldude.com. I'm really impressed, they are very very nice looking wheels.

fronts are
18x10 rota boost, 20 offset
rear:
rota boost 17x8.5 35 offset

 

[projecTSI]

Unbelieveable. Everything looks so clean, can't wait to see some pictures of the finished widebody!

 

[gixxerdrew]

Unbelieveable. Everything looks so clean, can't wait to see some pictures of the finished widebody!

Thanks a lot! Yah I cant wait to see the finished product as well.

 

[hpexperts]

very nice show more pics when you can.

 

[e85_4g63]

you should see it with R compound NT01's on, even more crazy looking

I wanna see em' Great work so far

 

[gixxerdrew]

Also the 285 on 20 offset 10" wheel clears the upright JUST BARELY, which is exactly how I like it about 2mm clearance in case anyone else goes widebody that fit perfect I was happy I got it right on the first try.

Thanks guys, I made a mistake and specified the louvers too big, the body shop has to redo the cuts on all of them. I'm a little embarrassed about that mistake it may put us off schedule for making the first race

 

[gixxerdrew]

When you can't afford to get in a wind tunnel... you use crude calculations

I'm really into data acquisition stuff enough that I'd rather do it than drive the car. I made an aero worksheet for I2 this morning, the other standard worksheets are really good. Copied over my formulas from the old data system. I2 is amazing.

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(click to zoom)

Next up is a math channel for drag calculation then I can show power avail for acceleration down the straight and compare it to the G force/ accel rates on a straight then work out a theoretical top speed. Then work backwards to your other calculations then and adjust them for accuracy. Not the best method but definitely you can get some good data from changes on the car. In land speed I spent a lot of time on that sort of thing and following dust patterns on the body and studying high speed photos like the old guys do.

After the aero work is done on the car I'll calculate my drag Cd from roll down testing so the numbers will be as accurate as possible. I usually do this work on the dry lake, running in a few different directions to try and eliminate wind, but this data is from a road course so I just pick a spot on the map where the Gs are near 0. So right at the driver reaction time from accel to braking is the key moment on the straight.

 

[logic]

I hate you and your MoTeC goodness and mil-spec cabling.

I see all the usual instrumentation suspects in that sidebar; are you measuring shock activity as well? If so, I'm curious what sensors you're using.

 

[gixxerdrew]

That log is not from my car thats a demo log I dont have tire temp sensors but I'm working on an inexpensive solution for that. I need susp pos data to plot the downforce, so I had to use that log,the other logs I have with susp pos data I cannot post publicly but I wanted to demo the aerodynamics worksheet.

I do use linear potentiometers for suspension movement. Penny and Gilles ones

Even just the MoTeC ECU logs a completely insane amount of data. I have a quite a few sensors on the car which I listed the DAQ inputs used on a previous page. Theres some other sensors as well which I can switch the DAQ connectors to from the default ones. But I can only use 7 analog inputs at a time. With the MoTeC SDL I'll get 8 more inputs off the bat which should do most of what i need i may need one CAN expansion unit if anything.

 

[carfan2000]

what do you mean?

Do you mean what wheels are they?

I bought all of them from wheeldude.com. I'm really impressed, they are very very nice looking wheels.

fronts are
18x10 rota boost, 20 offset
rear:
rota boost 17x8.5 35 offset

This is my favorite thread to date… thanks for keeping us posted on all your progress.

Quick question: I get the advantages of having wider front wheels on your FWD car, but what is the benefit of having a smaller diameter wheel in the back (i.e. 17” vs. the 18” you’re running in the front)?