Time Attack BRZ

[wrxracer519]

this looks so good. Great work so far. Can't wait to see the next update. You are building a very cool, fun car.

* Registered users of the site do not see these ads.

[Norm Peterson]

Can hardly wait for a track session video with overlaid datalogging . . . yeah, I expect there will be a bit of 'sorting' involved.


Norm

[JDwhiteWRX]

Setting up the suspension is a big concern for me but it should come together eventually. I won't buy rear coilovers or build the front bellcranks until I know my corner weights though.

I'm really glad I made the inner control arm mounting points so adjustable, I've already moved the top inner mounts down a little to add some camber gain but I can see the lower mounts will probably need to be slid down a little too. I've got to measure everything again at some point and adjust it all to my original model I came up with in the software.

[JDwhiteWRX]

I have been working on the front end, trying to make the panels fit over the new wheels by trimming away metal and plastic from the front fenders and bumper.

This photo shows how low the car is and also that I have extended the wheelbase by 35mm by moving the front wheels forward.

//i.imgur.com/VBtOB2v.jpg?1

After some trimming I could get the panels back on, you can see I need to remake the panels with a new shape.

//i.imgur.com/9pl4dXn.jpg?1

//i.imgur.com/3NS5dnU.jpg?1

I also had to seek some clarification on the rules as one section said I could cut away any metal necessary for bump clearance and another section said I could only make changes to the shock towers solely for suspension geometry changes.

After getting the go-ahead from the technical director I did the minimum amount of trimming to the strut towers so the tyres would no longer make contact.

//i.imgur.com/v3rpJ0v.jpg?1

//i.imgur.com/taJECoK.jpg?1

I have also been trimming away some metal around the wheel wells to help with air evacuation, I post some photos of that once its done.

[JDwhiteWRX]

Looks like I have found a workaround for this strange thing that has been happening with my photos.

For some reason it kept going to some website http://dereferer.org/

[JDwhiteWRX]

I've been in lockdown the past few weeks and it probably won't end any time soon. Luckily this has given me plenty of extra time working on the car.

Most of the work has been around getting all the front end panels mounted onto the car. I bought some 16mm x 1.2mm 4130 chromoly tube and a very cheap manual bender from ebay. The bender snapped during the first bend but I was able to modify it to mount in my vice and now it works surprisingly well.

The tube structure I'm building is very light and will be removable by taking out several bolts. First step was to make a rear mount on the chassis.

//i.imgur.com/UOqCYKa.jpg?1

This is how all that turned out, one on each side.

//i.imgur.com/yOgUiKk.jpg?1

Then it was just a matter of bending some tube and making some tabs to hold the fenders in place.

//i.imgur.com/O21jXLg.jpg?1

The whole thing is rather basic but it is surprisingly sturdy.

//i.imgur.com/7eHaKu7.jpg?1

This is it after finishing both fender mounts. More tube which I have already bent up will continue around the front and attach to the top of the bumper. I have left that bit off for now and started work on the main reinforcements to the front chassis rails.

//i.imgur.com/MK26pXy.jpg?1

[JDwhiteWRX]

This is my proposed tube routing to reinforce the front frame rails. Lots of measuring and clearance checks to arrive at this point.
What do you guys think?

https://www.instagram.com/p/CRdWRYCHCkW/

[Homemade WRX]

Looking really good now! I also didn't know you had an instagram. Following you now.

The front wheels being moved forward screams to have some proper pieces made to help get air out of the wheel wells!

-Micah

[JDwhiteWRX]

I was playing around with the bodywork today, nothing serious, just kicking around some ideas.

[speedyHAM]

Vents on the rear side of the fenders will help a great deal with evacuating air from the wheel wells.

[Homemade WRX]

I was thinking vents more like a 911 GT1 or the WRC style that roll into the wheel well itself.
The vanes like on the JGTC BRZ would be tricky copy in composite (for me) and a lot of CFD to optimally aim. Don't forget they also carry off the back of the fender like a shelf towards the mirror.

[JDwhiteWRX]

I intend to leave the back of the fender completely open, I just made the mdf run all the way down so it sits level.

[JDwhiteWRX]

Work has begun on bringing the strength back into the front end, much more to come.

https://www.instagram.com/p/CRs-gwPH...dium=copy_link

[Homemade WRX]

Yeah, saw that on my feed. Just as satisfying to see it again

[wrxracer519]

wow, I can agree, that is very satisfying to see. Great work. How do we coerce you to work faster

[JDwhiteWRX]

Here is a little update on the work I'm doing to stiffen up the front end, it's really coming together now!

//i.imgur.com/mSVDYSr.jpg?1

What I've done is bring tubes from the roll cage into the engine bay in a triangulated 3d structure that should prevent flex in any direction.

//i.imgur.com/2VV7qNI.jpg?1

You can see the tubes are coming from the top and bottom of the A-pillar and then coming back to an additional mounting point in the center of the transmission tunnel.

//i.imgur.com/TPF76W6.jpg?1

//i.imgur.com/LA1UeRe.jpg?1

close up of the notched junction

//i.imgur.com/OtxxhBc.jpg?1

//i.imgur.com/8C4UOCb.jpg?2

There will be another brace across the front of the engine but first I am going to take the engine back out and weld everything I've done so far. I also need to make a bracket and mount the dry sump oil pump to the engine to make sure there will be no clearance issues with the brace at the front.

[JDwhiteWRX]

New video showing the progress with the front end

https://www.instagram.com/p/CSGkeSdH6E0/

[JDwhiteWRX]

Lots of work has been happening but I've had trouble getting the photos to upload to Imgur off my phone so this update is a bit overdue.

The final pieces in the puzzle went in to the front end. These short lengths of tube join the new structure to the frame rails.

//i.imgur.com/xhgfbVs.jpg?1

//i.imgur.com/Q8BCcES.jpg?1

//i.imgur.com/8HdZ8Cr.jpg?1

With that work done I needed to get my dry sump oil pump mounted onto the engine so that I could finish the bracing across the engine bay without any potential clearance issues.

If you recall I bought the dry sump not as a kit so I have had to fabricate my own oil pan and mounting bracket for the oil pump, this saves lots of money.

I started with a piece of scrap 6mm steel plate.

//i.imgur.com/wTWOxiX.jpg?1

The alignment of the oil pump to the crank pulley is critical and there is a specific distance between the pulleys.

//i.imgur.com/jXcBUiE.jpg

I used different clamps to the one in the photo above, a large square and lots of measuring before getting the final position. Once I was happy I used transfer punches to mark the holes out for drilling.

//i.imgur.com/SapQGoc.jpg?1

The final product had some attempt to reduce weight with a step drill and carbide burs.

//i.imgur.com/lNVB27u.jpg?1

The end result was spot on. Below you can see me test fitting some of my accessories before returning the engine to the car.

Of special note is the starter motor which was specifically designed for the Honda K-series by Carwood Brise. Compared to the OEM starter it is twice as powerful, 25% lighter and more compact. As an added bonus I was able to mount it with my BMW ZF320 5-speed without modification to the transmission as this starter runs a twin nose bearing design which means there is no large snout over the cog that would normally foul on a RWD trans configuration.

https://brise.co.uk/honda-k-series.html

//i.imgur.com/POFudj6.jpg?1

I got the engine back into the car and everything fits perfect, no clearance issues.

//i.imgur.com/iqE38no.jpg?2

The steering rack is close but that's how I designed it.

//i.imgur.com/AiSshfY.jpg?1

So that's where I'm up to for now.

My electric water pump arrived yesterday so I will be looking at places to mount that. I am going to start building the final brace across the engine bay which incorporates extra bracing for the steering rack.

I still need to order a turbo but I'm having trouble deciding which one to get. Turbo and steering column/shaft are the next two things that need to be ticked off as they both occupy the same space. Also the radiator/intercooler needs doing.

//i.imgur.com/aO3GjLr.jpg?1

[Homemade WRX]

So continuing our discussion from yesterday and adding some content here.

Here is your 9174/9180 compressor map

Here is an overlay of the 8374 and 8474 compressor maps.


You can clearly see the 8474 made a huge mass flow gain over the 8374 and jumps to mass flow ranges of the 91xx compressor, albeit, lower efficiency.

Now here's the 9180 and 9280 overlay. Again, not the large jump in mass flow but drop in efficiency. No doubt worth the trade off.



Being a K24A2, making some shorter exhaust manifold for responsiveness over peak power, I think the larger frame turbo would grow on you for sure and leave you room for some 'unlimited' class power. You could simply run it at the low boost for shake down, get used to the lag, dial in ALS, etc...

I do think a DCT/8HP70 would make it FAR easier to pilot and keep lag and recovery time from each shift to an absolute minimum. They do come with some weight and heat penalties though.

Sticking with that old 5 speed, you might be better off with the mid-size frame of the 8474 and knowing you've left time and power on the table which you can always address later.

[JDwhiteWRX]

Thanks for this info mate, the DCT is never going to happen, I'd purchase a real sequential before I'd ever purchase a DCT for this car.

Did you find anything on the 9174? I have looked through some comments from Geoff at Full Race and will summarise below:

• 9174 behaves similarly to 8474

• Fred Aasbo (papadakis racing drift team) ran 8474 vs 9174 back to back on the same track and could not tell any difference. Their data shows 50-150rpm later spool but the tune did not change and he still uses 8374 for the smaller track Formula Drift competition

• On 4/1/2021 at 1:19 PM, Robo said:
  I went from a 7163 to 8374 to 8474 to 9174 and I am glad I did, it's an incredible turbo with amazing spool.
  
  Geoff: I'm glad to hear you like the decade old 9174. it remains a relevant turbo and due to a price discrepancy (that was never resolved) 9174 is the lowest cost EFR in the lineup. a bargain compared to almost anything else in the same price range

Link to all these comments here
https://www.sau.com.au/forums/topic/...v-20/page/131/

As I mentioned in our messages, there is a significant price advantage with the 9174 as also mentioned by Geoff's comments. The AUD is really weak against the USD right now so the price is important.

[Homemade WRX]

I had not realized that the 9174 was about $150 cheaper than the 9180, which is about $150 cheaper than the 9280.

And as for DCT, I get it. I mean I too would go with a real sequential if money wasn't a factor.

[JDwhiteWRX]

I'll just leave this here...

[JDwhiteWRX]

ok one more photo

[whozatguy]

Awesome! This is great to follow.

[wrxracer519]

yes, yes, and more yes! That looks amazing