Rally BRZ v2: Open 2wd Boogaloo

Remove stuff, clean stuff, remove stuff, clean stuff, remove stuff, clean stuff...

The wing is giving off supra vibes

In reply to RustBucketLegacy :

You mean Subra, right?

¯\_(ツ)_/¯ said:

In reply to Shavarsh :

Not a clue!  I know they can make over 300whp in transverse applications, and I'd be very happy with anywhere near that- the L2wd car's FA20 is probably putting a whopping ~165hp to the ground so it'd be a massive upgrade.

Speaking of which, I just sold the FA20 from this black car, which has basically zeroed it out by Challenge math.  Motor mount parts have been ordered and much removal of stuff from the shell is ongoing.

The general rule I have seen is that 300hp is about as much as you can realistically put down with 2wd on gravel, and that's why ex-German E36 M3s were so popular in Finland.  (They'd fail the German road inspection, I guess, and could be had for $cheap as long as they left Germany)  They already made enough power, so that could be left alone.

A 2GR in a BRZ will be nuts.

In reply to RustBucketLegacy :

It may be a Supra vibe, but it needs to work at a far lower speed than that bitty thing.

¯\_(ツ)_/¯ said:

In reply to irish44j (Forum Supporter) :

I really, REALLY looked hard at a number of interesting older cars- mid 80s Toyota products mainly, even to the point of going and checking out a few KE70 Corollas and doing a pretty detailed measuring session on my 85 MR2.  Ultimately, as much as I'd love to build something with that much cool factor, and as much as the lighter weight might make it better on paper, I decided that what I really want out of this next car is to compete with it, a lot; 40 year old cars are still 40 years old, and come with parts sourcing problems and additional work because of it. A modern shell with modern components and a super healthy supply of good used parts should mean I can run more events and therefore get more practice and be faster.

I love old rally cars but I don't see very many of them showing up to 6+ events a year, and that's my plan so here we are.

A guy I crewed for picked up a first gen RWD Celica for a stage rally project, we drove it around as a street car while sorting the mechanicals, and it had some hopped up 2Tsomething motor.  It ripped, and on paper seemed seemed like the ideal choice....   But the second you sat in that thing, you became acutely aware of how little 'car' was between the driver and the outside.

In a sport where you may become acquainted with with the greenery, it's nice to have something modern around you if you're going fast.

Looking forward to following this build!

In reply to rallyxPOS13 :

Just for funsies, and because Americans will use anything but the Metric system, a Stratos is mid engined with a transverse V6 yet has a wheelbase 3 inches shorter than an NA Miata.  The darling of rear drive rally, the Ford Escrot, is four inches narrower than a Miata.

The first gen Celica had roughly the same wheelbase but was an inch wider than the Ford.

Think of that when you see guys winging those old Mk1s and Mk2s around the forests.

A BR-Z by contrast is a very long, wide car 

There was a version of the Aisin AZ6 which mates to GR engines. It was used in the Lexus IS. I'm sure some casting swaps would make it all bolt in.

In reply to burdickjp :

The starter is the bugaboo, no? Front drive and rear drive engines had the starter in different places.  It looks like the bellhousings are kinda different.

The AZ6 is kind of interesting in that they aren't standardized.  The MX-5 and RX-8 both used versions of the AZ6 and they share practically nothing.  All of the bearings are of different sizes, so one can't just swap housings from one to the other.  One would have to get a BRZ and IS250 transmission, take them apart, and get measurey, before assuming that they are the same internally.  Or find parts lists and start cross referencing.

...now I wonder if the RX-8 trans I have is in any way compatible with BRZ stuff.

I've conducted this experiment- end result was minimal compatibility, and I sold the IS250 transmission. It seemed like a slam dunk on paper but the housings share almost nothing, and I can buy a dozen BRZ transmissions for the cost of a single IS250 one.

Pete. (l33t FS) said:

A BR-Z by contrast is a very long, wide car 

And the USA has, by contrast, very fast, wide roads- I wouldn't mind something a bit smaller but the cage and halo seats shrink an interior in a hurry!

Just saw your post in the FB MP group selling OEM interior and assorted parts, I was like "ok what's he up to now?"  Admit I haven't kept up lately, here's me following along now.

BTW - those seats heated by any chance? 

In reply to Jerry :

They are not, sorry!

Y

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Lots more stuff removed this weekend- this is the "keep" pile:

Engine bay gutting will continue once I get the harness out:

I got proper windshield removal wire stuff this time, and it was still awful- I think there's just no pleasant way to remove glass:

I will say though, for getting the sound deadening tar up off the floor- this vibratey saw thing with the scraper blade works AWESOME:

This chassis doesn't have much of it, but what's there is really heavy for how compact it is- this is one side:

Getting there!

In reply to ¯\_(ツ)_/¯ :

I made a thing once, and thankfully I have thrown it away.  It was an old dull recip saw blade that I used a flap wheel to put a nice sharp edge on it instead of teeth.  I made it for removing the glued in rear window from something or other.

I also have, somewhere, a thin flat flexible "trim removal" bit with a .401 shank for an air hammer.  That looks a lot like what the actual glass companies use to cut the adhesive.

¯\_(ツ)_/¯ said:

Aero and Bodywork
The hood is probably going to need at least some alteration to fit a tall v6 under it, and I might as well look at making the trunk and maybe some other stuff lighter while I'm at it.

I also think a wing would help at higher speeds, so probably worth doing one of those as well.  I've got something drawn up with the MSHD airfoil profile and a general support concept that attaches to the rear quarter so that the trunklid can become a floppy nothing, but not much else in that department right now:

Looks like you started this thread while is deep into the sleep-deprived stage of OneLap this year.

I'll note that none of the publicly available MSHD foil coordinates return "as predicted peformance" per the original design paper when I've pulled them into Xfoil and analyzed them with the same setup conditions.  Is there a particular reason you think you need that foil?  I recall there was some question of "how much front downforce can I make with these rules?" in the past.

also... there's some aspects of the upright design that I'd probably suggest doing differently.

In reply to sleepyhead the buffalo :

Just seemed to be a solid choice based on numbers- anything that works at lowish speeds is fine, this car will spend a lot of time in the 40-80mph range and doesn't need to go faster than about 120mph.

I'm open to whatever for endplates, but would prefer that they support the wing since having extra wing hanging out to the side is a great way to accidentally grab foliage. 

In reply to sleepyhead the buffalo :

And since I know we'll end up there eventually, here's the wing snippet from the ARA rules:

Dash bar removed- even with no windshield, an unpleasant job:

Right now I'm thinking that I'll probably chop the portions that hold the steering column and electric power assist out, and weld them to the dash bar on the cage later.  I think I see a reasonable spot to graft in a quickener just after the EPAS motor and still keep the collapsible section, which I very much wish to retain.

I don't know if I missed this, but do you have a targeted timeline to completion/shakedown?  

Following along intently!  You're making good progress it seems! 

In reply to golfduke :

I have ideas for when I'd like things done, but realistically it's more important to do the best job I reasonably can than to have the car ready to rally by a specific date- I am still learning plenty driving the L2wd car.  So, no official deadlines.

¯\_(ツ)_/¯ said:

In reply to sleepyhead the buffalo :

And since I know we'll end up there eventually, here's the wing snippet from the ARA rules:

yes, we will end up there.

reading those, there's one potential grey area I see already, maybe: those rules don't obviously preclude having a spoiler on the trunk and a wing above it?  or, would the rule of "only one rear wing is permitted with one main horizontal profile" be the limiter there?

so, as I understand it, the plain english is: wing has to be within the planform of the vehicle body (both by rules, and by "don't snag stuff" imperative)... which is part of what's driving the limited span and setback.  but, "area unlimited"... and no "moveable surfaces, when the car is in motion".

one issue with the uprights being flat on the inside is that it's going to cause an "intersection drag" slow down where the foil meets the upright.  it'll cause disrupted flow from about the lowest point, and spread across the span at a ~30deg angle (based on flow visualization I've done on 9LR wings).  as it happens, something like the supra wing would actually alleviate this issue (think of it as similar to the radiused panel between the lower wings and bodies of WW2 aircraft).

can you give me a rough chord and span length for that wing; and distance to the nominal/expected CG?

In reply to sleepyhead the buffalo :

You can totally have a spoiler on the trunk, so far at least- I see several out there on O4wd cars with wings above them.

Span as-drawn is 50" and chord is a probably-excessive 12".  Distance to hopeful CG is going to be in the 65-70" ballpark from center of wing.  Opposite end will have hood vents and maybe some attempt to get the wheel wells to not generate lift but otherwise very little aero work.

Of note compared to your usual aero stuffs- this will be quite sideways, regularly, as well as flying and pitching up/down accordingly.  I honestly want it in part just to get the thing not to nose down off jumps.

The fabricator wants to know if the flow disruption can be mitigated by making the span taper smaller to the rear, without the complex curves of the hoop wing on a Supra. Such a taper will only improve airborn directional stability if the sideplates absorb all of the taper so that their outer surface remains parallel to the center line. I don't remember where I saw an example of that, but it is not an original idea.