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engiekev
engiekev HalfDork
2/22/22 11:49 a.m.

For my purposes a dual TB setup is too much faffing about, I need to KISS and install with throttle at supercharger inlet and get some seat time!  

I also acquired some of the "hollow spoke" NA 14" wheels that are at my coworkers shop getting powdercoated, gloss white of course, and Alpha Eurocross tires are on order.

Kevin Schmidt keeps tempting me with a set of 4.77 rear gears, not helpful! laugh

Kylini
Kylini Dork
2/23/22 4:56 p.m.
engiekev said:

That's really good to know that you can package a 185/65r15, was there any fender liner clearancing required?

If by clearancing, you mean removal of everything plastic in the front, yes :P

Fender liners were definitely removed. This has a side effect of allowing more fresh air (and dirt and salt and water) into the engine bay. This resulted in us actually corroding the headlight harness. xD

P.S.: I endorse electric fans on thicc radiator. It's not like you're gonna move fast enough for natural cooling while spinning those tires!!

Pete. (l33t FS)
Pete. (l33t FS) GRM+ Memberand MegaDork
2/23/22 5:47 p.m.
engiekev said:

For my purposes a dual TB setup is too much faffing about, I need to KISS and install with throttle at supercharger inlet and get some seat time!  

I also acquired some of the "hollow spoke" NA 14" wheels that are at my coworkers shop getting powdercoated, gloss white of course, and Alpha Eurocross tires are on order.

Kevin Schmidt keeps tempting me with a set of 4.77 rear gears, not helpful! laugh

The 4.77s would be crazy in a Miata! They don't rev nearly high enough to take advantage of it.  Every time I think about a 9500rpm BP engine I get smacked down by people who prefer forced induction.

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
2/23/22 6:32 p.m.

Thicc radiator isn't as efficent as cool, as there's more blockage of the airflow and the temperature of the air passing through the back half of the core is already hot so there's very little heat transfer. That's why you don't see them in OE applications. They do work well as a heat sink by holding another couple of liters of coolant, though.

The Miata head doesn't flow well enough to make 9500 rpm worth the investment. I've had a couple of 8000 rpm B6/BP engines.

AnthonyGS (Forum Supporter)
AnthonyGS (Forum Supporter) GRM+ Memberand SuperDork
2/23/22 6:46 p.m.

Remember rallycross is dirty.  I'd be worried about that foam filter in that photo.  And Tein makes a rally coilovers for the Subaru with external reservoirs for bigger fluid volumes.....  They "look" the part, but are they?

engiekev
engiekev HalfDork
2/24/22 8:30 a.m.
AnthonyGS (Forum Supporter) said:

Remember rallycross is dirty.  I'd be worried about that foam filter in that photo.  And Tein makes a rally coilovers for the Subaru with external reservoirs for bigger fluid volumes.....  They "look" the part, but are they?

I hope to make more of an enclosed air box with a UNI filter, and run something like an Outerwears pre-filter if needed, those seem to do well enough on dirt bikes and side by sides.  DDM makes a trick air box, but I will fabricate my own.

https://www.ddmworks.com/1999-2005-Miata-Cold-Air-Intake-for-Jackson-Racing-Superchargers-by-DDMWorks_p_186.html

The M45 kit filter is open element, foam, and sits right by all the exhaust manifold heat.  I hope, with a TrackDogRacing manifold heat blanket, and a sealed airbox, to keep supercharger inlet temps down.  I dont plan to add an intercooler, so keeping the inlet temp down is key.

engiekev
engiekev HalfDork
2/24/22 8:39 a.m.
Kylini said:
engiekev said:

That's really good to know that you can package a 185/65r15, was there any fender liner clearancing required?

If by clearancing, you mean removal of everything plastic in the front, yes :P

Fender liners were definitely removed. This has a side effect of allowing more fresh air (and dirt and salt and water) into the engine bay. This resulted in us actually corroding the headlight harness. xD

P.S.: I endorse electric fans on thicc radiator. It's not like you're gonna move fast enough for natural cooling while spinning those tires!!

Yikes!!  I would really prefer to keep the fender liners but I'm willing to make some sacrifices to the rallycross gods.   Looks like the 185/65r15 indysport BR you ran are 24.96" diameter.

I am in a bit of a tire conundrum right now.  Alpha re-tread tires are the hot ticket right now in detroit region.  Maxxsports or Dmax aren't really available, alternatively stage rally tires MRF are sold by tirestreeets, but I really don't think a stage rally tire is a good choice for this car.

Here are choices (I have both sets of wheels already):

175/70R14 with NA 12 spoke 14inx6 wheels, tire weight=19.84lbs, wheel weight=10.8lbs, total weight=30.64lbs

175/65R15 with NB 5 spoke 15inx6 wheels, tire weight=19.84lbs, wheel weight=13.1lbs, total weight=32.94lbs

Alpha Eurocross comes in these sizes:

No good, too narrow! 165/70R14 - Diameter: 24.02 in, Tread Width: 4.72 in, Tread Depth: 0.55 in, Weight: 17.64 lbs

175/70R14 - Diameter: 24.61 in, Tread Width: 5.51 in, Tread Depth: 0.55 in, Weight: 19.84 lbs

175/65R15 - Diameter: 24.61 in, Tread Width: 5.51 in, Tread Depth: 0.55 in, Weight: 19.84 lbs

No Good, Too wide! 195/65R15 - Diameter: 25.83 in, Tread Width: 6.69 in, Tread Depth: 0.55 in, Weight: 24.25 lbs

https://kcracingstore.com/shop/ols/products/eurocross

¯\_(ツ)_/¯
¯\_(ツ)_/¯ PowerDork
2/24/22 8:46 a.m.

I'd go with the 14s, lighter is better.  I bet some 13" gravel tires would move it right along too, assuming there's a 13" wheel you can fit over the brakes.

moxnix
moxnix Dork
2/24/22 9:59 a.m.

As long as you are not running the sport brakes 13" wheels fit fine. 

engiekev
engiekev HalfDork
2/24/22 10:50 a.m.
moxnix said:

As long as you are not running the sport brakes 13" wheels fit fine. 

I don't have 13in wheels so 14" might be what I go with, 13" means I would have to buy some Braids or others and that's not in the budget right now. I saw an Autozam with these Braid FSAE wheels, that might be funny, they are ridiculously light at 6.6 lbs.

It might have the sport brakes, it's a 1999, it doesnt appear the door card indicates whether it has sport brakes or not? EDIT: it appears no 1999's came with sport brakes.

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
2/24/22 12:57 p.m.

Sport brakes were introduced in 2001, no worries there. This car has the same brakes that were used from 1994-03. You may be interested in an adjustable proportioning valve to adjust for the different grip levels, but otherwise your braking system should be pretty solid if maintained.

engiekev
engiekev HalfDork
2/24/22 6:49 p.m.

Road trip! Leaving for the land of GRM and gators (Florida) in a week. I plan to drive back to Michigan in a two day trip, after our vacation ends. This will be interesting. 

Looking at the route, just north of Atlanta is a good halfway point to crash at Hotel. Any GRM folks in the area?

Lof8 - Andy
Lof8 - Andy GRM+ Memberand SuperDork
2/24/22 7:55 p.m.

In reply to engiekev :

If you have time, take a lil detour through Tail of the Dragon. It was a lot of fun when we did it!

Ando
Ando GRM+ Member
2/25/22 10:42 p.m.

I just installed an old Jackson M45 on my 2002 with a megasquirt and 550cc injectors using the throttle body on the supercharger inlet in the standard manner.  There is no noticeable throttle lag.  I think the crazy dual TB systems are more for the stock computer users.  Throttle lag doesn't make much sense to me as with the original Jackson connector tube you are only adding something on the order of 2 liters of volume to the intake tract.  About as much as the engine draws in two revolutions. 

With the original pulley my M45 would make about 5.5 lbs of boost and on extended runs the intake temps would hit 195 degrees at my humid sea level location.  I was concerned, so I installed the Track Dog intercooler to excellent affect.  Intake temps top out at about 100 degrees now, so I'm thinking of overspeeding the M45 with a smaller pulley to get just a bit more power.  Still no throttle lag, just immediate supercharged torque.  So satisfying compared to a turbo.

As far as injectors go...with kinda rich safe AFRs of 11.5, I hit 68% duty cycle at my low boost level with the 550cc injectors.  I don't know exactly what the OEMs flow at, but you might not have as much room as you hope.

engiekev
engiekev HalfDork
2/26/22 6:16 p.m.
Ando said:

I just installed an old Jackson M45 on my 2002 with a megasquirt and 550cc injectors using the throttle body on the supercharger inlet in the standard manner.  There is no noticeable throttle lag.  I think the crazy dual TB systems are more for the stock computer users.  Throttle lag doesn't make much sense to me as with the original Jackson connector tube you are only adding something on the order of 2 liters of volume to the intake tract.  About as much as the engine draws in two revolutions. 

With the original pulley my M45 would make about 5.5 lbs of boost and on extended runs the intake temps would hit 195 degrees at my humid sea level location.  I was concerned, so I installed the Track Dog intercooler to excellent affect.  Intake temps top out at about 100 degrees now, so I'm thinking of overspeeding the M45 with a smaller pulley to get just a bit more power.  Still no throttle lag, just immediate supercharged torque.  So satisfying compared to a turbo.

As far as injectors go...with kinda rich safe AFRs of 11.5, I hit 68% duty cycle at my low boost level with the 550cc injectors.  I don't know exactly what the OEMs flow at, but you might not have as much room as you hope.

That's some great info! I suspected the OEM injectors will be getting close to 100pct duty cycle with base fuel pressure. Really with megasquirt there's no reason to not go to bigger injectors. I wasn't planning on upgrading injectors unless the data shows the stock injectors are maxing out. As for intercooler and pulley, at least for RallyCross I don't suspect I'll have a power issue. The NA Miata was wheel spinning quite easily with the crappy afpr and OEM ECU setup.

Per Keith:

"1999-00 injectors are 238 cc at the standard 43.5 psi test, 268 cc at 55 psi.

2001-05 injectors are 264 cc at 43.5 psi, 296 cc at 55."

Aren't rx8 injectors cheap, roughly 420cc?

Pete. (l33t FS)
Pete. (l33t FS) GRM+ Memberand MegaDork
2/26/22 6:51 p.m.

As for power, nothing exceeds like excess! smiley

 MSM engine at 10 (?) psi in a lightened '90 (EvanB's car) is an absolute ball to drive, but I also found myself wanting even more midrange torque when the tires were hooking up.  I mean, yeah, it probably doesn't actually give you lower times, but srsly, are we doing it for an 89 cent trophy or an awesome experience?

engiekev
engiekev HalfDork
3/8/22 10:02 a.m.

Picked up the NB without issue, sort of. Allegiant canceled my departure flight after I canceled my return flight, so I was delayed by one day.  Andy was super accommodating and we met up the next day.

I was blown away by his diverse collection, but especially enamored by the gambler smart car, too fun. Andy truly made it a great trip and transaction, GRM at its best!

Loving the car so far, it'll be a great starting point for what I want to use it for.  Megasquirt + Ballenger AFR500 is ready to go at home, and the M42 supercharger will be swapped off the rusty NA soon after I return.

 

Since the weather looked perfect for the rest of the week, we decided to take the top off for cruising around Sanibel.  I found a good deal on a tan soft top I'll pickup on the way home.

engiekev
engiekev HalfDork
3/16/22 7:29 a.m.

The 1400mi drive is done, car did fantastic and averaged roughly 25mpg.  No time this trip to do a run of the dragon, but I did find some nice Georgia and Kentucky back roads, of course the NB feels right at home here and is a revelation.  It almost had me rethinking the plans for rallycross, until I returned to Michigan where any back road with curves is nasty dirt (not all, but 99%).

Plans are underway to swap the supercharger from the swiss cheese donor, with abnormally warm weather here that might happen sooner than anticipated.

No date for the first SCCA rallycross yet, but I'm closely reading the SCCA hill climb rules to see if a run at the Empire Hill Climb is in the cards in the long term.  Quick read suggests the roll bar needs a diagonal bar added (assuming the existing tubing meets spec), seat, harness, and fire suppression.

Pete. (l33t FS)
Pete. (l33t FS) GRM+ Memberand MegaDork
3/16/22 9:29 a.m.

In reply to engiekev :

Depending on your drive motivations, OVR is running at Mid-Ohio a lot this year.

engiekev
engiekev HalfDork
3/16/22 9:51 a.m.
Pete. (l33t FS) said:

In reply to engiekev :

Depending on your drive motivations, OVR is running at Mid-Ohio a lot this year.

Those events are definitely on my radar, not too far of a drive compared to Detroit region and you guys have some really cool venues!

Are the events at mid-ohio mixed surface? Please say yes.

EvanB
EvanB GRM+ Memberand MegaDork
3/16/22 10:16 a.m.
engiekev said:

Are the events at mid-ohio mixed surface? Please say yes.

It's a new venue so unsure what it will be like yet. I would assume most likely not though, unfortunately. 

Pete. (l33t FS)
Pete. (l33t FS) GRM+ Memberand MegaDork
3/16/22 10:28 a.m.

Mixed surface is not permissible at SCCA events, IIRC.  Unless the rule got quietly changed while I was unaware, the surface must be "unimproved" or some such.

They let us launch off of asphalt at Nationals because the timed portion of the course started on dirt.

engiekev
engiekev HalfDork
3/16/22 1:04 p.m.

The detroit region events at Milan were mixed and likely took advantage of the "unimproved" surface, as it most certainly was.  I heard that little section was built by an OEM and then never used, many many years ago.

NER runs Cannan mixed surface as well?

Pete. (l33t FS)
Pete. (l33t FS) GRM+ Memberand MegaDork
3/16/22 2:04 p.m.

In reply to engiekev :

Just because they are doing it doesn't mean they don't risk losing sanction if the wrong people find out.

I thought the Milan events were non SCCA events.

engiekev
engiekev HalfDork
3/16/22 8:19 p.m.
Pete. (l33t FS) said:

In reply to engiekev :

Just because they are doing it doesn't mean they don't risk losing sanction if the wrong people find out.

I thought the Milan events were non SCCA events.

They were SCCA events, I can't say much more than that as I really don't know any more.  Not likely to reoccur with the state of that track, it's in legal disputes.

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