TeamRX8

iTrader: (25)

yeah, pretty amazing how much it can dance around.
.

John V

iTrader: (1)

There is a provision for mounting an idler in the middle of that span, I may need to turn a custom pulley to use it. My belt routing is the factory setup for a Mazda3, but they don't rev past 6,500 RPM in stock form.

TeamRX8

iTrader: (25)

That might be a good idea. Hard to be sure if the belt would ever come off or not, but might be better safe than sorry. The first time I ever saw a high speed camera video of a self-tensioning belt pulley it made me appreciate not having one. The flip side of course is it’s fairly easy to over tighten a manually tensioned belt and take out the main bearing.

billyboy

If it's the point in the front cover I'm thinking of, doesn't appear to be much meat for a tensioner....hard to remember exactly now, with a lot of bosses machined off the covers here though. My understanding, there's a harmonic in all these spring loaded ones, no matter the vehicle and all the engine builders locally discard them for anything competition related.

I remember one of the UK based Duratec/MZR specialists was selling a manual version for something stupid price wise. Something as basic as a mount and an eccentric pulley you wouldn't imagine could cost several hundred quid, let alone dollars!

John V

iTrader: (1)

The center boss on the front cover is used for an idler in more than one stock MZR / Duratec configuration. The Mazdaspeed 3 I have out in the garage has an idler there

Laminar

This is an awesome build, really inspiring work. What did you end up going with for a limited slip?

John V

iTrader: (1)

Thanks for the comment. The rear end currently has an Eaton Trutrac, which is a helical gear-type LSD.

Laminar

Another question - how do you determine your ideal rear end ratio? Do you aim for max anticipated course speed at redline in 2nd gear and back-calculate the ideal rear end from there?

John V

iTrader: (1)

Essentially yes.

TeamRX8

iTrader: (25)

this was before he changed the transmission and revised the gear ratio for it.

I recall that the new set up has a 1.73 2nd gear and 4.30 rear gear on a 315/30-18 Hoosier (25.6” OD). That works out close to the same.
.

John V

iTrader: (1)

That's right.

I'm turning the engine to 7,500 regularly now that it has better bearings and rods and that works out to around 75 at the top of second, and it can go up to 8k if needed. But I also got no-lift-shifting working so gearchanges don't hurt nearly as much.

TeamRX8

iTrader: (25)

must be pretty awesome, congrats on everything you’ve accomplished to date, and will accomplish in the future

John V

iTrader: (1)

My rustiness shows in this vid from the past weekend's SCCA Champ tour in New Jersey, but the car is just fantastic. Great competition against the car that has won more Street Mod national championships than any other, with a (three?) time jacket winner at the wheel. I finished behind him by a decent amount despite leading by 0.2xx after Saturday (which was super rainy). Looking at his data versus mine, it all looks like poor driving on my part.

Laminar

Nice! That looks like a really bumpy lot - still running 750/500?

Also I've never seen the barcode scanner before, we just punch car numbers into the timing computer by hand like cavemen.

John V

iTrader: (1)

1000/700. Yes, the lot is basically built on a swamp, so it's littered with low-frequency bumps.

The scanners have been used at National level events since around 2009. As someone who regularly works timing, I'm actually not a fan of them.

TeamRX8

iTrader: (25)

a larger diameter steering wheel might help dampen the inputs some

John V

iTrader: (1)

I don't know what you're getting at.

TeamRX8

iTrader: (25)

it’s just an observation from watching the video

John V

iTrader: (1)

Okay, but I don't know what you mean.

John V

iTrader: (1)

Pretty happy with how the car performed at Spring Nationals. I took the SM win at the first tour and Sam took 2nd in SSM. I finished second at the second tour (fastest time second day) in SM and Sam was again 2nd in SSM despite being screwed on day 1 as an only driver on a drying course. I was 7th on index and 4th on index at the events respectively. Sam would have been 1st (by a lot) at the first one had he been in SM. The car definitely needs a clutch diff. We struggled with the TrueTrac spinning up an inside tire.

I haven't bothered to do my videos yet but here are Sam's.

Here's his best from Friday (day one of the first Tour): Here's his 2nd best from Saturday. Camera died for his final run which was a bit quicker: Here's his best from the second day of the second tour. First day was raining:

Laminar

Great driving! Are you thinking a Ford factory-style LSD just built with specific clutches? Or something else?

John V

iTrader: (1)

I ordered an OSG

TeamRX8

iTrader: (25)

good choice and congrats.

John V

iTrader: (1)

Thanks, but it looks like it'll be 2022 before I receive it

TeamRX8

iTrader: (25)

huh, was just looking at it on the OSG-USA website about a week ago for the 8.8 Ford and thought it was in stock

edit; maybe my recollection is incorrect, was looking at several different applications