I run mostly in NASA PTD. I use an ecu reflashed by racing beat and have run many exhaust configurations with the same ecu tuning with no apparent problems. I've run with and without header and with and without muffers. Never with a cat on though. Running without the header does seem in decrease the top end performance just slightly. With a header the car will pull pretty well up to nearly 10,000rpm.

 

Do you add a straight pipe out or turndown when you take the muffler off?

 

Yes, I have tailpipe that goes from the rear of the stock location midpipe to the passenger exhaust outlet with a little bit of turndown. Only takes about 10 minutes to switch back to a full muffler when I need to be quiet (I use the racing beat muffler).

 

friend of mine was just at VIR with Grass Roots invitation--he had fastest Mazda there even after loosing his front spoiler. Beautiful track.
For the pro HPDE driver we change ours twice a year. We have been doing that for about 6 years now and its been ok.

 

I have done over 50 track days. Started with standard oil then went to Royalpurple, this caused severe 4th gear grind and turned the oil black. after three flushes with Redline MT90 the problem was resolved. Currently using Redline lightweight shock proof and has perferormed well with two track days in my supercharged RX8.

Stock transmission has been very reliable with 9 yrs of motoring and 107 000km of road and track use. Now that the car is supercharged the load and temperatures and mach greater so I need to look into transmission cooling ideas. Going catless at the track sounds like a good start. Might look into placing a resonator in its place to keep within noise regulations.

 

Lightweight shockproof is certain death in this trans. Shockproof is a race oil not intended for street use. It breaks down under shear and must be replaced often. It is not intended to last 1000 miles, let alone multiple thousands. It is also not recommended for running through a cooler/radiator due to potential fouling.

This transmissions weaknesses and issues are well known in real racing conditions.

 

FYI, from Mazdaspeed motorsports.


General Information
As a rule, differential temperatures should stay below 200° Fahrenheit range. Consistent temperatures above this level can reduce the service life of the limited slip and differential significantly. A new differential and limited-slip unit should be broken in over a period of approximately 200-300 miles. Operating temperatures that slightly exceed 200° F during this period are normal. A 9OW hyoid gear oil should be used for the break-in period. Thereafter, we recommend switching to a synthetic gear lube that is compatible with limited-slip differentials. Torsen-Gleason differentials do not require limited-slip gear oil.

 

Followup:

Happy with the Redline 75W140NS so far (DD and 2 track days since). Haven't had a single grind on the street or track. Removing the CAT had a noticeably positive effect on temperature, as measured from the shifter boot with my hand. Car smells like sh*t though.

The car did not get hard to shift even after running for 60 minutes straight at Gingerman. However, I was only shifting twice (one up, one down) per lap because of brake fade. I would have been shifting 8 times per lap if I could heel-toe.

 

Couple of things wrt to getting a gear oil smell in the car

The top shifter plate has a bonded gasket seal that can wear, come loose, tear, etc. in this instance it can help to replace it, something most people are not apt to do.

There are several rubber gaskets that seal off and isolate the shifter opening in the chassis. It is important to make sure that they are all installed and seated properly.

If gear oil gets on any of the chassis or heat shields it will definitely gas off when hot. It is important to use a solvent or cleaner to wipe down the appropriate areas; around the shifter opening if the shifter is removed, around the trans area after an oil change ...

 

I was referring to the smell from the exhaust. Good advice, nonetheless.

 

Some of it applies for exhaust leaks too, lol.

 

Gentlemen,

So I've got about 70-75k on the trans now with a 3-4 grind on any high rpm <1s street shift and a need to double clutch all 3-2 shifts over ~5000 rpm. I've been running the 75w140ns for that last ~30-35k. My latest batch has three track days (~400miles) and ~5k street miles. My plan was to try some fresh 75w140ns but I'm open to recommendations if that doesn't work. I have some extra lightweight shockproof I was going to try in a 50/50 mix but I'm not sure if I should try some MT90 instead. Is there any reason to believe the MT90 would give better high rpm performance than the 75w140ns?

I have a lower mile S1 trans with a bad throwout in the garage but I'm thinking it might be a better plan to sell it and swing for a used s2 trans. I probably wouldn't get to swapping the transs until the winter as I'm only looking at 4-5 more track days this year. Tires and brakes take all the $$!

Thanks

 

S2 trans holds up better so I'd recommend the swap. This is not to say you can't break the S2 trans as well... I would know...

 

Lol, getting the thread back on topic I've been using the Ford Motorcraft XT-M5-QS 75W90 GL4 synthetic trans oil with good results for the last 2 years. Not cheap though, local dealer gives me a break at $18/qt ...

 

Update:

Put the spare transmission (~40K) in last week with some fresh MT90. Swap only took ~3hrs with a couple friends and beers. Shifts like butter. Better than the other transmission ever was. I'm guessing the old one was faulty from the beginning. Track test to come in a few weeks. I just have to resist doing super quick shifts now that the trans can do it.

 

I would strongly recommend the Motorcraft oil instead ...

 

I've heard good things about the Motorcraft and will give it a try if the Redline oil does not work on the track. Dave @ Redline also suggested I stick with an 75w90 and that benefits from heavier fluid are rare and can be indicative of the transmission already being damaged.

 

The Motorcraft XT-M5-QS fluid is a GL-4 75W90

I never cared much for MT90, especially before it warms up

 

I actually find the MT90 much smoother on the track. But yes, more notchy on the street and in everyday use.