MADJAK's NA8 - 200+HP N/A

Postby **beavis** » Wed Jan 11, 2017 9:51 pm

Was going to email you, but thought it might be better for everyone if i ask my question here...

Whats the latest news with the gearbox?
Any progress with the guard vents?

madjak · Postby **madjak** » Thu Jan 12, 2017 2:56 am

I'm still waiting for the dogs to be machined and cleaned up a bit. I have been playing around with a design to make a sequential shifter for an MX5 box though.

The guard vents haven't had any more work due to the above! I'll get back onto them soon.

StanTheMan · Postby **StanTheMan** » Thu Jan 12, 2017 6:06 am

Sequenchal mechanical shifting .

I recon that would be a bucket load of fun.

madjak · Postby **madjak** » Thu Jan 12, 2017 12:36 pm

Yeah... I'm going to build it for my box but it could work on a standard 6 speed too. You'd still need to use the clutch but would be fun.

madjak · Postby **madjak** » Sat Jan 14, 2017 3:07 pm

I'm pulling out the engine to check bearings etc. Guards and slicks are on but still need painting. The autokonection flares fit well but there is a fair amount of metalwork involved.

The track width of the car is nearly 4" wider now.

madjak · Postby **madjak** » Sat Jan 14, 2017 7:02 pm

2 hours... engine is out. I'll pull it down, check and replace bearings, rings and reset valve clearance. This engine has probably done only 6 hours of work since the last engine rebuild 14 months ago but is actually overdue for a rebuild.

madjak · Postby **madjak** » Tue Jan 17, 2017 5:14 pm

It looks like it's a bit of a bigger project than just a simple refresh!

The big issue is the valves which must have been getting some valve float. 4 of the intakes and 3 of the exhaust valves have been pounded up into the head which is why my lifter tolerances have reduced. Not only that but there is some damage on the lifter tops on a couple of the lifters so I'm going to need to source some new valves, new lifters and rework the head!

The good side is that the bottom end looks awesome, with the bearings in great condition. This tells me that the sump baffle and the penrite 10 tenths oil is working well and have stopped the oil starvation issue I was seeing. So thankfully I don't have to touch that.

Now I've got less than 4 weeks until the first event so it will be a bit of a challenge to get it all together before then, especially given there are so many odd bits required for this head.

Postby **Okibi** » Wed Jan 18, 2017 1:27 am

Fingers crossed you can get the bits you need.

pepejesus · Postby **pepejesus** » Tue Feb 14, 2017 12:43 pm

http://www.miataturbo.net/race-prep-75/wider-23-hoosier-a7-92163/

For when you get the Rotrex going... :twisted:

madjak · Postby **madjak** » Tue Feb 14, 2017 1:02 pm

Wow... I thought the 245 Hoosiers were big!

Postby **beavis** » Tue Feb 14, 2017 7:23 pm

RIP bearings etc.

pepejesus · Postby **pepejesus** » Tue Feb 14, 2017 7:27 pm

Work happening on that front too, these things look like they're not far off: http://www.miataturbo.net/race-prep-75/tapered-roller-bearing-hubs-its-happening-88149/

ianoz · Postby **ianoz** » Wed Aug 23, 2017 1:45 pm

what's your long-term view on the suspension bush bearings you machined up back on page 5? Worthwhile compared to regular greasing of standard poly's?

I have access to lathe/mill etc (and someone who doesn't have 5 thumbs on each hand like me..) but keen on real-world experience whether it's worth the work for a club day toy that only turns a wheel a few times a year.

3gress · Postby **3gress** » Sat Aug 26, 2017 4:18 pm

Updates on dual feed reverse flow coolant setup?
When you get time between all those outside the box projects that keep the rest of us humble of course!

madjak · Postby **madjak** » Fri Sep 29, 2017 7:37 pm

3gress wrote:Updates on dual feed reverse flow coolant setup?
When you get time between all those outside the box projects that keep the rest of us humble of course!

Between work and kids I don't get a lot of time to work on things at the moment! I also find winter slows me down a bit.

My sequential pneumatic shifter is almost ready to bolt into the car, but I have so much to tweak on it still. It's been a mamoth task getting not only the mechanics right, but also learning pneumatic control and doing all the coding on the arduino. Once I have something a bit more solid I'll create a post for it on the forum. This is a quick video showing the arduino controlling 7 pneumatic valves for the shifter. So a set of 3 valves for each 3-position solenoids (2 x extension, 1 x retraction) and 1 for clutch.

I also have shiftcut output to ECU, CANbus RPM, TPS, MAP input, clutch pedal input and an array of magnetic sensors to test for achieved gear and display that to a LED. I still need to add autoblip control and then integrate it all into the code. I've tested the pneumatics on the gearbox at full air pressure and the shift can be so fast it sounds like a single clunk... probably around 30ms or so. even the 2nd to 3rd shift where it has to move up then across a gate then up again. These pneumatics are powerful so I'm being extremely careful to not do things wrong which might bend a shift fork or break things.

My current issue I'm working through is figuring out how to shift into 1st and Reverse from Neutral when the car is stationary. My concern is if I shift without the input shaft moving that the dogs might hit on the tops of the gears rather than mesh. I think there is a good reason why WRC cars jump forwards or backwards when engaging the first gear... it's because the clutch is only 90% engaged so that the gear box is spinning. Maybe I can do something similar by adjusting the clutch point out.

The reverse flow coolant setup it works brilliantly. I really don't think or worry about it now because it just does it's thing. My engine ran cool all through the summer events, not that it got that hot previously, but the logs show it sitting right at 85-88 degrees flat exactly where my PWM map ramps up. It comes up to temp quickly during idle and cools down quickly when I pull into the pits if I leave the master kill switch on. Considering my setup is a bit unique, it would need to be checked again on a stock engine but overall it's been one of my favorite modifications. The engine just wants to rev now and feels like it has picked up power... especially over 7000rpm.

I've upped my rev limiter now to 9000 and it pulls all the way! The engine is epic combined with the close ratio dog box. Gear drop from 8800 3rd to 4th is only 1380 rpm and from 4th to 5th it's a tiny 1100rpm so they are super close. This is why I need paddle shift as I'm having to row through the gears even on the short straights!