NC 20BPP Time Attack / Track Car - Build Thread

Postby **orx626** » Wed Nov 18, 2009 10:00 pm

orx626 wrote:Two obvious items that need to be designed and manufactured are the oil filter pedestal and the oil filler neck. The necessity to replace the oil filter pedestal is only an issue on this kit as the supercharger is larger than the supercharger being used on the road-going RX-8 kits.

Hi all, time for a quick update....the oil filter pedestal/block has been designed (refer below solidworks images)and sent out for machining. The block has provision for the the oil supply from the oil cooler and remote filter, an oil temperature sender, an oil pressure sender, and the supercharger oil supply line. It replaces the standard oil filter pedestal shown here.

The custom oil filler neck is currently a WIP

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As mentioned previously, I'm also installing the road version of this kit on my RX-8. Prior to doing this I wanted to check the health of the 13B as it is nearing the 100,000km milestone. There's no point sticking 10 psi in it if it's needing some TLC :wink:

. I recently acquired for work the current special service tool that Australian Mazda Dealers are using to measure rotary engine compression. The fact that there are effectively three combustion chambers being ignited per leading and trailing spark plugs means that a traditional compression testing tool will only measure the highest compression number of the three combustion chambers. The tool is basically a pressure sender that has been calibrated to work in a 0 - 200 psi range and works with datalogging software that you just install on any PC/laptop.

Well after 98,200 km the 13B MSP in my RX-8 yielded the following results (the below graph is for the front rotor):

Front Rotor : 110.9 psi, 109.7 psi & 116.7 psi @ a cranking speed of 216 rpm

Rear Rotor : 110.7 psi, 115.0 psi & 114.9 psi @ a cranking speed of 219 rpm

To put this in perspective, Mazda advises that a brand new 13B MSP should have a standard compression reading of 120 psi at a cranking speed of 250 rpm, and the minimum as 98.6 psi also at 250 rpm. Standard difference in chambers should be within 21.8 psi, and the difference between rotors within 14.5 psi. If your cranking speed during the test is close to 250 rpm, you can use the readings as recorded. However, if engine cranking speed deviates significantly from the Mazda criteria, you may want to proceed with normalisation of the recorded readings. Essentially, slower engine cranking RPM during the test will result in readings lower than the Mazda standard. I haven't normalised the data...but all that's going to show is an increase the compression readings!!! :mrgreen:

In summary, after almost 100,000km the engine is showing excellent health and will respond favourably to a bit of forced induction :twisted:

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Cheers,
Danny

Postby **Okibi** » Wed Nov 18, 2009 10:19 pm

Given the engine is still very healthy, does it drink much oil?

Postby **orx626** » Wed Nov 18, 2009 11:34 pm

Okibi wrote:Given the engine is still very healthy, does it drink much oil?

Hi Dave, I top the oil up with between 500ml and 1l at 3,500km and 7,000km out of the factory 10,000km incremental service interval. It winds up being on or just above the low level mark on the dipstick just before the oil is discarded and a new filter installed at the 10,000km incremental service.

Cheers,
Danny

bruce · Postby **bruce** » Thu Nov 19, 2009 10:54 am

It would have been good to have a compression reading when the motor was new, for comparison.
It drinks a lot of oil, but I've never owned a rotary (I like piston motors to drink zero oil). That is normal consumption?

Postby **orx626** » Thu Nov 19, 2009 11:32 pm

bruce wrote:It would have been good to have a compression reading when the motor was new, for comparison.

Hi Bruce, unfortunately/fortunately I bought the car second hand with 43,000km on the clock. I wouldn't do a compression test when brand spanking new...I would allow the seals to bed in for around 10,000km and then do the test.

bruce wrote:It drinks a lot of oil, but I've never owned a rotary (I like piston motors to drink zero oil). That is normal consumption?

Funnily enough that is one of the 13B-MSP's strong points, as it burns less oil than all previous Mazda rotary engines. So yes, that level of oil consumption is normal.

Cheers,
Danny

SPy vs. SPy · Postby **SPy vs. SPy** » Fri Nov 20, 2009 3:03 am

orx626 wrote: and it caresses itself in oil more often than all previous orx626 Mazda rotary engines
Danny

Pictures = pron
in the flesh = PRON
covered in oil = XXXX PRON
seeing it go around Lakeside = (Okibi deleted this bit, honest he did)

I've seen red motors drink that much Castrol too OR more, though sometimes they had a habit of breaking diffs :shock:

Postby **orx626** » Sat Nov 28, 2009 10:44 pm

I have been chipping away at a few of the jobs over the past week. Firstly, a new oil filler neck came together and then today I got a design for the rear caliper brackets sorted.

A custom oil filler neck is necessary with the supercharger as the standard one is in the way. In addition to this, its a simple option to have the oil from the supercharger return to the sump at this point. Here's the solid model.....

...and here is the almost finished product (sans breather nipple)...this will be positioned once I finalise the engine plumbing.

Back in July I did a trial fitment of a 4-piston Brembo coupled with the same brake rotors as I'm using on the front on the rear end to see if it was doable.

With a bit more angular indexing of the caliper on the rotor I was able to get enough meat between the bolts that mount the bracket to the upright and the bolts that attach the caliper to the caliper bracket. This is the prototype design....Right hand rear assembly shown.

I'm still working towards having the engine to the tuner before Xmas.

Cheers,
Danny

SPy vs. SPy · Postby **SPy vs. SPy** » Sun Nov 29, 2009 12:41 am

yeh good on ya Danny, waste a perfectly good day in the office creating metal pron versus spending all day going sideways.

At least one of us has his priorities straight and I don't believe it's me :mrgreen:

I cannot wait to see this thing eat a track, it will be an awesome day.

Mokesta · Postby **Mokesta** » Mon Nov 30, 2009 6:23 pm

I hope you can bleed those calipers at that rotation. You know all too well from your other car what a PITA it is to have to take the caliper off to bleed it.

Are you going to sell popcorn for all of us who want to come and watch that engine on the dyno? I reckon it'll draw quite a crowd.

M

Postby **orx626** » Mon Nov 30, 2009 10:31 pm

SPy vs. SPy wrote:yeh good on ya Danny, waste a perfectly good day in the office creating metal pron versus spending all day going sideways.

The air-con was sooo good until midday!!!! :mrgreen:

Then I had to go and get tyres stripped, fitted and balanced in the stinkin' heat!!!

Postby **orx626** » Mon Nov 30, 2009 10:34 pm

Mokesta wrote:I hope you can bleed those calipers at that rotation. You know all too well from your other car what a PITA it is to have to take the caliper off to bleed it.

Yeah who would have thought a nipple pointing vertically down and another almost horizontal was the correct orientation!!! :shock:

You live an learn.