Trav’s Race Build: from B6 to Big Bore BP-Z3

[Scoota]

Hi Tim.

I take it all back... ITB plenums for BP engines are not uncommon. If I’m honest, I hadn’t gone searching the internetz, so I spoke too soon. There are dozens of different designs out there.

Thanks so much for the link to that forum topic. I read through it all last night, and I am pretty excited about the prospect of unlocking mid-range torque via longer trumpets, and generally more horsepower via clean cold air. Magpie and his supporters sure have done some valuable investigative work in this space, so I’ll definitely be referring to their findings to guide my build.

Now that I’ve seen the magical Magpie air box I am having trouble unseeing it. There are so many aspects of the design that appeal to me. It is likely that mine will adopt a few of the key features.

How much horsepower am I expecting from this engine? More than I have right now. I know it has lots more potential. How much do I want?? 200rwhp!!!


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[Scoota]

...and how many torques do I want?
Well, all of them, obviously.

Honestly though, I don’t really know. I’m just trying to make good decisions, and I’m hoping that the horsepower (and drivability!)
that lies within is unlocked with each good decision. Camshafts, for example. The cold air intake is another example.


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[Scoota]

Challenge Bathurst 2022.png

My kids have requested a trip to Bathurst to play mini golf and play on the jumping pillow at the caravan park. Our trip is likely to coincide with 2022 Challenge Bathurst. Who am I to refuse?! ;)

[Scoota]

I haven't done any racing since July 2020, and the car hasn't been touched since then. With the announcement of the 2022 dates for Challenge Bathurst I am now a bit excited about getting back to the track this year, with a view to having the bulk of the car's issues sorted well before November. You can read back through this topic to get up to speed on where I got to with this build, but here's a summary...

* I have a heavily modified head, but I had to fit standard BP-Z3 camshafts (race day deadline), so the engine's output potential is somewhat nobbled.
* I have Silvertop ITBs with a PiperCross filter, ingesting hot air from the engine bay (no air box).
* I still have a signal earth issue causing "noise" in the system (eg. unstable/noisy TPS signal).
* I have no Idle Control Valve (ICV).
* My battery is knackered. A slick LiFe solution is required.
* The "cold side" of my engine is very congested, so a "hot side" coolant reroute is on the cards. This will make room for the ICV and airbox/intake.
* My trailer has been stripped and needs new springs/hangers, new wiring, new ramps, and a paint job.

I am super pumped to announce that.... I HAVE ORDERED NEW CAMSHAFTS!!

I have chosen CAT Cams 3702606 jobbies: http://www.catcams.com/portals/0/pnplot_files/3702606.png

I'm excited to be back in the shed working on this beast, and I'm looking forward to sharing the story. I've already started on the coolant reroute, and I have a rough plan for the ICV install. Here's a reminder of what she looks like...

Race Car.jpg

[Scoota]

As I mentioned last week, I need to open up some space on the cold side of my engine bay. The current nest of ITBs, vacuum lines, sensor cables and coolant pipes is just a mess. It came together pretty hastily and it works, but it's far from ideal. I need to tidy it up to make space for important stuff like the Idle Control Valve and the cold air intake box. Here is what it looks like currently...

Cold Side

IMG_0140.jpg

Hot Side

IMG_0132.jpg

As you can see, not the neatest engine bay. You can barely see the whiz-bang throttles and manifold, which is just not cool, considering the time and effort that went into making and fitting them. ;)

I have decided to start with the coolant reroute. The coolant return to the radiator needs to come via the hot side. I've made a start on the brackets that will support the 32mm aluminium tube that will run from right to left across the top of the radiator. Can you guess which YouTube channel I have been watching for inspiration?

Coolant Reroute 1.jpg

Coolant Reroute 2.jpg

Coolant Reroute 3.jpg

[Scoota]

More pics of the coolant reroute brackets so far...

Coolant Reroute 4.jpg

Coolant Reroute 5.jpg

Coolant Reroute 6.jpg

I'll need two of these brackets to support this length of aluminium tube, hence the second one (rough cut) in the picture. I didn't quite get around to folding them tonight. I will have a short length of silicon hose connecting the tube to the neck on the radiator. A longer hose will then get me across to another aluminium tube that will run along the side of the valve cover above the exhaust (which will be heat shielded). I have a friend that's pretty handy with a TIG welder, so I'm planning on putting his skills to work on this job.

On the back of the head I currently have an M-TUNED coolant reroute block which has three connections:

1. Coolant hose.
2. Coolant temp sensor.
3. Coolant pressure sensor.

Sadly, it can't be spun through 180 degrees to send the hose left instead of right (it fouls on the gearbox) so I need something else back there. I'm probably going to use either an NB thermostat outlet neck with some fittings welded on for the sensors, or buy the reroute spacer and neck from Fab 9 Tuning: https://fab9tuning.com/miata-coolant-reroute-spacer-v2/

I have the remote thermostat from the M-TUNED kit, which I intend to mount either at the back of the head near the dipstick (independently supported), or possibly near the timing cover at the front of the engine. My preference at the moment is for it to be at the back.

Here comes a question...

1. What hardware have you used to successfully install a "hot-side" coolant reroute, especially at the back of the head?

[Scoota]

I had a proper go at fitting the M-TUNED coolant reroute block onto the back of the head upside down today. I was wrong... It can be fitted this way. The bottom bolt is a real pain to get to, but it can be done. I chopped a 6mm Allen key to just the right length for this fit-up.

IMG_0200.jpg

IMG_0201.jpg

It needed to be relieved on the bottom so as not to foul on the gearbox. A quick whiz with some files and sand paper sorted that out...

IMG_0204.jpg

IMG_0206.jpg

[Scoota]

I made some more progress on the coolant pipe brackets. These are finished and ready to fold.

IMG_0225.jpg

[The American]

They look very neat.

Is the material aluminium? If yes, how do you prevent cracking when folding?

[Scoota]

Thanks!

Yep, it’s 3mm aluminium sheet. I’m using a piece of 25mm box section (RHS), which has a nice radiused edge. It didn’t crack and gave me an inside radius of about 4mm. I just clamped both in the vise and used a wooden block and a hammer to gradually bend it over. Here’s some progress from tonight…









I’ll put a weld along this edge where the two folded tabs meet.


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[Scoota]

I've been making good progress on the hot-side coolant reroute. I'll let the pictures do the talking...

IMG_0294.jpg

This is what I have to work with in terms of new hoses and aluminium tube. These items are courtesy of eBay...

https://www.ebay.com.au/itm/261363445634?hash=item3cda79af82:g:McIAAOxy63FSwBn9&frcectupt=true
https://www.ebay.com.au/itm/251439445505
https://www.ebay.com.au/itm/261387475768
https://www.ebay.com.au/itm/251553875711?hash=item3a91c786ff:g:oMMAAMXQDnpTbeDD
https://www.ebay.com.au/itm/252296884587?hash=item3abe10f16b:g:38cAAOSw241YmFbY&frcectupt=true

A lenght of 32mm aluminium tube will be installed in the new brackets. A 90 degree silicon hose will give it some flexibility to allow the engine to move about independent of the radiator. I don't want my aluminium tubes to get stressed and crack. The thermostat housing will be mounted near the front left side of the valve cover...

IMG_0355.jpg

I managed to chop up one of my old (but still relatively new) hoses to get a decent layout at the back of the head. One of the 90 degree aluminium tubes was trimmed to achieve this...

IMG_0351.jpg

IMG_0349.jpg

The resulting layout looks like this...

IMG_0358.jpg

Yep, that should work.

Notes:
* Yes, I will be installing a heat shield between the exhaust and the coolant lines.
* The dipstick tube bracket was unbolted and the dipstick tube was "tweaked" a few times in order to make room for the new coolant line. More tweaks are likely. A bracket extension may be required.

[greenMachine]

IMG_0349.jpg

Yep, that should work.

That picture suggests the pipe will be a high point, above the level of the coolant in the radiator. A bleeder provision may be required to ensure air bubbles can be easily removed.

[bruce]

This might sound stupid; but considering the amount of stuffing around you went through, wouldn't it have been easier/simpler to get the radiator filler area relocated to the middle of the top tank in a straight line to your pipe over the extractor? Pay a radiator shop to cut that section off and relocate it and patch the old spot.
Plus there would be less points for any potential leaks/failure.

[greenMachine]

That's a good suggestion, if you have the headroom between pipe and bonnet underside. I have a redundant alloy header tank which would work with a little modification, LMK if interested.

I would not be rushing into a heatshield for those lines, once the thermostat opens there will be too much coolant moving for the radiated heat to have much effect. OTOH extended idling while hot, with the water pump at low revs, may stretch the friendship, depends on how your radiator/fan combination can handle that situation.

[Scoota]

Thanks for the feedback Bruce and GreenMachine.

GreenMachine, great suggestion. I’ll be putting a bleed fitting on top of the pipe at the highest point.

Socket:
[url][url]https://automotivesuperstore.com.au/raceworks-rwf-990-m12-a?utm_term=RACEWORKS-RWF-990-M12-A&utm_source=google&utm_medium=cpc&gclid=Cj0KCQiA0p2QBhDvARIsAACSOOMaysXZfrfZjvMMfC930Du4ZJMd1Qo3ErfKfqvRPHVd-2YKYd_e8loaAo4KEALw_wcB[/url][/url]

Plug:
https://automotivesuperstore.com.au/raceworks-rwf-814-m12-1bk

Bruce, regarding your suggestion to move the radiator top hose connection to the right hand side… I considered moving the entire top “tank” that has the filler and the hose neck, as per the picture...

Top Tank Move.jpg

I decided not to, for radiator efficiency reasons. The radiator top tank hose neck is on the right hand side of the radiator because the bottom tank hose neck is on the left. This creates nice even flow through the radiator. Without some testing I can’t say how inefficient the radiator would have been with the top hose neck on the left hand side, but maintaining “cross flow” through the radiator seemed like a good design principle to stick to.

GreenMachine, thanks for the offer of the header tank. Very kind, but I’m all good at this stage.

I know I’ve spent a lot of time on this, but I don’t consider time spent manufacturing brackets “stuffing around”. I find it quite rewarding. I’m in no rush (yet), and I’ve been hating the rush job that I did on my first coolant reroute for years. It’s been haunting me, whispering things like… “You should have taken your time and done it properly”. I’m taking my time and doing it the way I want to.

Regarding the heat shield... I’m planning a simple aluminium heat shield, nothing too fancy (wink). Well worth the time and effort, I reckon.