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

[Scoota]

Hi Folks.

Lots of great feedback happening here. Thanks for your input. I’m really going to have to look at E85, by the sound of it.

Regarding the valve springs... I’m playing it safe by getting the springs that perfectly suit the cams. Presumably higher rate springs, presumably marginally heavier, and hopefully they prevent valve float and other nasty phenomena.

Regarding suspension, I’m all good. The car is already running Bilstein PSS9’s, urethane bushes all round, adjustable sway bar links, and my own unique combination of sway bars, fine tuned over the years to give me the handling manners that I prefer and balanced front and rear tyre temps and wear. For interest only, I run the front Whiteline sway bar on the “middle” setting and the rear sway bar is... Deleted. Lightness!!

Further comments:

- Oil cooler? Yep, perhaps not necessary, but it won’t hurt. I’ll monitor temps and sell it if it’s not required. Testing required. I’ll be running an oil thermostat, so overcooling shouldn’t be an issue.



- Radiator? I was running a single core OEM unit (without issue), so an upgrade for this engine made sense. I settled on Mishimoto, as it was somewhere between the eBay jobbies and PWR awesomeness on price. Probably a fraction oversized, but I’ll monitor temps and consider my options. Testing required.



- E85? I’ve got some reading to do. I’m pretty sure the Adaptronic M1200 can drive the Flex-Fuel jobbie (I am vaguely aware of these devices).

- Hawk Blue pads? I’ve always run Hawks, and they’ve never let me down.

- Semi slicks? My experience is limited to Tokyo R888’s (average) and Nitto NT01’s. I’m really enjoying the Nitto’s for consistency and feel, and the price is right. Other tyres may be quicker, but I’m probably going to stick with Nitto’s for now.

- Rev limit? 7,200 rpm.

Intake
- ITB details: 4AGE Silvertop throttle bodies, which have a 43mm throat according to Google.
- bore size? 43mm.
- airbox or socks or YOLO(no filter)? Box, but I haven’t bought it yet. Suggestions anyone?
- Trumpet length? 75mm from Mannon Racing. Not the perfect length (apparently longer is better, but engine bay space is limited). I’ll shift my Wilwood bias valve to make room for it, but I’m expecting the filter box to be very close to the brake booster.

https://www.mrpltd.co.nz/product/4age-2 ... ty-stacks/



Fuel
- Injector size? 380cc, Flow Force from MX5 Mania:

https://mx5mania.com.au/products/nb-198 ... 4791&_ss=r

- fuel pump? Standard NA6 at this stage. I wonder if I need to upgrade...? Thoughts people?

- surge tank? Nope. Suggestions?

ECU
- Adaptronic M1200, to suit my NA6 loom. Engine sensors are a blend of B6 and BP, as per the “Car Passion VVT Swap” recipe, and the “VVT Swap Definitive Guide”. It’s all been done before.
- got a tuner? Yes, I sure do. My engine builder (Molinari Race Engines) usually works with Addicted Performance. I had a long chat with Fanks there, and he is happy with my choice of ECU, and seems confident that we can get it working, with VVT control. I don’t think he’s done a BP before, but I was very happy with his attitude after our chat. He seems willing to make it work with what I’ve chosen, so that’s a huge win in my book.



Exhaust
- Headers? Not yet. Recommendations? I would prefer not to have stainless headers, and I will HPC cost them inside and out.
- The rest of the exhaust is already high flow, perfectly suitable (can’t remember the size).

Budget? Ummmmm...... Blown. ...at least twice over. I’m in “just get it done” mode.

People, I want advice about coils!! I haven’t got replacements yet, but they’re on my radar.

Comments?



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[Magpie]

I can throw out some (possibly unwanted) advice, but keep in mind it is all based around an ITB car setup for racing.

Listen to Tim's advice, his car is fast and well sorted out!

Other people's build to look at are Shane Phol's and Madjack's.

Fuel
- Injector size? 380cc,
- fuel pump? Standard NA6 at this stage.
- surge tank? Nope. Suggestions?

If going to E85 those injectors will be too small, maybe ID725's also the fuel pump may need to be changed as well. You will also need to have them serviced often.

People, I want advice about coils!! I haven’t got replacements yet, but they’re on my radar.

COPS or coil packs?




Here is some data on my testing of different coils/plugs... This could lead to a question later on about how you will collect/compare data

IQQR 052319R2 is the new setup.
Bosch (0 986 AG0 503) from EFI Solutions. Plugs Denso IK24

IQQR 022119R3 previous setup.
OEM toyota ones and VDO branded COPs. Plug wise HKS M40i and for a few sessions an NGK 5671A-8 (non resistor

RPM smoother with new setup and EGT's show a better response to throttle.




EGT's for each cyl and each setup. There maybe a small difference in the plugs heat range as the Denso are slightly warmer (on average)


Average EGT


Voltage comparison

[Tim_cyc03]

I settled on Mishimoto, as it was somewhere between the eBay jobbies and PWR awesomeness on price.

I had one of these for years, no issue and are good.

- E85? I’ve got some reading to do. I’m pretty sure the Adaptronic M1200 can drive the Flex-Fuel jobbie (I am vaguely aware of these devices).

Is this a track only car or does it do road duties? What I'm getting at is if you do go e85 do you really need a flex fuel sensor and two tunes, as I feel that's just over complicating and an extra unnecessary cost.

- Rev limit? 7,200 rpm.

I guess this is more dependant on what your engine does on the dyno anyway. (should have said that before) No point shifting at 7,200 if it isnt right for the engine.

Intake
- ITB details: 4AGE Silvertop throttle bodies, which have a 43mm throat according to Google.
- bore size? 43mm.
- airbox or socks or YOLO(no filter)? Box, but I haven’t bought it yet. Suggestions anyone?
- Trumpet length? 75mm from Mannon Racing. Not the perfect length (apparently longer is better, but engine bay space is limited). I’ll shift my Wilwood bias valve to make room for it, but I’m expecting the filter box to be very close to the brake booster.

Have you already ordered this kit, or have it laying around?

- fuel pump? Standard NA6 at this stage. I wonder if I need to upgrade...? Thoughts people?

- surge tank? Nope. Suggestions?

I would imagine you will probably want to change the pump but honestly I don't know, however to save some hassle you can get a surge tank with an intank pump and use the stock pump where it is as a lift pump.

AI (should be local to you I think) https://www.aftermarketindustries.com.a ... ustries-m1 or Radium Engineering both do decent units. I have used both.

Exhaust
- Headers? Not yet. Recommendations? I would prefer not to have stainless headers, and I will HPC cost them inside and out.
- The rest of the exhaust is already high flow, perfectly suitable (can’t remember the size).

Off the shelf I would be looking at Racing beat 4-1, or Maruha Motors 4-2-1. From reading (as I haven't tried different headers on the same engine) typically 4-1 for max power at high rpm, and 4-2-1 for better mid range torque. The mid range is more important by far for a track car, but RB state they have been able to maintain the mid range with their 4-1.

This is quite an important choice, and there are many more out there that I haven't mentioned, don't skimp here or you will regret it.

People, I want advice about coils!! I haven’t got replacements yet, but they’re on my radar.

Comments?

You don't need them.

[GR124]

Regarding E85, I haven’t actually given it much thought, but I won’t rule it out in future.

As for power expectations... Who knows?!
In NA6 form my car made 78kW on semi-slicks on the dyno, so anything north of 100kW is going to be a significant upgrade for me. Realistically, 120kW is probably within reach. Figures like 140kW, and even 200Hp, have been bandied about, but I’m not holding my breath. I’ll be happy if it’s running and good to go for November.

FYI - My track BP4W engine has standard internals, 4-1 headers, upgraded injectors, haltech, so very standard on E85, 141whp

[rascal]

FYI - My track BP4W engine has standard internals, 4-1 headers, upgraded injectors, haltech, so very standard on E85, 141whp

Was that figure with different (bigger) cams, or with standard cams? ("standard internals" can mean different things to different people)

If standard cams, then that 141whp is very high for a std-ish BP4W...
Normally stock with I/H/E & ecu are around 110whp, and e85 is usually about 5-8% so that would make it 120whp at best...

[GR124]

FYI - My track BP4W engine has standard internals, 4-1 headers, upgraded injectors, haltech, so very standard on E85, 141whp

Was that figure with different (bigger) cams, or with standard cams? ("standard internals" can mean different things to different people)

If standard cams, then that 141whp is very high for a std-ish BP4W...
Normally stock with I/H/E & ecu are around 110whp, and e85 is usually about 5-8% so that would make it 120whp at best...

Unopened engine, standard cams. We all know dynos are not all equal, maybe it needs calibrating

[Scoota]

Wow Magpie, that’s an impressive array of data. I’m a long way from that sort of testing, but it’s nice to see an example of a pretty high standard of testing. Nice work!

Regarding my setup, I think I’ll go with Tim’s advice at this point. I’ll run with the OEM coils for the first tune. If my tuner finds them to be limiting, I’ll consider my options.

Regarding E85, I’m still undecided, as I haven’t had time to research anything yet. That’s a loose end that I will need to tie up soon though, especially if that decision impacts injector and fuel pump size. Standby for more news on that front.

Thanks for the feedback and the quality info!



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[Scoota]

Okay, now to look at some of Tim’s queries...

Firstly, thanks for such a massive contribution thus far Tim. I’m really enjoying the discussion.

- Is this a track only car or does it do road duties?
Yes, it is purely a track car.

Regarding E85 and the flex fuel sensor, I have to admit to knowing next to nothing about it. I won’t embarrass myself further here until I’ve done some research. As per the post above, I’ll do some reading and get back to you with a decision soon. It sounds like a good thing, but I need to consider the complexity and my timeframe. It might be something I do later, perhaps next year. Standby for news on this front.

- Rev limit? 7,200 rpm.
You are right Tim, the engine will determine this, to a degree.

Here’s a general comment about what I’m hoping for regarding power and torque curves... Tim, you are right in saying that mid-range is very important for track cars, and that’s what I’m building. I’ve done all sorts of events: motorkhanas, autocross, khanacross, hill-climbs and sprints. I’m definitely after an engine that is strong in the mid-range, but still with an appetite for some revs, like the good old B6. I bloody love that engine. I’m essentially hoping for something similar with this build, but with much bigger kahunas, if you get my meaning. I’m definitely not after a peaky 9000rpm screamer that is useless below 6000rpm.

Another general comment about this build... I am having to make lots of decisions in a short timeframe due to my commitment to Challenge Bathurst 30 Nov/1 Dec. That means that some things aren’t being researched exhaustively, if you get my meaning. I’m doing this with the understanding that I may get a few things wrong.

This is by no means a definitive guide on how to build the best big-bore BP-Z3. In reality, it is just my story, documented for your benefit and mine, hopefully. And also for our collective amusement!!

Tim, I’ll try to address the rest of your questions in detail tomorrow, but here’s a quick reply...

The ITB recipe was given to me by Russell Garner, a fellow Vic MX-5 club sprint competitor. It’s worked for him, so I’m giving it a shot. It’s a long story, so I’ll save that for when I have time to tell it properly.

Thanks everybody!

Comments?


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[Scoota]

Hi Folks.

I’ve been browsing for a decent set of headers and I keep coming back to the X-Force design. I ran a set of X-Force headers on my NA6 for about 6 years, and I really liked them. I had mine HPC ceramic coated inside and out. Sadly, they cracked over the years, twice. Luckily I have access to a Tig Wizard (my mate Bourkey), so it wasn’t a huge issue. Reflecting on this, perhaps the ceramic coating was a factor, as I think it’s a hot process. Dunno. Thoughts? Stainless cracks, I get it, but it’s still disappointing.

Do you guys have any comments on the X-Force headers? They have a 4-2-1 design (for good mid-range punch) and they appear to be “balanced length”, with each run having equivalent length to the last convergent point. I’m not an exhaust guru, but that’s a good thing, right?

I’ve already approached X-Force to see if they will make a non-stainless set. They won’t.

They seem like excellent value. Comments or suggestions?


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[Magpie]

As Tim mentioned, Racing Beat is the most popular. Shane P was going to do some testing with different headers but not sure if he got around to.

Another header source:
http://www.cesracing.com.au/products_5.htm

I will see if I can find the dyno plots for when different trumpet lengths were tested on mine as well as the 98/E85 plots.

[Scoota]

Thanks Magpie. Regarding the Racing Beat headers... They certainly have the best spiel on their website, but I’m not convinced with their design. They appear to be more top-end focused, which is not for me.

The CES headers... Wowee. They look very nice. I like the fact that they are milld steel too. They ought to be less prone to cracking, so that takes them into the #1 spot for me so far. Being Australian made is a nice bonus too.

I’ve just consulted my (offline) brain’s trust and we all agree... The CES design takes the win with regard to my preferences and this build, for these reasons...

• 4-2-1 design, which typically provides more mid-range punch.
• Balanced length runs to each of the “Y’s”, which ought to generate more scavenging effect (remember, I’m not a guru, just quoting people that I reckon know better than me).
• Mild steel construction.

Another decision in the bag!!

I’ll be ordering a set of those shortly, and I’ll trundle them off to HPC myself. Luckily for me, HPC’s Leongatha workshop is a short drive from home for me. Sounds like a good excuse to get out for a fang in my other weekend toy...





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[plohl]

There's so much more I could add... but anyway.

I have had a quick look over the thread. Some comments.

Don't waste your time with ITBs. More hassle than they're worth. The flat top manifold from the vvt engine is more than sufficient until you have massive port work and bigger cams. Build an intake pipe to go in front of the radiator about 1100mm long - it'll give you good intake air temps and help with the harmonics.

Make sure whoever is doing your engine build checks the piston to valve clearance at full retard and full advance on the vvt cam. You might have to mechanically limit the VVT range so you don't mash sh*t together. Cam timing will play a big part in where you make power, lots of overlap = lots of mid range power. This could mean you're setting the exhaust and intake valves from 2 - 3mm lift at TDC - or more in some cases, but this again will impact how much you can use the VVT.
You pretty much have the vvt "off" above 4500 rpm anyway, so on most of the 2f cars up here using the vvt engine, they just remove it.

You don't need over sized valves. Some of the fastest naturally aspirated NA/NB mx5s are using standard valves.

If you want a good set of headers, check out CES in queensland - their headers are on most of the fast cars up here. If you want a full system that'll fit - spend the money on a racing beat system. I had one on my car for a while and it was great - but it won't give you the best power. Get the one without the resonator.

The bottom end doesn't really have too much to do with power in an NA - the head is all the difference.

Somethings to consider:
Make sure you know the compression ratio - don't rely on the piston manufacturer. Measure it with the head and gasket on the block.
Know your squish clearance.
Get good bearings and have the crank crack tested.
Don't worry about coils
You might have to get colder plugs. Me and Tim both run bkr8e-11
Buy a mechanical diff, 1.5 way. OS giken if you can afford it.


And last but not least, don't bother with ITBs... Unless you really want them I suppose. Regardless, they won't make you faster.

[Scoota]

Okay, I just ordered the headers. Trevor at Custom Exhaust Specialists in Meadowbrook QLD is an absolute gun!!!

He asked me a bunch of questions about my engine and he is going to fine tune their design to exactly suit my engine, at no extra cost!! $790 plus freight, unpainted.

He even recommended something a bit odd... He’s recommending a step up to 3” from a point somewhere beyond the headers (he needs to calculate it), which does.... something that I don’t understand, but I want!

That was one of those awesome phone calls... I’m impressed with his attitude and I’m very happy with my choice. He came across as an exhaust specialist that really knows his craft.

So happy!!!


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[Magpie]

There's so much more I could add... but anyway.

I always value your posts Shane!

CES are very professional!

[Red_Bullet]

I have a CES system, so this makes me happy.