Just Another F20C build... <Preview>
 

My F20C build is scheduled to start at the end of June. It'll mostly be done by a local race prep shop, with a little help from me when I have time.
I picked up the engine, 'box, manifold, ECU and loom last week. Today, I took the car to the prep shop and we got down to a bit of serious measuring.
My aim has always been to put an F20C in the car without moving the steering rack, and today, we figured out a way to do it. It won't be easy, but it will be the most ideal solution from a performance point of view...

Anyway, here's a few (rubbish) photos from today. They're all cropped to hell, in a very noobish fashion, to make sure they creep in under the 1200 pixel width. Also, I'll get hold of a better camera when the build starts to avoid an orgy of internet photo-flaming by you lot ;) But for now, deal with it :fawk:

It starts tomorrow. I'm unbelievably ridiculously excited. So updates and photos will follow shortly.
After seeing so many people on here say "do it once, and do it properly", that's exactly what I'm going to try and do. I've worked like a nutter for a year, and I'll be doing everything I want to do to this car over the next two months. Bushes, dampers, half cage, tyres, 'adding lightness', carbon buckets w/6 point harnesses.... and an F20c engine and 'box moved back 8", through the firewall, with the driving position being shifted back 6".
Did I mention I'm excited?! :noes:

Looks like this will be a proper build that will kick ass. Good luck and good job so far.

Much better pics needed but you're definitely on the right track to a winning build thread:D

Thank you :)

I guess that is how you are going to make it work without modding the steering rack...

Yes. That's what is required to clear the rack. The engine to gearstick length (you know what I mean!) is 2" shorter on the F20c, hence only moving the seat, pedals and wheel back 6". I'm only 5"6, so the seat can be simply bolted back where it needs to be with no further modification.
It'll be interesting to see what it does to the weight distribution. The F20c engine is lighter and the gearbox heavier, which shifts it back even more. Once we've messed around with battery location etc, I think we'll be able to get it pretty damn close to 50:50.

Car is now off the road for a couple of months, and I have a very ropey 200k mile Audi A3 to drive around in. It's comfy, it handles in a hilariously uninvolving way, and that's probably the last I'll mention of this Audi unless I crash it, which is semi-likely.

The Mazda's dash is coming out on Monday in order to start the electrical work. Things will happen reasonably quickly now, which means half decent photos will also, at last, start to appear this week as stuff gets under way.
Also... John Barker from Evo Magazine (UK car mag) had a poke around my car today, and a poke around this project in general, and he likes it a lot. I've read Evo mag for over a decade, so this has kinda made my day :D

Edit - Below is a photo of my car in a workshop. Exciting, huh. The other photo is of a custom dash for a very old Bentley (the racing green one next to the Caterham in the first post photos) that will cost the owner almost as much as the labour for my entire project. No joke :eek:

So, so in for this. I love that you're going the extra mile to keep the weight centered in the chassis. Bravo, sir.

Great looking build you've got going.

Is it being built by the same people who recently finished rebuilding JB's Capri?

Yes it is. Did you used to own a red Begi'd mk.1 btw? Circa 250hp? That was the first turbo mx5 I drove. I'd still love to know what the spec of the brakes were, 'cos they felt great.

Not me, I've never owned a Red one. I currently have a FM/homebrew Rs-ltd.

Ah sorry. I'm getting confused with GrahamC, who's also on mx5nutz.com like yourself.

THERE'S A FUCKING HOLE IN MY CAR.



Where the engine used to be.


The engine came out the car today. After more measuring, Quent (boss of shop) and co have come to the conclusion that the gearstick will be coming back 4 inches, not 6, assuming a half inch gap between the steering rack and the front of the engine. Cutting right into the bulkhead is still going ahead as planned.
The car was corner weighted with pressure gauges before anything started. The front:rear distribution was 52.5 : 47.5. Which puts us bang on course for achieving a 50:50 weight distribution as a handy bonus as a result of moving the engine back to avoid moving the rack. Did someone say 'two birds with one stone' ? :idea:

Any miata colour experts out there? I need to decide quite soon what colour to paint the engine bay. I was going to go with just plain old black, then red, then...... maybe the body colour. Problem is, I don't know what the body colour is called.
As a 1995 R Limited Eunos, it 'should' be Montego Blue. But it's not. Montego blue is a blue/green, and this is a blue/purple. The overspray on the inside of the doors looks basically purple.
After much Mazda Miata colour internet geekery, I've narrowed the colour down to one of the following: Stormy Blue, Strato Blue, or Twilight Blue. Either way it's strange, because according to everything I've ever read, Mazda didn't do a blue/purple NA.
So, any suggestions as to what the hell this colour is?!

No idea on the color but I am definitely in for updates...

Another hole appeared in my car today. This time, the hole is where part of the bulkhead and all of the dash used to be.

So, the dash is out. Unsurprising news on the instrument binnacle - the dials are attached to a PCB. This probably means that I won't be able to simply take out the existing tacho and insert an 80mm Stack 0-4krpm, 4-10.5krpm tach as I had planned. Instead, I now have a FANTASTIC EXCUSE TO BUY MOAR STACK GAUGES. Likely candidates are Stack 80mm tach as mentioned, 80mm speedo, Stack Pro oil pressure, Stack Pro oil temp, Stack Pro water temp, and Stack fuel level gauge.

Other news - We need to work out what to do with the heater matrix. It's obviously right behind the bulkhead. In terms of whether the engine will fit behind the rack and come through the bulkhead and still clear the matrix, it's "very tight" at the moment, apparently. I had a good look at it after work today, and I see no reason why said heater matrix can't be moved backwards maybe 20mm, perhaps fractionally out of the dash. The guy there when I turned up was someone who wasn't working on my car, and he wasn't sure of how much clearance needs to be found. I'll find out tomorrow. I don't think it'll take long to find a decent solution.

Further news - I forgot to take my proper camera, so here is a single phone photo. If you close one eye, then squint pretty hard with your remaining eye, the photo quality looks excellent.

Very cool solution to the steering rack issue. Will be watching this build closely. The car will effectively be a mid engine miata, very cool. Interested to see how you handle the exhaust.

One bit of advice, take tons of pics, once you have done that take a bunch more. You can never have to many photos when documenting a build.

IMO one shot of the heater is not enough. You need several pics to allow us to see what is happening.

Keep us posted

I love hybrid cars and this one will for shore be a good one. I am in for updates as the come.

Thanks. I'm aware that you and everyone else have moved the steering rack, so I need to choose my words carefully here - in my opinion, moving the steering rack is an extremely sub-optimal solution. If I had to move the steering rack - which would certainly corrupt the steering in some way, no matter how you went about 'fixing' the geometry - I would not put this engine in the car.
Quent is taking LOADS of proper photos documenting the build as they work on the car. I need to arrange getting them off him as we go, 'cos at the moment, we're on course for me taking a few crap photos, then the build finishing, then about a hundred decent but out-of-date photos getting uploaded. So I hear you on the photo thing.

We've looked at the exhaust in great detail. I have some ideas, and Quent has some ideas. I've been researching back-to-back dyno plots and owner research on the Naturally Aspirated section of the s2ki.com forum. Those Honda guys get very, very into their details, and spend serious time, effort and money conducting research on their engines, which I like. Long story short, the result of me reading up on this F20C engine is that this car will be running no cat, I'll be retaining the standard manifold (header), the exhaust pipe diameter will flair smoothly from the manifold donut gasket up to 70mm, I'll run a single silencer (no resonator), and I will, of course, be running the exhaust the neatest way I can out the back of the car. Or, possibly, dumping it under the car. A side exit looks tricky at the moment. Also, trackdays generally have around a 100db drive-by noise limit, so that's also a consideration. Although I'm tempted to not be held back by that and just do what's best for the performance of the engine without deafening myself, and deal with the trackday noise limit situation when it arises.

LOL, no polite way to say I think your solution sucks.
But, I'm okay with that. Looks like I need to throw my track tire and brakes on and take a proper video of the car on track. Here are the facts of how this car works, steering is light and predictable, no rub of tie rod to wheel, stable under braking. The best solution? No, but I personally wouldn't go the route you are going either. Also, I had the engine cranny combo bolted in the car in one weekend.

I am in no way offended that you don't like my solution, but you can' t argue my results.
Build pics showing all progress please.

I can't argue with your results at all, and I'd still kill for your car. The power must be insane. We've both just got a different philosophy on cars I think. I reckon I'll generate a fair bit of confusion regarding the other choices I'm making with this build. For example, I'll be running 185/55 r15 tyres, and spring rates around one third as stiff as many members here. All depends on what YOU want to get from the car.
That said, the clubroaster lot are still gays and I will never understand the choices they make, ha.

Ha ha how to endear yourself to mt.net in one easy step :D

Well said. Every car guy has a vision for the project they are building. I think an important question to ask is what are you building? Will it be DD that sees the occasional track day, a dedicated track car, will you be running auto x? Soft springs lead me to believe you are buinding a fun DD type commuter.

I should have outlined my plan and idea a little better in the first post I think. Here's a long-winded clarification (ha) of what I'm aiming for:

This car will be a daily-driven road car. I might take it on track occasionally. I'm a go-karting guy, and that tends to be where I get my track fix. I do, however, regularly go out late at night on the back roads for a thrash. I'd have a Caterham as a DD in a heartbeat if I could fit anything in one.
I bought the Miata because it didn't have much grip, and had excellent chassis balance and adjustability. For me, that makes it a lot of fun. With this build - aside from inserting an engine which I think fits the whole vibe of the car - I'm aiming to keep grip levels more or less the same, make the steering better (after driving a non-power-assisted car, I know my Miata has the potential to have excellent steering), increase the stiffness of the chassis a bit, lighten the car as much as I'm prepared to, and importantly, fully resolve the damping. The dampers I'm choosing for the car are being valved by an ex-Lotus guy, and I want the ride to be as Lotus Elise-like as possible. A particular Elise remains the most impressive car I've ever ridden in, just because it was more comfy than a Volvo, yet very well controlled at all speeds.

For those in the States, bare in mind that our roads are often a lot bumpier than yours (and yes, I have been over the pond to see for myself!). Consequently, a more softly sprung car is often preferable. Even with 185 section Yokohama AD08s, I think I'll still generate more grip than a standard Miata, if the damping is nailed. 185 section tyres are obviously lighter, and less prone to bump steer, than a wider version of the same tyre. The 6" wide OE BBS rims on this car are slightly lighter than 7" 6ULs, so I'll be keeping hold of them. In fact, I don't intend to change the exterior of the car at all.

Thank you for clarification, looking forward to following your progress. You won't be disappointed with your engine choice, I used mine as a daily for approx 6K before I decided to boost it and turn into a toy.

I didn't get a chance to nip over to the shop after work today, but I did call them to get the latest news. Turns out that the heater matrix does not need to be moved in order for the engine to clear the 'rack. That's about the only update, but I think that's encouraging info for anyone wishing to go down this path in future :)

Interested to see how the engine sits in there. Wondering about servicing the engine and adjusting valves. Also, holding my breath to see how you handle the exhaust. It's pretty easy to hinder flow, and ruin the free, high revving spirit of these engines.

Moar info re your concern about adjusting valves please.
The oil filler cap will, of course, be under the windscreen. Working out a way to get it off and top up the oil shouldn't be too hard.

Re the exhaust, as I've said, I've done a shed load of research into what these particular engines 'like' when it comes to their exhaust. Hopefully I won't have to make any compromises. Quent mentioned flattening the exhaust slightly when it transitions from one side of the drivetrain to the other to ensure decent ground clearance, but obviously maintaining the same cross sectional area to avoid a bottleneck. In theory, this sounds great, but I think maintaining EXACTLY the same cross sectional area would be very tricky in practise, and would be exactly the kind of thing that would strangle the engine if it was more than a few square mm out.

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Great build.

The top of the valve train sits just under the valve cover, If you are having to work out how to get the oil cap off, my concern is that it will be impossible to get the valve cover off to adjust valves. The valve train is rocker under camshaft, the adjusters are at the end of the rockers over the valve stems. As you can see from the picture with the guy in it (not me by the way) there is a lot of mass above the mating surface of the cylinder head to valve cover. You need a lot of clearance above the valve cover to remove it.
http://i408.photobucket.com/albums/p...adjustment.jpg
Attachment 187441
Just thinking out loud.

That's a good point mate. How often would I need to adjust the valves though? That's something I haven't come across in my research.

Is that a colored standing there in front of old dixie? As a southerner, I am truly disappointed.

After further research, I don't think it'll be necessary to adjust the valves much.... if ever.

I'll upload some photos later tonight. I have to go bale carting on the farm. Which will be SO MUCH fun, especially after a day on a construction site. :facepalm:

I think Honda says 90k, I just don't like the idea of valve adjustments once every hundred thousand miles on an engine that spins to 9. But that's just me.

More pics and descriptions in a bit...


Descriptions, from left to right:
- New dash is in the Bentley. Looks a bit too 'new', but the brass should tarnish nicely. Quent's busy wiring it up.
- Photo taken from the (UK) passenger footwell, looking directly across the firewall, showing the clearance between the firewall and the heater box.
- Another shot of the initial cut out in the firewall.
- Looking from the engine bay back through the trans tunnel. The corner of the driver's footwell (on the left of the photo, with the lines running under it) will be cut out and reversed. This will give more room for the exhaust manifold, and also give me somewhere to rest my foot when driving, ha.
- Looking down into the engine bay. The galv tube is in the place of the steering rack. You can see where Quent has cut the crossmember. New crossmembers will be fab'd up both in front and behind the steering rack, for strength, stiffness, and for a handy place to put the battery...

I've exceeded my attachment quota apparently. Hmm. Someone please tell me how to post photos in the thread itself like all you web-savvy kool katz do.

Try again :)

damnit use imgur!!!! Embed in thread!

You can embed her too. He was a reg user who exceeded his quota. I removed it all together.

I feel loved.

Holy crap it worked. That's a pic of the crossmember section that's been cut out. Here's some more:

https://www.miataturbo.net/attachmen...ine=1310675865
Notice the pretty substantial PPF mount on the Mazda gearbox...

https://www.miataturbo.net/attachmen...ine=1310675865
And the lack of mount on the Honda 'box. Quent is going to get his machinist to machine a block of aluminium which will use the two existing mounting points on each side of the gearbox, and will wrap around the top of the transmission. This will be further supported by bracing running to all other available existing mounting points on the box. This is how the PPF is being mounted.

https://www.miataturbo.net/attachmen...ine=1310675865
The manifold heat shields take up too much room, so will be removed. I'll wrap the manifold, but probably with a non-baller one piece heat shield, because I'm worried about the mild steel rotting away if I wrap it both tightly and in such a way that I can't easily remove said wrapping. I won't be getting the manifold ceramic coated because I'm not THAT baller. One nil hingstonwm ;)

https://www.miataturbo.net/attachmen...ine=1310675865
Annoying sticky-outy cam angle sensor is annoying.

https://www.miataturbo.net/attachmen...ine=1310675865
This is what the back of a '95 Eunos dash binnacle looks like. Obviously, it's one big printed circuit board. As I've mentioned, the inability to remove and replace just the tacho means I'll be replacing all gauges with Stack items.

I managed to get over to the shop today for the first time in a week. The engine's in for the first time to check the fit. Turns out there's still a fair bit more cutting to do :P The engine also contacts the heater box, just. Basically if I want to retain a sane amount of clearance, I'm going to need to do something about the heater box, more details of which soon. Here are some photos from earlier today:

https://www.miataturbo.net/attachmen...ine=1311366419

The galv tube is of a slightly larger diameter than the 'rack. As it sits, the engine clears it by approx 5mm.


https://www.miataturbo.net/attachmen...ine=1311366419

Appears to be touching in the pic above, but there's actually reasonable clearance.


https://www.miataturbo.net/attachmen...ine=1311366419

I wanted the engine to sit low. A sump guard will be made if necessary, but bear in mind that this car won't be running much lower than standard '95 ride height.


https://www.miataturbo.net/attachmen...ine=1311366419

More cutting required to allow the exhaust manifold to be removable without dropping the engine. I obviously looked at it today, and in my humble opinion, there's plenty more material that can be cut away from this area on both sides, because the stiffness could be put back in with some carefully placed bracing. I told this to Steve, their machinist, who was the only one left there at the end of today, and he agreed, so I'll see what they do next week.


https://www.miataturbo.net/attachmen...ine=1311366419


https://www.miataturbo.net/attachmen...ine=1311366419

Oil cap may be plugged and moved to the front side of the valve cover at this rate. Worries about interference with the wiper mechanisms was mentioned.

Use a manual rack and move the engine forward, most likely it will give the extra clearance needed for the heater box. The manual rack is much smaller in diameter than the power rack you have in your pics.

It is, but it's also a slower ratio. I'm having the power rack depowered and welded up like so: http://www.motoiq.com/magazine_artic...ring-rack.aspx

For your purpose the slightly slower ratio ain't make a difference

I just prefer a faster rack :)

More cutting has been done. The exhaust manifold is on. Looks increasingly like I'll have to drop the front subframe assembly to drop the engine.... but that's fine. The bottom of the manifold sits about 30mm (I didn't measure it) below the frame rails, so it's pretty low. I spent ten minutes looking at the exhaust, and I think a side exit, just in front of the (UK) driver's side rear wheel, using an approx. 6x14 inch round muffler, is achievable. Side exit exhaust = less weight, and also..... erm...... well..... well frankly I just find side exit exhausts ridiculously cool, ha!
Apparently the main guy working on my car knows what he's going to do with the heater now, and it involves cutting into it, but not losing the flaps.
I can't think of anything else interesting/new to say right now and didn't get any pics (the shop is still taking copious amounts of photos as they go) so that's it for today folks.

Side exit exhaust, how much ground clearance do you figure on having?

The side exit shouldn't encroach on ground clearance too much. There seems to be enough room between the back wheel and the main structural part of the sill for a three inch pipe to sit level with the normal sill height. the muffler might hang slightly lower than the frame rails. So it's not like it's going to be hanging under the sill. I'm fucked for ground clearance anyway what with the manifold already hanging below the previous lowest point on my car, so sod it :P
Good job I hadn't planned on lowering the car much, huh!

Are you using the stock manifold? That thing weighs a ton. I used a DC sport header as a starting point, then modified it as needed. I will have to try and find my dyno sheet from when the car was na, Maybe I gotucky but my power was not compromised at all.

Yes I am. I hadn't budgeted for a replacement, which means (contrary to shlammed's GIF above) I don't have the money for a decent one. I originally hadn't budgeted for a replacement because the standard manifold is pretty well designed, as has been proven with a number of back-to-back dyno tests over on s2ki.com. Approximately half the well-known aftermarket manifolds either gain about 2hp, or lose power. The best (generally agreed to be Hytech, circa $1.5-2k) without touching the ECU, makes maybe 7-10hp at the most. If I was extensively modifying the engine I'd buy a manifold to match, but for a standard engine, the standard manifold works very well indeed.

Saying that, I hate excess weight with a passion, so by telling me the standard manifold weighs a lot, you've made me sad. Darn it. :cry:

https://www.miataturbo.net/attachmen...ine=1312489214

Exhaust manifold on. The manifold studs will be replaced with bolts to allow the manifold to be pulled without having to drop the engine. As it sits, there's no space to slide the manifold off the studs.

https://www.miataturbo.net/attachmen...ine=1312489214

This is a shit photo, but I thought a shit photo is better than no photo (just) so I've thrown it up here. It's looking across the sump, and is to show that 1) the sump plug sits handily just below the chassis; 2) the subframe can be braced directly between the two rear lower wishbone mounts, and just ahead of the front lower wishbone mounts. Obviously it would be best from a structural point of view to be able to brace directly across from both of them, but the sump sits in line of the front wishbone mounts, so a section will be made that goes around the sump. But basically, it will be possible to brace the subframe up in a way that will make it probably stiffer than it was originally.

Also - the side exit exhaust will happen. The manifold donut gasket and the bit before the gasket (the....tertiary pipe?!) is being replaced by a slip joint, because it's lighter and means the tertiary pipe can be pointed in the right direction instead of off at a slight angle as it is at the moment.
The tran tunnel will be enlarged slightly. There'll be enough space for the pipe to flair up to 3" from the manifold, run straight back, then turn 90 degrees before the rear wheel, then have roughly a 6"x14" muffler. Then the exhaust will exit either just in front of the rear wheel (cutting into the angled non-structural sill part that's there), or exiting downwards with a slash cut. Quent thinks exiting it in front of the tyre is a bad idea because of the amount of heat it'll be putting into the rubber. I suggested wrapping the muffler and tip, and he countered by saying the wrap will very quickly get covered in crap after a few days of daily use. So I don't know what will happen with the exit yet. One thing's for sure though... it won't be quiet :giggle:

It's handy working at a steel yard. Quent wanted a jig for the exhaust flair and slip joint just after the manifold. It just had to be a bit of tube with the same o/d as what I'm using for the exhaust. So I grabbed ten mins after work and used a bit of 304 stainless as so:

Giving it a quick polish:
https://www.miataturbo.net/attachmen...ine=1312565786

And bandsawing:
https://www.miataturbo.net/attachmen...ine=1312565786

Then gave it a quick once-over with a 4.5 inch flap disk, and took it to the shop. So the exhaust manifold slip joint will hopefully be fabbed up this week, then I'll be making the exhaust myself.

Lastly, here is a photo of two ladybugs having sex.

https://www.miataturbo.net/attachmen...ine=1312565786

I bet this thing is gonna scream. Keep up the good work.

I'd like your thoughts on seats please guys :)

So far I've been absolutely set on Tillett B5s, mainly for weight reasons. The carbon/grp version weighs in at under 6kg (13lbs). http://www.demon-tweeks.co.uk/Motors...Seat/1761/1047

However, I just realised that Recaro Profi SP-Gs weigh near-as-dammit the same amount... http://www.demon-tweeks.co.uk/Motors..._Seat/1761/992
Suddenly, all that extra padding on the Profis is looking pretty tempting. I've experience of Caterhams with unpadded seats, and have sat in Profi SP-Gs. Both were comfortable, and I like the minimalist approach of the Tilletts, but I'm trying to imagine if getting into a big squishy Recaro every day would be more fun that clambering into a solid carbon bucket. So far I'm not sure. Thoughts, anyone?!

I'm going for Profi SP-Gs.

Engine mounts have been made, so the engine now sits where it'll sit. The proper rubber (rally-spec mounts, not sure what exactly they are called) hasn't arrived yet so it's still being supported by the hoist.

https://www.miataturbo.net/attachmen...ine=1312916269

Final engine position. Not THAT far back really. Interestingly, it's not even as far back as the engine normally sits in an S2000. Still a fair few inches further back than the standard BP location though:

https://www.miataturbo.net/attachmen...ine=1312916269

Note the heater box clearance now that the engine has been pushed further forward... interesting. With a few adjustments to a couple of sensor positions, minimal heater box disemboweling will take place:

https://www.miataturbo.net/attachmen...ine=1312916269

Holy chopped up PPF !!!11!1!!!!!!1! (......obviously cut down to match the decreased distance between the gearbox and diff):

https://www.miataturbo.net/attachmen...ine=1312916269

Any excuse to post a photo of the Cosworth BDA in this rallying Escort, that's in the shop again being worked on, is fine by me. Hopefully my engine bay won't look too dissimilar once completed:

https://www.miataturbo.net/attachmen...ine=1312916269




Lastly, here is a photo of me in a dress looking like a douche.

https://www.miataturbo.net/attachmen...ine=1312916269