Cus' NA6

[Cus]

The only real snag was the locating washer thingy.

I removed the diff from my NA a couple of weeks ago and also struggled with the "thingy". In the end, after managing some initial separation with a chisel, I had success with a small claw hammer. Not saying it is the best way to do it, but it worked for me and my limited tool set.

We had a... I don't know, a glorified chisel/scraper thingy that's designed to be beaten with a large hammer. We used that - and a large hammer, of course - to get it started (after drowning it in WD40), then used multi-grips to twist it out once it started moving.

We got the diff in this arvo, Myself and the brother-in-law under the car moving and aligning things, my sister operating the jack and reading out torque specs from the service manual, and their two little ones alternating between watching adventure time, helping, "helping" and running amok. Putting it in was really easy, I was convinced there was a step we'd missed, it all just went in without too much fuss - even with the butterfly brace and the exhaust still in the way (we couldn't find a tool that would get the bolts out of the butterfly brace, they're 19/32" bolts or some kind of stupid american size)

I was worried that the speedo would be out, so fired up the GPS speedo app on my phone and went for a drive ... I'm pleased to report - it's now exactly correct (it was about 5km out at 100km/h) and 100km/h is now just over 3000 RPM on the tacho.

[hks_kansei]

yeah, tbe NA8 onward diff went to a 7inch ring gear, from the 6 in the NA6

the half shafts are an nb specific thing, NA8 ones use a flange arrangement like the NA6 (diff size though, so not interchangable)

the 1.8 diff centre is the more flexible option, since it was shared with a few other cars (rx7, and i think S2000 (dont quote me))

[Cus]

We had an MX5Vic club run yesterday, down to near the GoR for dinner, then a dusk/twilight run along a part of the Great Ocean road, then home.

500-and-something K's all up, tops down, rain smashing me in the forehead for a good half hour along the GoR.... you have to be a certain kind of crazy, which apparently I am, because it was AWESOME.

I'm please to report that the Diff didn't fall out of the car. ...the exhaust did though.... When putting the exhaust back on I was umm'ing and ahh'ing about replacing the bolts that attached the extractors to the rest of the system, they were getting a bit average (binding up), but decided against it.

45 minutes from home I went through the maccas drivethrough and collected some "food" then went through a drug-bus (good news; I wasn't on drugs), then pulled up to eat just outside town. Turned the car off, put the radio on, fed myself some food, and started the car. "that's loud" I think.

Revved it up to drive off, and it was really loud, even more so while going uphill. No tools, hot car, lowered car, middle of the night, middle of nowhere ... the decision was made to drive it the rest of the way home, as quietly as possible - which was not very quietly.

A huge thank-you to the universe for letting me get through the police checkpoint before the exhaust fell off!

Inspection this morning shows that both nuts had fallen off the bolts, and if the butterfly brace wasn't on the car, some serious damage might have been done. Luckily the butterfly brace caught the exhaust. My brand new exhaust gasket is gone (i did replace that .. all $5 of it or whatever) and I now have different sized bolts holding the exhaust in place (with crush washers) because the local hardware shop has 900 different kinds of bolts, most of them for building fences and barns and not for anything even remotely car related....

[Cus]

It seems my new job has had a serious effect on my MX5 road-tripping antics....

Good thing I've got the next 10 days off work!

Oil Changed, diff oiled and installed, fresh Hard Top "Plate Deck Lock"s installed, exhaust attached, wheel nuts torqued, new fuel filter packed (but not installed) ...

... TO THE MOUNTAINS!

[speed]

Build it and they will come. Oh wait.. that's field of dreams.

Good to hear that you have time off to enjoy some twisties

Sent from my GT-I9506 using Tapatalk

[Cus]

I'll only be 400-ish km south of you, if you need a reason to go to the mountains ;)

[speed]

Raincheck? I'm cool to meet halfway between Sydney and Victoria but still have a few things I'd like to get sorted first, before I embark on a Cus like trip

Sent from my GT-I9506 using Tapatalk

[Cus]

How will you know what needs to be sorted if you don't roadtip for a thousand K's? haha

Eventually I'll be up your way, there's that guy that fabricates the things that make cars go faster up there, so we'll get to have our twinsies photo-shoot eventually

[Cus]

Hashtag "Farmlife"

I polished it before going on holidays. It lasted until about 200kms into the holiday. Then there was this driveway.... This is the "good bit"



Where I have mobile reception. Door are open because one of the dogs jumped in the car, and the seats were wet.....



[End Transmission]

[Cus]

I'm back! Let's start with some porn.

Bow-chicka-bow-wow, chicka-wow-wow-chicka.


That's the Snowy Mountain highway, heading from Tumut to Cooma, somewhere in the middle, about 5 minutes before you get into the really good stuff. As you can see, traffic was horrendous

So, I did "some" driving over the last few days....

[Enbiggen]

I came "in" on the Hume via Little Billabong, over the moauntains to Cooma. Excellent drive, and a great way to finish 7 hours on the road, by spending 2 in the mountains! By the time I hit the mountains it was raining, and the driveway to my Friend's house/farm/location 10 minutes out of Cooma almost saw me bogged. So much for polishing the car.... Cooma is cold, even in summer.


Monday I did the Comma -> Eden -> Cooma loop, purely because I've always wanted to go to Eden. Sadly, there were no talking snakes, and a surprising lack of apples...

(Maffra Road)
Lovely drive though! Definitely go "down" via Mt Darragh, the speed limit is 100 and there's not a whole lot of traffic. The "up" was via Candelo and then The Snowy Mountains Highway, there's more traffic and it drops to 60km/h in the good bits, which wasn't so bad, It turns out mountains + uphill + WOT + light bar = overheating. I had the tools with me to remove it, what I did forget to take however, was other bolts to hold the number plate on.... The Candelo run is bloody magnificent though!

(Candelo)

On the tuesday I swapped out the fuel filter I'd purchased but didn't have time to install prior to leaving. I had a lovely petrol aroma. There were no jack stands, or hoists, or even ramps, so I fashioned one out of a plank of wood and some stumps, and used the 1 foot dropoff at the edge of the driveway and my apparatus to get under the car. It wasn't nearly as dodgy as I just made it sound... I promise!

Thursday was Cooma -> Tumut -> Cooma. It was 10 degrees hotter in Tumut, and the kebab shop had no kebab meat, I was too afraid to visit the local pub, lest they also had no beer. The servo did have petrol though, so I left them and their crazy lifestyle choices behind.


Sunday was Cooma -> Jindabyne -> Geehi -> I dunno -> Not Sure -> Hume -> Home with the Victorian MX5 club.
(Dead horse Gap)

Somehow I managed to time a holiday to coincide with my local club being insterstate, and 45 minutes down the road from where I was.

They went to the Walwa pub for lunch, and I hit the Frog and Toad, driving home though a Dust Storm, and then an hour later, a normal Storm, before arriving home to basically the same weather that I had when I left (Hot and Sunny)


All up it was "only" 2000-ish km of travel, which makes it a short road trip by my standards But much, much more of the travel time was spent at altitude on the twisty corners, so it was far more action-per-kilometer!

And finally, my favorite shot of the car from the whole journey:

[Cus]

It's theory-crafting time!

I've been thinking. It's scary, but I've been doing it. I want to rebuild my motor (or another block+head then swap them in).

Not a spastic all-out build, just rods and pistons and some STM-inspired headwork. I've done some ebay-browsing, and have found forged rods and +0.5mm 9.4:1CR pistons for somewhere around the $1000 mark, which puts me in the ballpark of "pretty do-able" - but it'll be ebay quality.

Mostly I want to try my hand at building an engine, so using ebay el-cheapo parts makes the investment far more fault-tollerant in relation to a total failue, ie: I'm not potentially grenading a block with thousands of dollars of parts in it.

I know as we approach 10:1CR with boost, 98 becomes severely knock-llimited, so I'd have to be going for flex fuel, which does love boost and CR, once boosted I'd have 98 for most of the time, and E85 for special occasions (nowhere near here sells E85, and the car can hold on to a tank of fuel for up to a month these days, so letting it sit with 98 would be better from what I've read)

A thicker head gasket can help alleviate the issue to a certain extent, but I'm not going to count on that too much.

So, the question I've been mulling over in my mind: at which point does the CR with Boost start to bring the expected output of a 1.6 on 98 back down below what you'd get out of the stock rods?


Side note; Holy crap. some of those images in the previous post are huge. Sorry mobile users.

[StanTheMan]

Will this be a BP4w? Or a B6?
I've been reading about
high compression pistons,
rotational balancing.
Boring out to 2L

If you are going to rebuild. There is a NB8a motor for cheap on Facebook . I sooooo nearly got it.


Sorry just re read your post
B6 .....

[speed]

Good stuff!
Really looking forward to this diy build.
From what I understand, boosting on stock rods on 98 is not an issue. The issue is that boost is limited.
The CR may add to that. Believe I've read that you can run up to 14psi on stock rods with standard comp. If that's the case I suspect you'd be limited to somewhere between 10 to 12 pounds.
Forged rods on the other hand and you could really boost her up. My turbo would probably be useless above 16psi for efficiency reasons, so that's where I plan to cap it with forged rods.
E85 with forged rods and 10:1 comp should easy handle 16psi.

Hopefully a guru can chime in as I'd also like to know what the limits are (for obvious reasons) and learn the actual science behind the figures.

Sent from my old phone using crapatalk

[StanTheMan]

I think Miaturbo net would have a lot of your answers
But then again. Probably not B6 hate......

[Cus]

[wow, this turned out to be really long and rambly]

STM: MT.net really, really don't like the B6! If I showed up there and said "I'm building a B6" I'd probably get banned right off the internet (I have done a lot of reading over there, though!)

I'm staying with the B6 because as far as I can tell I could wind enough boost into a built B6 to make everything behind it a "consumable" if I really wanted to (and I don't) so the extra effort of going up to a BP would just be more expense only to hit the same limits, a BP will just do it earlier in the rev range. (I figure a stock B6 will be cheaper to buy because everyone wants a BP, and the internal parts are about the same price either way) .. the B6 head isn't great, but .. meh. Rebuilding my existing motor would be cheaper again, but I don't want to be completely sans-car while I do this either.

I *do* expect to need a 6-speed at some point in the car's future. Hopefully semi-distant...

If money was no object, it'd definitely be a stroked BP attached to an RX g/box, and whatever diff didn't evaporate. (Or an LFX swap) Sadly, money is an object...

Speed, from my understanding (limited to google searches, and I once read the first few chapter's of Corky Bell's "Maximum Boost"... ) You can put approximately 250ft/lbs of torque through a stock rod at stock redline. More RPM means less torque because the weight of the pistons swinging around on the end of the rods grows exponentially with RPM (or something along those lines). The actual amount of boost you need to hit that 250ft/lb number can vary, depending on what else isn't stock in the setup. For a completely stock car, I think you're correct with those boost numbers.

I think also the boost will be limited as CR rises. If you think of boost as a CR adder/multiplier, it kinda makes sense. (The following is not correct in reality, but I think correct in concept - it's how I'm visualising the situation at least)

The amount of power you make will be determined by how much of an explosion you can set off in the cylinder. More air and fuel means a bigger "explosion" (ie; boost), but also compressing a smaller mixture more will also yield a bigger "explosion"; so hypothetically:

If you're at 100kPa intake pressure (ie; WOT and N/A) with a 9:1 Compression Ratio, You'll make (invented number) 100ft/lb.
If you're at 133kPa intake pressure (ie; WOT and 5PSI) with a 9:1 Compression Ratio, You'll make (invented number) 133ft/lb. (33% more air/fuel to compress)
If you're at 100kPa intake pressure (ie; WOT and N/A) with a 12:1 Compression Ratio, You'll make (invented number) 133ft/lb. (air/fuel 33% more compressed)

I'm positive things don't scale like that, it's the vibe of the thing. Also; the event in a cylinder isn't an "explosion", it's just a really-really-fast, controlled, burn.

"More boost and less CR" is preferrable to "less boost and more CR", Higher CR causes the mixture to heat more in the cylinder (uncontrolled, unmeasureable), where as boost gets cooled down via the intercooler and the addition of extra fuel. So we'd be limiting the amount of "unknown heating" from CR (I'm sure it's actually calucable by someone smarter than me) in favor of pumping in more air of a known tempreature. But lower CR means a lazier motor out of boost.

So on 98 there will definitely be a point where too much CR will limit the amount of boost I can run because it will start pre-ignigting (pinging, knocking, perforating blocks, whatever you want to call it, ie; an actual explosion, not a controlled burn) because the mixture is getting too compressed/hot and igniting itself instead of waiting for the spark plug to do it. Under that point I should get a slightly snappier motor off-boost, and get into boost a wee bit quicker - but the limit of CR and boost will depend on lots of things (piston shape, chamber shape, intake temps, etc)

Forged rods and 9.4:1 CR pistons on fleabay seem like a decent enough compromise. More than stock power while off boost, and more than enough to make me consider using less throttle while on boost. I'm curious as to roughly where the scale would tip from "more CR = more power out of boost" to "Too much CR limiting boost below what the stock rods could handle anyway" on 98. I don't want to go anywhere near the tipping point, I just want to know where it is so I can stay away from it!

I'm pretty sure Dann has proven going to e85 with high compression makes the whole point moot, you just wind in boost until you see god. I'm still set on going with the EFR6258 turbo when the time comes, so having oodles of boost on tap won't be an issue, it'll be a matter of keeping it turned down far enough to not destroy everything it's attached to on e85, and picking a nice safe level to have it on 98 to avoid detonation.

If the experiment goes well and nothing explodes, I'll eventually rebuild the "other motor" to use better quality items, and push it a little bit harder, adjusting the forumla to reflect what I learn from this build.