aaronc7's Turbo Miata Build

[Neverlift]

Your diff is next. Might as well get one now.

[aaronc7]

Originally Posted by Touge Sensei Your diff is next. Might as well get one now.

Why the diff? T2 Torsens are pretty strong jah? It's 3.9 ratio too, so should be good to go with the 6 speed. I'll only get a 3.63 if I see a killer deal, but they seem to be getting more and more rare- driving value up.

[bigx5murf]

Any idea what final drive in the 6spds? Most likely 3.9, I'm contemplating swapping my 4.1 for 3.9s

[aaronc7]

Originally Posted by bigx5murf Any idea what final drive in the 6spds? Most likely 3.9, I'm contemplating swapping my 4.1 for 3.9s

Flyin' Miata : Technical info : Gearing calculator

3.9 swap would probably be a little better if you're pushing a good bit more than stock power...but would probably be a pretty expensive swap for not much gain. I guess you could sell your 4.1 and probably come out about even in the end, though.

3.63 rear end would be sweet!

[Neverlift]

You need north of 250 to even make use of the 3.63. So in Aarons case it would be nice.

OSGieken would be a direct replacement for the MSM rear diff with the thicker/stronger half shafts and driveshaft.

The 6 speed is almost identical in FD as the 5 speed.

[bigx5murf]

Yea, I'm so torn on gearing, 3.9 would be so much better for me right now, especially once I get tuned and raise my redline. But down the line 3.63 is better, but it'll make me accelerate like a dog right now.

Yea, OS giken is :drool: supposedly they're indestructible too... so pricey tho...

[kilik2]

Aaron just get the ford 8.8.

[aaronc7]

350 or whatever 22psi ish gives me is all I'm going for. Stock torse should be fine. Some of those lower ratios offered in the ford 8.8 would be cool though. Eh, too much work, lol.

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[aaronc7]

Plan right now is to pull the motor, drop it off at a shop before I head out for awhile. Order parts over the next month or so, and have them do all the work there. Hopefully when I get back, I will haz completed built motor. Still need to find a 6 speed, deal fell thru with the one guy in ATL, oh well.

[Easter Bunny]

I don't see the problem with that transmission you have four more gears just ride the clutch a little in third it will be fine lol

[aaronc7]

Motor and trans almost ready to be pulled. Borrowing friends hoist tomorrow. If its not out tomorrow, then friday for sure. Quick teardown then its off to shop.

Still looking for a 6 speed.



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[Cataphract_40]

Sorry to hear about the car woes Aaron.

Fuckin trannies. At least it was the tranny doing the blowing and not you. It will make a good story. "So there I was...

[Ferg]

build looks amazing. but how much did it all cost?

[aaronc7]

i was good about keeping a total going back in the day, but now i've changed setups etc I really havent kept track. It was around 10k before, including rollbar, suspension, turbo stuff, ecu, EVERYTHING. More than that now since I got a new turbo, and ewg, but counting the cost of the car and after motor build, i'd say around 20k total in it.... which wont be bad for a 350whp+ 2300lb car.

Motor is out... taken apart for the most part (machine shop asked for engine to be assembled still). Off to shop it goes today hopefully.

[aaronc7]

Guy still hasn't gotten to my motor I don't think for teardown/machien work etc... but in the meantime I've been planning some side projects as well.

Honda intake manifold. Plan now is to take a godspeed Honda B18 manifold (skunk2 knockoff), cut stock intake manifold @ flange, and weld the two together. Use stock B18 TB for now, but tons of aftermarket options there.

A few have done it before, one guy with a GT2871 @ only 14psi, saw around 30HP peak gain, with largest delta closer to 45HP at redline....no power loss above 4k (where turbo hit pull boost)

Thought about going custom route....but it would be totally untested, and cost a lot more, and probably stuck with stock TB (55mm), unless I went aftermarket which would have drove the price even more up.... Value wise, hondafold seems to be the no brainer.

[aaronc7]

Next on my to do list is the "Exhintake Cam" swap. Basically it's putting another exhaust cam in place of the factory intake one. I'm still researching and learning about all this cam business, but seems to be pretty legit. Exhaust cam has a little longer duration and lift... my concern is the increase in overlap, which I've read you don't want too much for turbo application...but looking at Evo cams etc, I think it will just fine, actually very comparable to popular, more mild, 'street' evo cams. It's a rather popular mod for the NA miatas (different cam specs), not many have done it for the NB/99-00..... so we'll see.

For those interested, or able to offer advice, here's the specs:

BP ExhIntake Cam Swap | DIYMiata.net

Here's the site I compared Evo cams with:

Cam Specs - Hard numbers, really!(sticky, no replys) - evolutionm.net

Particularly I was comparing to the HKS 264 and 272 cams, because I had seen dyno comparisons with those involved... Duration wise, the 272s are about the same as the stock exhaust cams, evos having a bit more lift, but can't really get much more on the BP motor, so not really paying attention to that.

Interestingly enough, the Mazdaspeed Miata comes with an entirely different intake cam, which has .349" lift, and a tiny bit shorter duration than stock 99-00 intake. FM did a dyno comparison though (turbo), and the 99-00 actually spooled a few hundred RPM sooner and up top power was identical, even a slight nod towards the 99-00, interestingly enough. They concluded maybe there was other reasoning behind them using that cam (emissions? rather than performance).

[Neverlift]

Learned something new about the msm. Thank Eryn

[aaronc7]

Found and paid for 6 speed, 72k miles. Also bought.... VEI oil temp/pressure gauge/senders, EGT probe and misc electronics to make it loggeable in ECU, some resistors needed to make the stock water temp gauge linear, new MAP sensor for MS (44psi bitches!!). Attempting to track down idler pulley, so I can depower my steering rack and keep A/C.

[aaronc7]

Well, engine is tore down. Just need to make final decision on which compression ratio pistons I want, and engine bearings, and I'll be purchasing all the parts and hopefully getting it all together here soon.

130k miles on motor. Some of the rod bearings were a bit questionable, possible spun rod bearing not too far down the road he thought. One of the intake shims was crooked, not really sure how that happened, if it had been rebuilt before incorrectly or loose spring was just letting it jump around.

But big picture crank and everything is good to go for rebuild.

As for bearings... I feel ACL Race series may be a bit too hard for my use, and wear too easily and quickly. Want something stronger than oem or oem equivalent, trying to pick something that's a good middle ground.

As for compression ratio, choices are 8.6, 9, or 9.5. Was thinking 9.0 as a good middle ground/all around build. But my new intake cam will lower my dynamic compression ratio, so I might bump it up to 9.5 to make up the difference. Thoughts?

[aaronc7]

8.6 pistons it is. now just to finalize bearings. anyone have experience with ACL Duraglide? no homo

[dubunderpar]

How have I never seen this thread. This Almost makes me want a miata, almost.

[aaronc7]

Originally Posted by dubunderpar How have I never seen this thread. This Almost makes me want a miata, almost.

once you drive a few....you will. trust me.

[dubunderpar]

There is a turbo'd one around here for sale.....hmmm I think my wife would literally kill me.

[Neverlift]

Miata must have a turbo or it is just not worth owning.

[cpolly69]

Originally Posted by Tony says: Miata must have a turbo or it is just not worth owning.

don't you have a miata without a turbo?

[aaronc7]

Don't you both?

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[Neverlift]

Originally Posted by cpolly69 don't you have a miata without a turbo?

For sale

[Lex]

A little late here but for a turbo car you want compression ratio on the low side since you can more than make up for it with boost. I would have gone with 9 - that's what I went with on my BP build - but I had 8.2:1 before that (GTX motor) and it was perfectly fine.

[aaronc7]

My setup and goals with pump gas (don't want to run meth) I'll be knock limited even with the 8.6 pistons so that's why I picked them. It will give me the largest margin of error in tuning. Not only make it easier for myself but I don't have any sort of advanced knock control system...it just makes the most sense.

With that said though, I will definitely want to spark tune the car to get the most of it. Which I plan to do once most of the tuning is done and big bugs worked out in general. I have a device that you hook a clamp onto the side of the engine block and listen with headphones for engine knock and tune that way....either on dyno or with passenger in the car on the street. Find where it starts to knock, back it off a bit, and done.

[Lex]

Good ol det can method. I've always wanted to build a proper knock sensing system for the MS because it lacks it in a big way.

[cpolly69]

Originally Posted by Lex Good ol det can method. I've always wanted to build a proper knock sensing system for the MS because it lacks it in a big way.

don't the 99-05 cars have knock sensor?
i'm pretty sure that was one of the revisions in (dimitris) revrant's latest enhanced ms2 that he builds over on mt
line 8 here
Enhanced Megasquirt Group Buy for all Miatas (90-05) - Miata Turbo Forum - Home to the Turbo Miata

[aaronc7]

Originally Posted by Lex Good ol det can method. I've always wanted to build a proper knock sensing system for the MS because it lacks it in a big way.

Their new MSPNP2 they are starting to include some knock stuff (I think). Reverant on miata turbo and MSextra has some sort of knock circuit included in his units now too. But yeah, I have neither of those so it's pretty much my ears is all I have!

[Lex]

The knock sensor stuff that used to be around was not great .... not sure if they are better but a fine tuned knock sensing circuit was sorely needed in the past.

[bigx5murf]

I think this is the knock sensor

[aaronc7]

Yeah, there is a knock sensor. The issue is filtering the raw input signal to make it something that's actually useful/accurate. There's been a lot of work lately into this area, and I suspect MS3 will get some good knock features here before long, but either way I don't have it to rely on. But with a conservative tune, low CR pistons, all this stuff, it's really not a big deal IMO. These MZR motors on here have high DCR for a boosted motor, so they tend to be pretty knocky, and this knock protection stuff becomes very important.

[aaronc7]

fmhimn

[Neverlift]

Kettlebrock or Junk2?

Shits nice.

[aaronc7]

lol

Godspeed. Skunk2 knockoff,, just like blox pretty much, except cheaper.

[Neverlift]

Awesome. This is gonna be nuts. I am kinda jealous.

[Cataphract_40]

Here's an update on aaron's turbo miata build for you all:

2JZ miata swapped / conversion. single turbo - YouTube

2JZ miata swapped / conversion. single turbo - YouTube