mr2nique

I am a fairly new board member, so please excuse the noob lack of knowledge. I am in a bit of dire straits, so thank you for the help.
Years ago I had a '99 NB1 with a Flyin Miata Turbo kit. All FM no other engine mods.
I moved that to a newer '03 NB2 Miata and decided to go "bigger" with this kit and do a standalone MS MS3PNP ECU and Deautchwerks 550cc injectors.

After the install was complete I had a local tuner who says he has tons of miata and megasquirt experience do a dyno tune. He spent 2.5 hours on it and it ran 226whp 201 wtq.
He had me at 15psi at low rpm and then 11.5 to 12psi at high rpm.

Well...within 2 days I bent a rod or two.

A) I am thinking of finding a lower mileage replacement NB2 motor and either set the PSI to 11-12PSI for the whole range OR downgrade to the Flyin Miata piggyback (8psi) as I had NO issues with that and it was much much less a PITA.

B) Other thoughts on where to go from here?

*) Do you think it was the fact I was at 15psi (even at low RPM), a terrible tune, or that my motor was 105,000 miles and maybe in bad shape (used car is newer to me) or any million other reasons? [I can try to later share my VE table or other if that would help]

1) Any suggestions on finding a replacement motor?


I am in a terrible painful place as it was so much work to get here for it to last all of 2 days. :(

Thanks in advance for any help and ideas.

HarryB

If your block is not ventilated yet, open it up and see what's the status. I have seen a few being able to just swap rods to a forged set and call it a day.

Dr.Sep

that sucks!! So my initial thoughts reading that -- don't give up your MS to go piggyback, that is a huge step backwards. If I was trying to keep a stock block alive, I would have ramped boost in going higher as rpm rises not lower. Hitting 15psi down low probably was too much torque (this is the rod bender). Like, 10psi until 4k and then ramp it in. Its not the HP that kills them (within reason) its that torque, and the tune you described sounds like it just smacked those rods with low down torque and bent them, and then softened as rpms rise which is really the opposite of what you want with a stock block bp

Full_Tilt_Boogie

iTrader: (1)

Know how I know your tuner sucks?

But yes, post tune.

You could take this opportunity to throw some rods in the block, leaving all else the same. Or go the extra step and do pistons as well.
Either that, or find a junk yard engine to toss in there. Theres no reason it shouldnt be able to make more than the 226hp you were making, without failing. The tuning just needs to be right, and there are ppl here that can help with that.

borka

iTrader: (1)

Rods bend with high low-mid range torque. Your tuner did the exact opposite of what the tune should be.
With stock rods you want to start off with about 10psi and ramp it to 12psi by recline for a nice safe progressive power curve, with about 230hp.

Gee Emm

Either way, that engine is coming out, right?! I'd have a look at the state of the crank journals, and whether there is any damage inside the engine that would rule out a 'rods only' rebuild. If it all ok for a rebuild, look at your budget, and either throw a set of chinarods, in, or add some pistons too. If you plan on reusing your pistons, have a VERY close look at them for any signs of detonation.

Throwing a junkyard engine in is a quick solution, but limiting as it will have 'those' bendable rods still. A good tune will keep you safe, but obviously at lower power than with better rods. When you want more power, it will be back to pulling the engine and doing the rods (at least).

mr2nique

You all are amazing for these replies.

For some context: I am a 3 out of 10 on a wrench at best. For example, the turbo install was done by my shop, not me.
I think I am leaning towards the simpler solutions as I can't swing doing an engine rebuild myself and worry about the cost implications of working with an engine builder here (or the long-term reliability of a non-oem built motor).

My current thought is to go for a used 1.8 VVT with lowish mileage, then lower the turbo to no more than 10 psi (and maybe ramped to 12psi closer to redline as Borka suggests).

As attractive as forged rods and maybe better pistons sound (mmmm power), I see the beginning of a never-ending money pit for someone who can't/won't do much of the labor. (I just glanced at youtube and see someone installing new rods....nope, That's not me or my wallet at the moment.)


The good news is:
A very talented mechanical inclined close friend did offer to maybe lend his hand for a week to help pull/install the replacement motor, so maybe I won't be fully in the hole for money. It also sounds fun. I like working on cars, I just am kinda crappy at it. I am way better at car detailing.

Does anyone have solid suggestions on where to source a lowish mileage, reliable OEM 1.8 VVT?

Thank you so much.

SpartanSV

How did you determine a rod is bent?

curly

iTrader: (25)

I had a weird noise in my motor a while ago on the way home, borrowed a truck/trailer, drove it to my work, and ~48 hours later I was holding the rod bearings in my hands.

That's not typical for everyone.

However, rods are really cheap, and if your current ones are bent, it doesn't necessarily mean the engine is bad. If you're looking for a spare engine, I would look for any 1.8, preferably one from a NA for the pistons. Put some forged rods in it, fresh OEM bearings and rings, then after pulling your current engine, refresh the head and slap it on your forged engine.

OEM pistons don't get enough credit, they're plenty good to power levels that'll scare most people.

What's your location? We might be able to refer you to reliable machine shop/engine builders with that info.

ridethecliche

iTrader: (2)

I mean... If I could learn to work on a miata with the help of this forum and friends along the way........

allofit

I feel your pain. Sucks when our cars implode given the time/effort/money we pour into them.

How did you determine the rods are bent? Only asking because I thought I'd bent my rods and it turned out the timing belt had slipped a tooth.

We need to see the tune but I agree with everyone... your tuner did it the wrong way around. I'm running 10psi at low rpm ramping up to 14psi at redline with a Borg Warner EFR 6258 on a totally stock untouched 1.8 VVT engine. 2000 miles so far and my car does lots of WOT redline pulls every time I take it out.

What's your location? I'm in the UK and could possibly help you source a good VVT engine pretty easily. I'm tearing one down right now to put forged rods/pistons in it so I can crank my EFR.

Think about your power goals. If you'll be satisfied with a 220hp miata (hint, you won't!), and you have the help of a mechanically inclined friend, then drop another VVT engine in the car and don't look back. It'll be a great learning experience and with a good tune your rods will be happy all day long at 200wtq.

If however you suspect you might want more than 220hp (hint, you will!), now is a great opportunity to throw some ebay forged rods in your block and max out your FM turbo, presumably a GT2560? Stock pistons are safe and reliable at 300hp in the absence of detonation.

HarryB

In the greater scheme of things, forged internals will lead to more boost, thus to more power/torque, thus more expenses on the driveline (5-speed gearbox can take only so much, if you already have a 6-speed discard my comment).

mr2nique

I can't say this enough, you all are some amazing people. I didn't expect this much support. I wish I came earlier BEFORE I starting building this and BEFORE I went to a tuner. Many years ago I was huge into MR2s (had a 300hp mr2 turbo with 10 years of love into it) and the forum people were great. I have not got much forum experiences since the years into Miatas. The few times I dipped tows in some forums, I got some negative pushback. Thanks for welcoming me.

Some answers and some questions:

Why do I think I bent a rod:
I am not 100% sure either. The racing mechanic shop I took it to doesn't only do miatas, but he does a lot of miatas. He is very bright and kind. I towed it to him and asked if he could diagnose it. What he told me was that he got it cranked and shut if off within 20-30 seconds and strongly feels "do not run this motor". He had another Turbo'd Miata come before with known bent rod(s) and they tried to use the semi-broken motor to limp it into the garage bay, only to have the piston/rod break through the block causing even more expensive destruction.

He felt the noise sounded just like the other car with bent rod(s). It is hard to get cranked and behaves strangely.

Could it be something else...maybe? Not sure how to diagnose 100% without tearing it apart and limit cranking of the motor as much as possible.

What to do about the tuner:
The tuner I dropped $$ with already knows I had a catastrophic issue, but is not yet aware we think it is a bent rod. I am still unsure how to approach him. That's a whole another thing. The car started overheating on the drive home, on the freeway (it never had any cooling issues) it never had any cooling issue and he knows that too (never got above 240F, but I had to stop and then take side roads. My other friend thinks that may have been the torque pushing my head gasket?)

What to do next:

1. The block needs to be pulled out for sure.
2. Some other block needs to be purchased (to my understanding this level of damage causes contamination and likely damage to the cylinder walls, among other things)
3. Then there is the decision of replacing the rods (and possibly the pistons) with something forged while the motor is out or keeping it OEM sealed.

• If Unopened block -> Follow the advice above to keep power in safe zones
• If Forged internals-> Much more power, even from a GT2560 smaller turbo

1. Then install and adjust tuning very effing carefully

I just dropped $$$ and lots of money on a car that sat in the garage waiting for all this, so I again stopping for a moment while I figure all this out and see what free/cheap resources I can utilize, maybe a friend in Sept to help with the install. This is all too much.

Questions

1. What is the proper way for me to share my tune? Screenshots of the VE table and other things? Actual File??
2. I am Washington State, Americas. Anyone have suggestions for Engine sources, ideally, that are tested (other than the junkyard inventory https://www.car-part.com/ which likely don't test)
3. I am in Washington State, if I do go the forged path, any idea who can do this?

curly

iTrader: (25)

You can attach the full .msq in a thread.

Who was your tuner? I'm down in the Portland area, bring all my cars to Kris at KO Racing for his dyno, who you may know from your MR2 history. I've tuned a few dozen miatas there, local and not. I do know of a built engine that's for sale by a friend, PM me if you'd like some details, it's a BP4W though. Otherwise you can get a hold of Freddie (?) who imports them at a good price from the UK.

mr2nique

Here is the tune. What do you guys think?

I know Kris (KO Racing) a little bit from my MR2 days. Sadly I spoke with him and was ready to take it over to him but the car was not quite driveable after the injector install so I ended up towing it to a more local shop. I'll hold my mention of who for now until I speak with him more.
I wish I would have gone with Kris though, I think I wouldn't be in this situation if I did.

Gee Emm

Other than inspection of the rod poking out of the hole in the block (an option not yet available to you, hopefully never), the usual way is a clicking sound as the rod touches the bottom of the cylinder each time the crank rotates. Mild bends are pretty undetectable until teardown (usually when putting stronger rods in, resulting in a big sigh that says 'just in time!'), but they will bend further in time with the use/load they are seeing. Ignore the clicking, and it just gets worse/breaks, So, push/trailer it wherever it goes until that one comes out.

In your case it probably came on quickly, given the elapsed time between tune and diagnosis, so hopefully no further damage to bores. If the bores are good, and the crank is in spec and no cracks, it is probably a rebuild proposition, but only a teardown and inspection will tell.

Mr Plow

My NA VVT made peak torque at 5000rpm - I'd ramp boost in after that if you're going to do it and want to be uber safe. e.g. at 5,500rpm. I do this on my turbo setup. Yet to dyno but have done logged runs of mph/sec and rpm/sec to see the trend in acceleration (closely related to torque). Ramping in after 5000 maintains a flat accel log. Anything before would create a peak which will also be a peak in torque which I'm aiming to avoid.

This forum is an ace resource of people's experiece - we are spoiled for data.

Good luck on getting sorted as easy as possible and turn your 3/10 into an 8/10 on the wrenches with patience (says someone still learning patience! haha).

curly

iTrader: (25)

I would say your tune is 5-8ish degrees too advanced, however I tune conservatively.

Also you have boost cut at 205kpa, with a 10kpa hystersis. So it'll start to cut boost at 195. 15psi for reference, is 203kpa. So either you're not actually hitting 15psi, or you're hitting boost cut a lot, which can damage rods, since it typically happens at peak torque.

DNMakinson

iTrader: (3)

Open loop EBC as well.

I don’t think particularly advanced in the high boost 3-5k rpm, but 2k seems a bit advanced, as does 100kPa row.

It does seem that just too much boost, assuming base timing was correctly set.

AFR targets and 70kPa and up VE table look to be shaped well.

gesso

iTrader: (1)

You can pull the plugs and turn the motor over by hand.
Then use a dowel in the spark plugs hole to mark the top dead center height.
It's unlikely that they are all bent, and therefore you would be able to see a height difference across the cylinders.

But if it's busted enough to sound bad... Well it doesn't really matter if you diagnose bent rods in the car or out.