Engine build time
 

So it looks like I will be building a motor soon for my '99. See my sig for what I have now. I have been reading up on the various build threads here and have the following basic plan in mind:

Goal: 250 RWHP (GT2560 at 13-15 psi). Daily driver
- Use the stock '99 head I have now, freshen it up.
- Belfab rods
- Either Belfab (Supertech) pistons or new stock pistons (possible ceramic coating). Stock compression ratio 9.5:1 either way. Overbored.
- Motor otherwise stock, bored/polished/inspected/freshened where needed.

Questions:
1. I have been seeing here and in some m.n posts people are getting Belfab stuff for less than the price they list on their web site. What is the hookup?
2. For the stock parts (pistons, bearings, gaskets) is Rosenthal still the way to go for mail order?
3. Any suggestions for stock quality or better part sources is appreciated. For example, I do not need to use a Mazda gasket set per se if there is a proven aftermarket gasket set for less $$. I can get stuff at a significant discount from NAPA for example.

Thanks

you should go for a ride in my car. The blue print and balance is awesome...the motor spins soooo smoothly. You know what I gave for rods and pistons. The blue print / balance, bore & hone, valve-job, bearings throughout, and assembly was $1200.

That sounds like a good price.

FWIW for your power goal common wisdom says you don't need aftermarket rods or pistons. Why are you building an engine in the first place? Just looking for peace of mind I suppose? Either way, that's the parts I'd buy if I did it. Also, I'd use mazda engine gasket set and put a new TB/WP/idler/tensioner and new oil pump.

Pm'ed

because his block is showing off some rods. The mazda brand gasket set is a good idea, but my Oreilly bought gaskets all worked fine.

lol. Yeah, that's a good reason. :giggle: I bought a gasket set from neo and it's some cheap brand shit. Not too impressed with them. They probably work fine, but the quality is definately not the same as Mazda or Felpro.

Yes long story short the motor blew up on the way to work this morning. Here is a picture of what is left of the #4 connecting rod as viewed through the hole in the left side of the block. The outline of the I-beam portion of the rod is visible; it snapped off right where the rod transitions into the crank bearing end.

Ouch. I would go for the Belfab rods and stock pistons. Id say stock rods, but Id guess Belfab are probably cheaper anyway, and lighter. Your goals sound about like mine. Im starting at 160-180 but eventually hope to see the 220-240whp range on either a 2554 or 2560 (probably the later of the 2). Plan on doing this as a side project, or quickly to get it back on the road? Mine started in a rush to get it back on the road, and turned into a 4 months nightmare. Im just now about to start assembly tomarrow or wednesday. Hope yours goes smoother than mine.

I think what happened here was a case of open-loop EBC overboost due to cold temperatures. I had just retuned the EBC to raise the boost from 12 psi to 14 psi. On the morning when this happened the air temperatures were about 20 deg F cooler than when I retuned the EBC. I had pulled out into traffic from a stop and had to accelerate hard to avoid a truck coming at me fast over a blind hill. I accelerated in first (part throttle), second (WOT), then boom, rattle, smoke...

The overboost protection was set at 224 kpa (about 18 psi). It did not kick in. There was no detonation and based on my past logs the AFR was fine, 12:1 or richer. So I think it probably overboosted to 15-16 psi and it was too much for the motor. I do not know for sure since I was watching traffic (not the boost gauge) and I was not data logging at the time.

The ironic thing is I was scheduled this morning for some dyno time with Tim at BEGI to do some fine tuning :crx:

So basically my philosophy is that if I am going to build a motor I want a little extra insurance that this will not happen again. I agree from what I have read that the general consensus is that stock rods and pistons are OK for 15 psi. But if I am going to all of this trouble to build a new short block, then I'll spend a little extra and strengthen the bottom end. I can afford it as long as I do not get stupid (like titanium rods) so why not.

On a tragically amusing note, I found this piece of debris in the road where the engine let go. From the size and wear markings it looks to me just like a wrist pin though I do not know if it is Miata size or not. It is about 2.25" long and 0.75" in diameter. I know the piston is broken, but if the wrist pin made it out of the block, holy crap...

Oh yeah fortunately I do not have to do this in a hurry as I have another vehicle I can drive in the mean time. My main motivator is I want to get it running again soon as I enjoy the hell out of driving this car. I have it set up nicely and it was running and handling great right up until the engine went bang.

I have checked Rosenthal Mazda and a local Mazda dealer that gives a discount to employees of where I work. Best so far is $60 a piece for .025 over pistons (with pins and clips) and $120 a piece for rods. That is $720 a set without rings. Damn. At those prices I might as well spend a little extra and get the Belfab stuff.

what's with these weakass NB rods?

After rings and bearings,thats like $900. Might as well go Belfab like you said. Wouldnt be that much more, if not less. I kind of wish I had gotten Belfab rods now, but I think I will chance it with stockers.

Man, that sucks!

I tell anyone boosting a 99 or later engine (NB) to replace the rods with aftermarket versions. It's hard to remember that engine version was released almost a decade ago but a large number of the guys on the MiataPower list discovered the hard way that anything over 12 psi (on the old FM2 equivalents) eventually resulted in a ventilated block. That's the reason I put aftermarket rods in my engine even though it only had 231 miles on it.

If you start to suffer boost withdrawal symptoms, give me a call and I'll bring my car by for you to drive....

I have an engine hoist and engine stand if you need to borrow them. I can drop them off with my pickup at your office. And, if I have some spare time, I'll be happy to give you a hand swapping the engines. I've done enough of them I've made most of the mistakes....

If interested, just contact me at my southwest div 15 email address. I check the email a few times a week.

Barry

Thanks Barry will do!

Merry Christmas Everyone

I forgot to mention I also have the factory shop manual for the NB engine. It's good for everything but the accessories on the engine; very handy for those pesky torque values. Be sure you have a freshly calibrated torque wrench or a really good engine assembly shop. If you have to get engine work or have parts balanced, I'd recommend Duffin's up by the airport.

Cheers!
Barry

Yeah funny you mention them I was planning on using Duffin. They worked on a Honda motor for me many moons ago (before Hondas were cool) and did a good job at a good price. They did the machining, rebuilt the head, and I did the final long block assy. For this I may just have them do the whole long block build though to save time.

I had heard from another Miata guy in SA that maybe Duffin was not a good bet. Do you know of anyone who has used them recently with good success?

Also I will be looking locally for a short block or a bare block (assuming the crank is still OK). Know of any?

whoa, barry is here. :)

We use Duffin. They do a good job.
Stephanie

Thanks Steph

That really sucks...but a good excuse to upgrade! I have an 03 long block...with 30k miles...but it's too nice to rebuild. I would assume anyway....

BTW, duffins did the balancing on my race engine for the Cobra...I'll let you know how it goes in another week or two...

A few people have asked for the MSQ I was running when the engine blew so I will post it here for whoever wants to see it.

So tearing down the engine today I discovered a lot of oil in the intake manifold. This is not the usual PVC blow-by accumulation, but small pools of engine oil in the intake manifold. There was also some in the passages of the throttle body (not the coolant circuit). I discovered it when I pulled off the throttle body and all of this motor oil came dripping out. It was definitely a WTF moment. The oil is all downstream of the throttle. The rest of the intake plumbing, including the IC, is spotless.

The #4 plug was soaked with oil when I removed it.

So I am thinking one of two things happened here:
1. If the piston is broken, it leaked a LOT of oil into the cylinder, which was then sprayed into the intake when the valve opened. The engine rotated a few times of course after it blew (before I could shut it off and put it in neutral).
2. A blown head gasket leaked oil into the cylinder. This could have in fact precipitated the failure. But, there is NO coolant in the oil and NO oil in the coolant. I checked them both when I drained the fluids from the engine. The coolant looks fantastic in fact.

Hmmm. Thats kind of odd. Wouldnt think it could get that far up the intake after the engine went.

Here are some pictures of what I am talking about. The dark pools under the VICS butterflies are pools of oil. It did not look like this the last time I had the upper intake manifold off. In fact, none of this stuff looked like this.

Very strange. Could have cracked a piston from detonation, and that lead to a large amount of blow by. But I don't think that would result in "pools" of oil. Like you said in #1, it was probably an after-event of blowing the engine.

I hope you find the "cause" of this failure. You have me worried.

Is that metal debris in the pictures? If so, it's about gotta be #1.

Yes that is metal flakes in the pictures of the throttle body and the intake manifold next to the throttle body.
The #1 spark plug looked fine. The #4 plug is the one with all the oil on it.

I just ordered the full engine kit from Belfab, which from what I can tell is a good deal with the sale they are having. This should make for a nice motor.
BELFAB RACING PRODUCTS

By the way, their web site is a bit messed up according to the owner at Belfab. The Supertech pistons are available in a 9.0:1 compression ratio, at least in the 1.8L. Also, according to the owner, there are only two of these Miata kits left, so if you want one...

the email I recieved from James Bel:

Yes I thought I might have to play that game if all they had was the 8.5:1 as indicated on their web site. Either that or get 9.5:1. What compr ratios are available on their site depends on what link you click, which is confusing.

So I called them and asked what they had. They have actual 9.0:1 pistons which they added more recently to cater to the moderate boost turbo crowd. According to the owner the webmaster has not updated the link yet. So apparently they come (or in past and present collectively) in 8.5:1, 9.0:1, 9.5:1, and 11.0:1.

well fuck me running. It sucks to know my car could be substantially better, but its pretty strong with the 8.5:1 pistons off boost.

That Belfab kit looks like a great deal. I wish you could get it without the gasket set and bearings and ring.

i had some fitment issues with the gasket kit, and they sent me an escort water pump. I could have sent it back and scored the right stuff, but didn't have time for that when the motor was sitting at the machine shop.

Also, how can you order bearings before you have the motor yanked apart and everything measured?

Good question. There is a good chance the crank will still want the standard bearings. If not, I can swap them out with what I need, no charge. The motor is at the machine shop now so I'll know soon anyway.

If that is what you want, maybe you can. Call them up and see if you can work a deal.

Update:
Turns out the donor short block I had to replace the one above had a bad crank in it due to a badly spun bearing. So, the engine shown above will be coming out next weekend and hopefully its crank and head :x: are still good. That way all I need from the donor short block is the block itself.

ARP main bearing and head studs are ordered.