ZX-Tex

iTrader: (15)

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

hustler

iTrader: (6)

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.

ZX-Tex

iTrader: (15)

That sounds like a good price.

patsmx5

iTrader: (16)

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.

M-Tuned

iTrader: (6)

Pm'ed

hustler

iTrader: (6)

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.

patsmx5

iTrader: (16)

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

ZX-Tex

iTrader: (15)

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.

NA6C-Guy

iTrader: (1)

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.

ZX-Tex

iTrader: (15)

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

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.

ZX-Tex

iTrader: (15)

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.

Braineack

iTrader: (62)

what's with these weakass NB rods?

NA6C-Guy

iTrader: (1)

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.

barryb

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

ZX-Tex

iTrader: (15)

Thanks Barry will do!

Merry Christmas Everyone

barryb

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

ZX-Tex

iTrader: (15)

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?

hustler

iTrader: (6)

whoa, barry is here.

Stephanie Turner

We use Duffin. They do a good job.
Stephanie

ZX-Tex

iTrader: (15)

Thanks Steph