Did you do a wet compression test to see if it's rings or top end causing the real low #3 numbers? It's strange that all the numbers are that much lower. Will be interesting to see what the headgasket looks like.

 

In my experience, loosing 20 PSI that quickly but it runs fine = bent stock rods. The cylinder that's way down, dunno, you'll have to take it apart/pull the head. Or do a leakdown test.

 

I just looked back through your post, but didn't find details on what happened. What happened when it died? Overheat, under boost, normal cruise? It's been freakin hot here.
Did you drain the oil yet? Would be interesting if there is debris on the oil filter or bottom of the pan.

 

Well I was driving home from the bar...

I just pulled up to a stop sign and noticed the noise. Drove the rest of the way home just staying out of boost, the noise still pretty obvious. Car didn't feel any different, but again, I shifted at like 3k in each gear.

EDIT: I haven't drained the oil yet. Probably tomorrow.

 

I've had a few people recommend I throw rods in this new motor. My biggest explanation for not doing this is cost. If I put rods in, I might as well do pistons while I'm in there. So then you're at $900 in parts. Add $400 in bearings, gaskets, etc. Add $400 in machine work. Add other **** I'll have to buy, and you're at $2000. I don't see doing "just rods" costing me less than $1000 at that, once you factor in virtually the same parts and machine work required minus the price of the new pistons. It just isn't in the budget right now. And moreover, I don't want to dump a ton of money into a car I'm still not convinced I will own in three years. So unless someone has a built bottom end they want to offer me a tremendous deal, this motor is getting plopped in as is. I only plan on replacing the rear main, oil pan gasket, and valve cover gasket.

I think I am going to run E85 from here on out, as I suspect once I break this down I will find evidence of det. If I don't, then I guess I'll just be being proactive. But the relatively small investment to switch fuel types seems worth it... I guess. lol

 

Were you driving it hard before this?

Hopefully you were at the bar at night! I was wondering if it happened in the daytime. I have been seeing coolant temps around 220 with AC on, even higher before I did all the radiator ducting. Any white, blue, black smoke when you start/run it?

It will be interesting to see what failed. Listening to the vid again, I have heard similar noises when a lifter collapses, but you don't have HLA's so it can't be the case. The pick of the top end looks good. No shiny bits of metal and appears that the shims are in place (can't realy tell on the valves that are open).

 

The motor saw 225-227 frequently driving home from work, but when the coolant warning like cut on at 225 I would always turn the A/C off so they could fall back down.

It was quite cool out, and yes, there may have been some flat shift straight aways. I did not notice any smoke when I restarted it.

It is also worth clarifying, whilst doing the compression test, you CANNOT here the same noise. My most recently suspicion was a rod had bent and was hitting the cylinder wall. But, I feel that this disproves that possibility.

EDIT: It is also (also) worth adding, that we had JUST changed the boost a little bit. I modified the wastegate bracket, and it held the boost level much better. However, it spiked more. It would spike to ~14-14.5psi and fall to and hold 12. Everything I'd read had made me decide 225ft-lb should be safe, but alas I am tempted to say it is not. She was a young motor, just crossed 80k I don't think we're going to run over 200ft-lb anymore. Which is honestly a noticeably depression in how fun the car is.

 

I have a built bottom end that I might be willing to sell/trade (ref. my build thread for details) and I'm sort of local. I'll send you a PM.

 

No you need to finish your car and put on the EFR.

 

NEVER!!!!

 

225 lb ft should be safe, but there are no guarantees! Variations in the tune, fuel quality, driving style, and the engine itself make a difference in how long it'll last!

Remember that the VVT engine has higher compression and it will be harder to run the same boost on pump with it.

 

You can do rods only and use stock pistons. I've done that many times, and ran lots of boost. Stock pistons break around 350whp in my experience.

Let me tell you how cheap I've done this.

Ebay rods
Reuse stock pistons
Reuse stock bearings
AKA only new parts = ebay rods
New ebay gaskets
Cheap fluids
30 dollar hone, hone cylinders
Bought 100 dollar set of rings
All assembly done by me
Very cheap.

 

Shhhh don't discourage him.

 

Cutting a (I would say) big corner on rings going with DNJ at $32 vs. Mazda at $142 shipped on MazdaMotorsports, this is the cheapest I've been able to add things up to be. It also features a DNJ gasket kit, and zero (ZERO) professional machine work. All and all, I would call this a bad idea. But, curious to hear any input. I'm really not comfortable reusing the bearings since I'm in there, and ACL is only like $45, so. Luke used these gaskets on his motor, but it's never been started to verify it worked. He also bailed on the flex hone, DNJ rings, and stock pistons, took the block to the shop, and got his head cleaned/machined. Sooooo.

 

Well you do have a spare engine...

 

I would be careful with the real cheap chinese gaskets. I got a set for about $100 off ebay when I rebuilt my 1.8. All the critical seals were leaking within the first year. I have since replaced front/rear main seals, cam seals and valve cover gasket (got MR special o-rings for CAS and oil pump). I have since replaced all these items with Felpro gaskets and no leaks yet.

 

I have had hit or miss results with the cheap eBay gaskets. For cam and crank seals I will only use OEM from now on. For all others I have seen both types leak.

 

My thoughts:
Use high quality rings. Cost sucks but these are important. I found good ones for 100 when I did it.

A while back you could buy an entire ebay gasket set for 40 dollars shipped. I ran that, but bought a Felpro head gasket for 60-70 dollars to be safe.

I've run OEM bearings to 8,800 RPMs/28 PSI boost, and they were fine with Castrol GTX. I've run OEM bearings to 8,000/28PSI and they showed a little wear with Rotella T6.

I would run OEM bearings to save cost if needed before I skimped on rings.

Trans fluid isn't needed for engine cost.

180 grit on the hone is wayyyy too rough for mazda rings. Ask me how I know....

 

I plan on buying a second car next spring. I think I am just going to rock the miata until then, with the junkyard. The most popularly debated subject at the moment is what to run on the new motor. I have strong support on both sides for wastegate only, and 12psi on T25. I am honestly leaning for the wastegate only at this point. I am definitely running E85 on the new motor, but if in fact this motor turns out to be bent rods, that doesn't really make me feel any more at ease.

 

I ran 17 PSI on a stock motor for a year. It had bent rods before I started from a nitrous accident. It ran fine, I ended up damaging the keyway on the crank from the vibration though.

If your goal is max power on a stock motor, the recipe is:

Big(ish) turbo
Big exhaust
Lots of fuel
Good charge cooling
Conservative Timing

All of which reduce chance of detonation (breaks ****), and reduce peak pressure (bends rods, breaks ****), and raise average pressure (HP)