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Ugh dude that's rough, but glad to hear the cylinder walls still look good. Bummed for the motor in its current state but I will admit I'm excited to watch the new built motor come together and see what times the car can pull with the extra power.
Me too, Zak. I feel bad for Ricardo but this is just speeding up the inevitable, he always wanted some higher compression and cams to go with those trumpets.
I'm more excited about this NA BP screamer than I am K swaps or turbo builds. This thing is gonna be sick!
Been following this thread lately, sucks on the TB failure... I have pretty much the same NA BP screamer project for this winter, just sticking with the BP4w head sinve I have 2 of them and square top manifold. Definetly excited too to see the build motor going into your car!
I appreciate the encouragement, especially Nate dealing with my rambling through DMs. @bigben I hope the thread is helpful in some way. If you have any specific questions I'll be happy to answer what I can.
All head components are purchased and expecting arrival from the motherland. Pistons are the only unknown at the moment because of bore size and the builder told me to wait until they take measurements. I'm also waiting to see what happens with Carrillo rods over black friday. The machine shop (the same Nate used for his engine) has done many a spec miata motor and are waiting for me to yank the motor out. I have had family commitments and clients coming up, but should have time in a week or two, which is also the ETA for the Maruha parts.
I would appreciate any insight into this process being my first time having an engine like this built. So far here is what I've got:
Goal and use: Exciting engine that makes reliable power and a broad power band. Track and Autocross focused, but still dual duty. Capable of 8k RPM, even if not taken there often. Minimal winter driving.
BP6D Head: Maruha 252s with adjustable exhaust gear (per Maruhas recommendation), SUBs, Supertech light double springs, Supertech stainless waisted valves (+0), minimal or no skim. I'll see if the machine shop is willing to do minor port/polish. They'll do valve guides and seals.
Block: Wiseco 10.5:1 83.5/84mm pistons, Carrillo Super A rods (light!). Minimal or no decking.
Supporting Mods: Fluidampr, Billet oil pump, Corncharged, ARP main and head studs, whatever head gasket lets this go together + all other gaskets and bearings.
The machine shop requested I get a torque/honing plate which nearly halted the build because of the CFO approved budget, but was able to find one reasonably priced from a dude in Canada and arrives tomorrow.
I keep going back and forth between the Wiseco's 10.5:1 vs Supertech 11:1s pistons because of 1) piston slap 2) piston-to-valve clearance at full VVT advance, and 3) ability to run 91 octane.
1) I have first hand experience with piston slap in my Jeep and don't enjoy it. I read that the coating Wiseco uses helps to nearly eliminate this noise, but would appreciate people's personal experience.
2) I asked the builder if they would assemble the long block for me, but that would have required nearly a year wait time, so nah. I have a vague idea of what's required to check the piston-to-valve clearance, but have no clue what to do if it indeed has contact. What are the options then? Thicker head gasket? What should the minimum clearance be to account for heat expansion of the forged pistons? Anyone have a write-up I could go through? I also read that Supertech has looser tolerances between their pistons than Wiseco and this could be a problem when taking this measurements. I guess could be easily solved by using puddy on all pistons instead of only one.
3) I want to be able to run 91 octane for cruising in the mountains, and whenever I drive it to events. E85 will certainly be used for the track moving forward, but per Supermiata's build recommendations "Plan your build around the lowest octane you will ever run, not the highest. ", so 10.5:1 and no skimming/decking?
I have one last big question regarding reliability. Supermiata says an engine like this should last 100hrs of track use. What happens after 100hrs? Higher oil consumption? An astronaut rod? The tap dancing of death? Is there any way to tell how the bearings are doing before they spin?
I have opinions on all of this, but I want to keep my mouth closed and see what others think first. Ricardo has already heard my opinions on most of this anyways.
I was already going to give you a cat after reading "corncharged", then I got to the last line Super excited to see this thing come together man. I wouldn't expect anything else out of you, but am super amped to read about the amount of thought you've put into it so far. That being said, I only have some experience that will help with your questions lol.
I can say that I ran Supertech pistons (8.7:1) in my built BP and didn't experience any piston slap when cold. I can't remember the exact P2W clearance I ran but I remember giving the machine shop the Supertech recommendation sheet and telling them it was going to be a boosted motor. That motor did create a decent bit of blowby, though, and the SPS Motorsports guys seemed to know why right off the bat when they checked out my car at GTA.
"Ah, yes lots of blowby, right? Did you build it with Supertech pistons?"
"Yeah, I did. How did you know?"
"They just do that. We used to use Supertechs in our BPs before switching to Wossner."
I can't imagine what specifically would cause Supertech pistons specifically to allow more blowby, and would have guessed that P2W clearance and ring gap would have more to do with it, but the fact that they were able to call out what pistons I was using from that bit of information always stuck with me lol. //threadjack I guess, but I figured that story was somewhat pertinent lol.
Excited to hear from the sages Re: max ideal compression for a flexfuel screamer BP.
Pretty sure I've heard piston slap on the FM Pistons but only through my detcans. I'm pretty sure they are made by Wiseco and have a coating on them. I've never noticed it aside from that. Pretty sure I did the same as Zak and either gave the machine shop the specs from FM or just let them use their judgement.
If you have piston to valve clearance issues then isn't it just an interference engine? Less room for error with VVT tuning I'd assume, but it wouldn't stop the engine from going together, right?
I'll shut up before I put my foot in my mouth, but I'll be interested to see what others say as well. PS, if this stuff is interesting to you, check out Engine Masters. It's mostly old v8's but they do a ton of testing on this kind of stuff. I think it used to be paywalled on motortrend's website but I've found a ton of episodes on youtube recently.
Zak: That's awesome information about the blow-by. If I had to rank it, I rather deal with piston slap than excessive blow-by or oil consumption. The oil consumption nightmare is real after the original BP-4W Scooter had. During my research I came across Leeroy Engineering stating on a Facebook post that they prefer to use Wiseco over Supertech because the piston-to-piston tolerances are tighter, allowing for a less "custom" block, and the possibility of one cylinder having more blow-by than another? I'm certainly interested in more info on this.
SimBa: I had forgotten you were running the Wiseco's from FM. Yes those are the same material and coatings I'm looking to get. Good to know they're quiet! Thank you sir.
Re: Piston to Valve Interference - That's a good point to clarify. This will be an interference engine moving forward, and this is fine as long as the engine stays timed. Broken belt would mean broken valves. With VVT in the mix, even with the engine timed, there is a slight chance the valve can still kiss the piston at full advance with higher comp pistons, and I don't know how much is too much with these piston choices. There is a thread in the forum where someone used JDM pistons w/ maruha cams and had plenty of clearance at full advance. In the Honda world they have a VVT limiter (an aluminum pill you slot in the VVT gear) you need to use with the higher lift cams that prevents VVT advance past a certain degree to cause contact. Learned of that through my friend's K24 swap.
Huh, so maybe there is some science behind the SPS guys' interjection with the Supertech pistons. Not that I doubted them, but good to know haha.
You may/probably have read this already, but you can check for interference at full VVT advance by assembling the motor and timing it with the intake cam three teeth advanced. I think this simulates within 2* of full VVT advance. There's a couple posts about it on here with more details. Obviously this "test" doesn't account for any stretch at high rpm, but if you don't have full VVT advance available, you'll know pretty quickly.
I was not aware of the 3 teeth method to this test. That sounds much more doable to me than the other methods I’ve been reading. I’ll look around for the threads that used that.
first properly fancy part has arrived! Torque plate for a max of 85mm bore.
1) I have first hand experience with piston slap in my Jeep and don't enjoy it. I read that the coating Wiseco uses helps to nearly eliminate this noise, but would appreciate people's personal experience.
My only experience is that forged pistons are loud, especially when temps drop. Just in general, though the noise goes away pretty quickly and doesn't/shouldn't cause any real wear or issues. In the past I had heard that supertechs were quieter due to their metallurgy (low-expansion alloy), or something along those lines, and was under the impression that because of that you would run tighter p2w clearances. Again this is just what I remember from absorbing knowledge over the years, I've never really done the deep dive myself. No comment about the coatings, though in general that is supposed to help with piston slap and wear when cold. With an NA build I'd probably go on the tighter side of spec, where as mega forced induction I'd lean towards the looser side of things. In the end I'd leave that up to the engine builder though, after telling them my use case.
In light of what some others have said about blowby on supertechs that does concern me though, I'd honestly probably just go with whatever Supermiata / @emilio700 recommends. When I don't know the answer I usually blindly follow whatever they suggest and it hasn't done me wrong.
2) I asked the builder if they would assemble the long block for me, but that would have required nearly a year wait time, so nah. I have a vague idea of what's required to check the piston-to-valve clearance, but have no clue what to do if it indeed has contact. What are the options then? Thicker head gasket? What should the minimum clearance be to account for heat expansion of the forged pistons? Anyone have a write-up I could go through? I also read that Supertech has looser tolerances between their pistons than Wiseco and this could be a problem when taking this measurements. I guess could be easily solved by using puddy on all pistons instead of only one.
I'd go with putty, I think it was Greg peters (carpassionchannel on yt) that had some good videos about this on his high compression turbo build. I've always been into lower compression turbo stuff so never had to do this. If your clearances are so tight you are worried about heat expansion causing contact, that's too tight. At least that's the way I see it, not scientific I know. But I think with a undecked head and 10.5 - 11 pistons this won't be a problem. Thicker headgasket can work in a pinch if you need more clearance, but that's not ideal. Something about squish, IIRC.
3) I want to be able to run 91 octane for cruising in the mountains, and whenever I drive it to events. E85 will certainly be used for the track moving forward, but per Supermiata's build recommendations "Plan your build around the lowest octane you will ever run, not the highest. ", so 10.5:1 and no skimming/decking?
This is where my opinion might differ from SM. I still think 11:1 is a good call since the car will spend most of its time above 5,000ft. The extra compression goes a long way up here. It's possible you end up unable to reach MBT at sea level on CA 91 fuel though, but I'm certain you could come up with a safe tune for that circumstance. Add e85/flex like you said for track use and it's a no brainer for me, just understand your street tune might have to leave some on the table at sea level.
I have one last big question regarding reliability. Supermiata says an engine like this should last 100hrs of track use. What happens after 100hrs? Higher oil consumption? An astronaut rod? The tap dancing of death? Is there any way to tell how the bearings are doing before they spin?
AFAIK leakdown numbers start to go up past the acceptable range (over 10%) and oil consumption is up. AFAIK it's not that bearings are going to spin or it will send a rod. And hopefully it would be mostly rebuildable at that point. And don't forget that when they say 100 track hours we're not talking about time attack with warmup cooldown laps in a session, or your average HPDE - we're talking about 100 hours at 100% thrashing and little mechanical empathy, the type of driving that wins races. A little different than what you or I do with our cars.
AFAIK leakdown numbers start to go up past the acceptable range (over 10%) and oil consumption is up. AFAIK it's not that bearings are going to spin or it will send a rod. And hopefully it would be mostly rebuildable at that point. And don't forget that when they say 100 track hours we're not talking about time attack with warmup cooldown laps in a session, or your average HPDE - we're talking about 100 hours at 100% thrashing and little mechanical empathy, the type of driving that wins races. A little different than what you or I do with our cars.
I will only add that what you do in between also counts. Frinstance I changed the oil between every meeting with my 8k rpm screamer engine in the race car and generally gave it a bit of TLC, and when it was stripped for a refresh the builder just put a gasket kit in it and said good to go. That was a couple of years sprinting/TA, with a few races.
I found a good bit of information about the clearance checking on an engine blueprinting book, and they explain the putty method and clearance requirements there. It's always helpful to have more pictures and videos too, so I'll check Greg's video again. Regarding the head gasket, the book agrees with you, and it says that 0.030" to 0.040" is the right squish, so with the minor decking/skimming plus a 0.040" gasket it will be in the sweet spot, and hopefully not need any more clearance with the right pistons. Apparently a lazy squish can also promote knock, so yeah.
The builder agrees with you about the compression. He told me to just get 11:1 pistons and reduce timing at sea level. There is also the possibility of adding coatings to the piston which increases the knock threshold on gas for a couple hundred bucks. I'm still not sold on the Supertechs though, and maybe I should ask in the main forum to get a wider audience. Since this isn't a road tripping car anymore, I don't really plan on driving to sea-level and when I do it'll probably be for a trackday on corn. I should also add a Bosch knock sensor to the misc tab in the spreadsheet...
Gee, that's good to know and thanks. Speaking of which, and sorry if I've asked before, but I would love to see or read about your atmo racecar. I've seen you mention it a few times, and well, I need to learn haha.
Got started on the disassembly yesterday. Drained the oil and although darker than expected, it didn’t have a large amount of glitter. There was a little bit that came out at the end, but doesn’t seem ultra alarming yet? No signs of damage on the intake ports although we know the pistons are hammered. The ITBs are in need of a proper cleaning, so I’m going to contact Borla and have them clean and rebalance them.
Quickjacks are awesome
Small amount of glitter
The plan is to have the engine out tonight. Still have a few more things to unhook and trans to drain. Once the engine is out I’ll cut open the filter and see what that looks like. Then lift the head and enjoy the carnage.
Some updates. Get the engine out yesterday, and the rods arrived today. Planning to look for carnage on Sunday and would like to drop it all off at the machine shop next weekend
I expect that nut is firmly imprinted into the head and the piston is tapping it each revolution. That's my guess, at least. Maybe the washers went straight thru. Ha.
Called it! That's hilarious. Glad the cylinders look good!
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Super excited to see this thing come together man. I wouldn't expect anything else out of you, but am super amped to read about the amount of thought you've put into it so far. That being said, I only have some experience that will help with your questions lol.
