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Maybe also replace the 12 point screws with black buttonheads.
I think that looks close enough to stock, replacing or painting the screws would help disguise it.
Well, I found a 94 block.
I will get a better look at it and post some more photos once I get it out of the trunk and onto my new engine stand. It came from a car with a 200k mile car, but it was only $30. Crankshaft, oil pan and main caps included.
If it doesn't work out I'll consider it a cheap lesson.
Harbor Freight 1000lb engine stand to the rescue. I bought M12x1.5 bolts from the hardware store and bolted the stand mounting plate to the engine while it was still in the trunk. Then I carried it over and slid the mounting plate into the stand. It was heavy but manageable alone.
The precious oil feed port:
There's a machine shop close to me that turned my flywheel when I changed my clutch. I'm going to call today and see if he'll take a look at this block and tell me if its garbage or not. I'm not sure how much I should disassemble it before I bring it in. Probably best to just ask?
I have a lead on a 99 cylinder head, might be able to get it next week. I've been reading threads here about issues with Supertech intake valves and I'm concerned enough to decide against them for now. It seems like there were fewer problems with the Manley stainless intake valves, so I'll go with those and the Supertech +1mm inconel exhaust valves. I haven't come across many reports of those failing. Alternatively, depending on its condition, I could just leave the head mostly as is, have a valve job done and slap it on.
I thought the volvo springs were no longer in vogue since TNTuba showed data saying they started fatiguing rapidly and lost a lot of seat pressure once you went past like 7000rpm with them? Like, dropped enough seat pressure to where you'd have been better off keeping stock springs..?
Gonna have to go find TNTuba's thread. First id heard of that. Pending a good read, however, you can buy the Volvo springs manufactured by VPAutoparts. Just make sure you get 2 sets.
Gonna have to go find TNTuba's thread. First id heard of that. Pending a good read, however, you can buy the Volvo springs manufactured by VPAutoparts. Just make sure you get 2 sets.
Specifically post 97, which is from TNTUBA. Doesn't give specific numbers, he might elsewhere though, but references a ~15% drop after just half an autoX season. Yes, his autoX season is a lot different than most of ours, but still relevant info. I think my comment about stock springs being better was borne from info higher in the thread, where someone references NA8 springs being the best of several tested when compared to price, which my brain conflated with the seat pressure drop TNTUBA saw.
Very interesting. I'm not too worried though as my project is a streetcar that won't live on rev limiter. I imagine his springs experience a significantly larger amount of heat/stress than any streetcar.
Specifically post 97, which is from TNTUBA. Doesn't give specific numbers, he might elsewhere though, but references a ~15% drop after just half an autoX season. Yes, his autoX season is a lot different than most of ours, but still relevant info. I think my comment about stock springs being better was borne from info higher in the thread, where someone references NA8 springs being the best of several tested when compared to price, which my brain conflated with the seat pressure drop TNTUBA saw.
Originally Posted by Jumpster74
Very interesting. I'm not too worried though as my project is a streetcar that won't live on rev limiter. I imagine his springs experience a significantly larger amount of heat/stress than any streetcar.
#threaddrift
That was a great read, thank you. Now I'm even more undecided because there are reports of the SuperTech springs losing seat pressure as well. That the Volvo springs could be worse than stock is worrying.
As another option, Treasure Coast sells rebuilt cylinder heads. Price for 99-00 heads seems high at $950 before shipping, but I haven't gotten an estimate for cylinder head work from a machine shop before. I'm wondering if in the end it's about the same amount that I'd pay to buy a high-mileage head and have it rebuilt locally.
I've got a bp4w head that I would sell pretty cheap if you're ever up in the bay area (not interested in shipping).
You'd want to have it hot tanked and have the cam bores inspected as it came off a motor that spun a rod bearing, thus the pretty cheap part.
Thanks! I'll certainly you know if I'm heading up that way. I'm getting the impression 99-00 heads are difficult to come by.
I had a good conversation with my local machinist. He does't have a torque plate for a Miata engine and recommended finding a shop that does a lot of Miata engines and has one. I imagine there has to be a few in the LA area. He strongly recommended Carillo A-beam rods over the Manleys, so I'll take that into consideration. We also talked about bore options. I'm pretty set on the supertech pistons since so many people on here run them successfully. So I have to decide between:
83.5mm; 8.6:1
83.5mm; 9.5:1
84.0mm; 9.0:1
8.6:1 is the go-to compression ratio for turbo builds here, but I'm worried that I will run into issues when I have to use the stock ECU if I'm dropping almost a full point of compression. I've seen a couple posts where people suggested it would be fine, but haven't come across anyone that explicitly stated they ran 8.6:1 with a stock ECU (preferably 99-00) and didn't have any check engine lights or codes. If I put together my motor, run a bunch of timing and live the dream for 2 years, but then go back to stock and have a CEL I can't get rid of without pulling the engine it's game over.
9.5:1 would just be the same nominal compression I have now. Safest bet, but leaving a lot on the table.
9.0:1 seemed like the happy medium, but I have to go up to 84mm instead of 83.5. The machinist emphasized boring the least allowable to preserve the cylinder walls. I've read at least one build thread where the poster was able to run a stock 99 ECU with 9.0:1 without issues, so that's a huge deal for peace of mind. And I believe I might get slightly better spool at the expense of being more detonation limited at the top end vs 8.6:1. Running a 2554R, I already made the choice to prioritize response over peak power. But is it worth the thinner cylinder walls? Again, I'm only going to make 220 or so whp with this thing. I certainly want the engine to be robust, but it's not going to be making huge power.
Leaning towards 9.0:1 still, but very interested in hearing opinions, especially if anyone has personally run an NB on the stock ECU with 8.6:1 compression.
Torque plates are always a good idea but sometimes they are more necessary then others. The way I decide the importance is by the block material, how close the head bolt holes are to the bore and the diameter of the fastener. In the case of the miata I not sure how much of a benefit it really is.
I just bored and honed my block. After I run it I will do a leak down and post the results in my dyno follow up. As far as rods I have used the manley’s and the carillo super pro a rods in this build. Carrillo’s quality is very good, but conceptually they missed it on the rod design for this application. The cost of the A rods makes them a lower value then the their H beam since the H beam comes with Carr bolts. If I build one of these again it will be back to manley.
I have been using the ST med doubles and I’m not a fan. All springs degrade and in a hp application they are a consumable component. I do not like the heavy steel spacer they use in their design. Reminds me of a slide hammer. I would prefer a heavy single with ti retainer paired with a lighter valve. Maybe a na8 spring with a ti retainer and subs would have a acceptable ceiling. Also the oe springs can be shimmed a little to increase the seat pressure.
The st/mahle pistons are the best option because of the 4032 alloy and the offset wrist pin. 83.5 or 84 is no problem and neither is 8.6:1. The head and block will both have the deck surfaces machined so the final compression might be closer to 9:1. The 9:1 is also a good choice. I went with the 9:5. Make sure you run at least .0035” piston to wall clearance and deburr (massage) the piston crowns.
Updates. Thanks again to you all for the feedback. I've made a few decisions and bought a few more parts. Here's what I've got so far, as well as the damage:
I haven't paid retail for anything, barely have that many parts and I'm already into it for > 1k. It is what it is, but tracking the costs has been a good motivator to really narrow my focus on what's necessary for my power level rather than just trying to get the best everything.
I was lucky enough to find a refreshed 99 head for sale that had a valve job performed and was resurfaced. Even after shipping I think it was a decent deal at $500, including a valve cover, fuel rail, and a few odds and ends I was missing on the block, like the power steering and ac brackets. Within a couple days I saw 2 high mileage BP4W heads pop up for sale for locally $200 and $300, but I think after considering machine shop costs for getting either of those ones refreshed, I came out ahead with the one I bought. I'm going to use the head as is. After doing more reading, I don't think it's worth going down that rabbit hole for my modest power goals.
I had originally planned for Manley rods, but by many accounts on here the Eagle rods are very similar or potentially even the same product so when a set came up for sale I bought them. Unboxing and pre-inspection:
ARP mains and head studs. The head studs are not the stronger HB variety, but should be more than adequate for what I'm planning to do.
I'm going to go with 84 mm 9.0 Supertechs. Haven't pulled the trigger yet, but I expect to have to pay retail for those. I'm going to wait a little bit just in case I get lucky, but then the pistons and the billet oil pump will be the next purchases. Had the chance to buy an ATI damper unused at $350 but passed. I'll be reusing my OEM damper that has only a few thousand miles on it to avoid the extra headaches of installing/removing the ATI and keep costs down a bit. If my use case for the car changes in the future, I think I'll buy a fluiddampr.
Decided to go with OEM bearings instead of ACL race after reading a bit more about wear. I'm thinking that I'll go with as many OEM parts as possible in this build except for instances where there's a clear pattern of failures for boosted applications(rods, oil pump). I really want to get good longevity out of this engine.
I found a machine shop with a Miata 1.8l torque plate. Since I have the option available, I'll take it just in case there is any benefit. I'm going to take a trip over within the next few days and see if they'll work on my block.
Decided to go with OEM bearings instead of ACL race after reading a bit more about wear. I'm thinking that I'll go with as many OEM parts as possible in this build except for instances where there's a clear pattern of failures for boosted applications(rods, oil pump). I really want to get good longevity out of this engine.
I hadn't heard that about ACL race bearings before, can you elaborate?
08-27-2020, 12:27 AM
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