I tried posting this on two other forums, but I guess no one over there knows much about building engines So levnubhin suggested I post it here, any help would be very much appreciated.
This is the second engine I've had in my NA, the first one died of a spun rod bearing so I bought the current '96 1.8 engine with an alleged 26,000 miles. Then after driving it for 25,000 miles, it too gave up on life. I'm beginning to think it has about 100,000 more miles than I was told it did.
So now I am trying to decide if I want to take that risk again and buy a low milage '99-'00 engine or get my '96 rebuilt with stronger components.
I have absolutely no idea where to start as far as getting my engine rebuilt. I know FM will build you an engine if you are willing to sacrifice your 2/3 of your limbs. And I found this site, Racing Mazda b series engine , which is reasonable, but apparently they don't exist anymore.
I don't plan on turbo'ing my car, but IRTB's are definitely in my future. If I rebuild the engine I will definitely want a 99-00 head, but what else should I consider? I do about 8-10 track days a year and I might start doing some NASA time trials. What should I have done to the bottom end? 11:1 pistons? Which ones? Should I bother with rods since it won't be boosted?
Thanks for any help, after 6 years I've been able to pretty much bolt everything on or off, but this is a bit over my head.
If you are staying NA, yes on pistons, no on rods. Might as well bump displacement by overboring 1.0 mm while you are at it. Plus, it gives the shop a chance to go through your next "supposedly low mile" engine.
If you're not looking to break horsepower records, or at least get honorable mention, why are you planning on spending so much money? Grab a hanes manual, a rebuild kit, give the entire rotating assembly, block, and head to a machine shop, and when you get it all back, start learning. If you go the camshaft, ITB, high compression route, your return will be no where near your investment. The SM guys are getting 120hp out of a 1.6, which is plenty "strong and peppy" and you'll be able to start with a 1.8, and break a lotta rules.
This is all just my opinion. After rebuilding my own 1.6, it's survived numerous track days while NA, and now it's a dedicated turbo'd track day car. I don't blame you for staying NA, but if you're going to do that, supposedly to keep things simple (that's generally the biggest reason anyways), do just that, keep it simple.
Edit: Dear lord that sounds horrible
Last edited by curly; 07-29-2009 at 08:26 PM.
Reason: watched video
Jimmy at fujiracing runs he's ITB setup with a 99-00 head ported, adjustable cam gears, not sure on what valve/spring combo he's running but it revs to 8500-9000 rpm on the track. Meanest sounding n/a miata I've ever heard lol. He runs some 11:1 CR pistons and not sure on the rods. I suppose one advantage to some forged rods is that they'll be lighter. He's running a AEM ecu with that engine setup and boasts a impressive 185rwhp and 135ish ft-lbs of torque (didn't see a dyno sheet but I didn't doubt it after seeing it run).
I agree with what the others said, new pistons,bearings,head studs, and machine work. Have your block and head checked out by a trusted builder and ask him what else might need to be replaced. Maybe your shim clearances are fucked, maybe you flat spotted a cam lobe, maybe your crank is unservicable. Just need to have someone that deals with it on a daily basis take a look at it. Trust me, I'll be coming up on my 4th engine in this car and this will be my 2nd "built" motor lol.
You could reassemble it yourself but I didn't because I don't trust my abilities 100% and would be paranoid all the time lol. But thats just me. Good luck with it, this group is very helpful btw .
Oh and that sounds nasty, nastier than my spun rod bearing or clogged oil ports with piston slap and major valve train chatter or hammered down rod bearing lol. Sounds like more than one problem but you never know until you pull the engine and tear it apart.
I couldn't find much info on Endyn working on miatas.
Wow, I knew about the OGK, but after taking a look at Emilio's blog it looks like he and I are going to pretty similar engines. And he was able to get 158 whp without a 99 head
UrbanSoot, I'll let you go ahead with your build and just be envious of your ballin' engine. Instead of getting a set of aggressive cams, for now I may just go with the MSM intake cam, keep the 7200 rev limit and if later on I want more I'll do valve springs, and some serious cams.
I think I should mention that the reason I'm not looking to make big hp numbers is because I actually liked my miata being a little slow at the track because it gave me greater satisfaction at the end of the day when I looked back on all the faster cars I was able to get past and keep up with. And it was even more of an ego boost when those drives came up to me afterwards to see "what I got under there" and watch the the surprised looks on their faces when they see its just NA. With a turbo, SC, V8 etc, its easy for them to say, "Oh well, its got power adder thats why you got by me." So since I'm rebuilding the engine anyway, I figure why not spend about a grand more than I would with a standard rebuild and give me a little more of an NA advantage. Oh, and if I do have the need for speed I have the option of driving my father's Cayman S, or my MD's GT3.
I think I may start feeling the same way when start doing the NASA time trials.
The grass is always greener. When I basically had the fastest street car on the track (aside from the TDR car that I only scored a few laps with), I wished I had a few little scuffles on the track. When a prius pulled me on a straight I wished I had power.
I've pretty much gathered that 8k is out of the question without more head work, which would put be well over my budget ($350 springs and $280 valves). However I was talking to Emilio from 949 and he said I should put the valve springs from the 96 head when the 99 head is rebuilt. Are the 96 valve springs that much better?
Also I rode in Jimmy from Fuji Racings' Miata today and it was very very impressive, reving to 9k, idling at 1k easily with aggressive cams, but after seeing IRTB's in person I think I'm going to hold off until my NA is no longer my DD. There are too many variables and fine tuning that has to be done for me to feel comfortable relying on my car to drive me 50 miles everyday and also tracking it 10 times a year.
Some things that I'll be including in the build is a Fidanza 8lb flywheel, Samco hoses (heres why at 1:26), competition motor mounts, MTuned coolant reroute, and COPs
Some things that I'll be including in the build is a Fidanza 8lb flywheel, ...
Instead of changing the flywheel, knife-edge the crank. You'll get the same general effect in regard to reduced rotating mass, but will gain a benefit through loss of drag within the oil bath and reduced frothing.