Michał

Hi everyone, i have 2003 vvt miata, so if i want make some nice power on this engine and shred this bitch, i have to rebuild engine and the problem is thinking about correct parts and setup making me more crazy everyday,
My dream is make 350 at wheels but i think is impossible because i will be always limited by 6 speed strengh, i really like launches and smoke some tires from time to time, do a little bit drifting or some kind of races ocassionaly,
So if im limited by gearbox im more into 300 at the wheels and that makes me think maybe i dont need to change some parts, i also want to build most possible strong and efficient engine to easy max out turbo


Already have:
-really low mileage engine on stand
-Garrett gt2560r which can give me 300 whp but i can replace it with gtx2860 gen 1 for cheap an have enough headroom for 350whp
-honda skunk2 with 70mm throttle body fitted to mazda flange
-no power steering pump
-water pump replaced with electric one so it dont take power from crank
-rest cooling system is replaced with overkill stuff so i have no worry about cooling
-bosch 630cc, i think i don't need biger cause i dont have option to run e85
-audi cops
-lightweight flywheel
-china rods
-snow performance water meth injection to have more safety with pump gas


I wanna order
kraken low mount manifold and dp to have max flow, im crying about that cause top mount looks much better but performance at first
-supertech forged 9:1 85,5mm pistons cause it give me 2l displacement, is nice to have 2l but i heard about it makes cylinder wall to thin, is it true?
- full arp bolt kit, i don't have question about it
-cometic hg, also no question
-boundary oil pump with ati super damper - they are necessary for my goals? maybe one more than the other
most questionable thing is valvetrain
- i think about order +1mm set of supertech valves to improve flow and durability, probably i killed my exhaust valves in old engine because of to much play with two step but is it worth to put into 300 whp car?
- supertech heavy double springs, do they have enough preload? i saw that sps motorsport recommend 85-90lbs, supertechs have 74lbs, can i safe spin vvt engine little bit more? like to 8000?
-what valve seals do you recommend? i saw many bad opinions about supertech ones
-do i need upgraded valve keepers and valve guides for supertech valves? or stock also fit and will be good
-acl race bearings but also saw few bad opinions so baybe king racing?

Do i have to think about something else?
Is fab9 a good place to make order? i want buy everything from one place cause im from europe, and i saw few opinion that they taking order and dont sending stuff for long cause they dont have something which is on their site as aviable
Thanks for advice

rwyatt365

First, your 6sp should be able to handle 350 if you have some "mechanical sympathy". Bu since you want to smoke the tires and drift, I don't suspect that a 6sp will last.

Regarding your parts list...you should seriously think about upgrading your injectors - at least 750cc for 300 whp, or just go up to ID1050's for all the headroom you'll probably ever need. If it was me, I'd not go more than an 84mm bore, especially if you're going to flog the engine - but that's just me. You probably won't notice the difference between 1.8 & ~2.0L. Beware of a sticky oil relief valve on the Boundary oil pump. Check it before installing and make any necessary adjustments. DON'T use ST valve stem seals! Some are good, but most will leak. Buy stock seals if possible (although I've had good luck with FelPro seals - so far). My experience tells me that "regular" (not race) King bearings work just fine. I've spun ACL and King race bearings - that might have been "pilot error", but the last set of regular King bearings has lasted. I replaced the original crank damper with a Fluidamper in my last build. I haven't noticed a difference from my "seat dyno", but it was a worthwhile investment IMO. I choose that over the ATI because I didn't want to hassle with the interference-fit of the ATI. Over 23 years of ownership, 330K+ miles and 3 rebuilds I haven't changes valve guides or valve keepers. Maybe I should have, but I haven't.

Personally, I won't order from Fab9. I've had bad luck in the past with slow shipping, wrong parts and lack of communication. It's just not worth the hassle for me. I don't know if they've gotten any better over the past 5 years, or so, but "I Won't Be Fooled Again" (The Who).

Michał

Thank you for reply, due to my localisation im more into bosch ev14 injectors and adapters, i can choose between 630, 750 and 980cc, friend made 300whp with 540cc but injectors was maxed with this power, i Will think about bigger ones, i thought about big pistons cause it will make engine more torque even with lower compression but i must do more research about that or measure cylinder wall thickness, about gearbox i have few ideas how easy lowered power depend on situations, so i think make 350 whp build and "less power button" for hard driving, if there Will be no other choice i Will Save money for bmw transmission swap, still dont know what to do with valvetrain if +1mm valves doesn't give much gains i think it will be better to change for standard size, but i dont saw any compression or dyno data

rwyatt365

I was able to get to 250+ (maybe even 300, no dyno info in later iterations) HP using 620cc EV14 injectors from Injector Dynamics. The only problem is that they were at more than 80% duty cycle at full throttle (sometimes peaking close to 90%). In other words, you won't have any room to grow with anything less than 600 or 700 cc/min to achieve your desired power levels.

I have my own opinion about the valves (that is not backed up by any hard proof) and that is; I don't think that modifying the BP head will net a whole lot of gains. There's empirical evidence that you can gain 10's of HP with bigger valves, porting, "aggressive" cams and cam timing. But you can unlock the same (and more) with a twist of the boost control. If someone was going full naturally-aspirated, then go for it. But on a boosted car, I don't think that the power gains are worth the time, energy and effort. Just my two cents - take it for what it's worth.

If I could get my hands on a BMW trans, a Getrag differential and about $10K, then I would swap out the Miata parts. But...I will make-do with what I've got.

Michał

I also thought that +1 valves Will not give much gains, maybe i change them to other stock size valves to improve durability, i won some exhaust competitions last year and was fun to beat 100k $ cars, but i think it damaged my exhaust valves so maybe change only exhaust to inconel ones, for me bmw trans swap cost 4500$ which is not much less than whole engine build, but maybe some Day