I've saved up a little bit of money and want to start putting together the parts for my new motor. I have an 03 w/ a Hydra, WI, BEGI S5, GT3071 w/ 750CC injectors. I'd like to go "all out" for a daily driver street build and want to max out my 3071. Hopefully I can get near 450whp with WI and rev to 8500RPM. My current 250whp really isn't fast enough for me and I don't like losing on the highway (lots of fast cars around here).

I think I have the general idea of what the parts list would be but I really need some feedback. I'm new to cars and still don't understand a lot about engines. I'm not going to be doing the assembly myself since I halfass (v) meticulous work and am sloppy. I'm the type of guy who would do something like that hideous eclipse build that was floating around the net.

Here's the partial list for the build and my thoughts. Let me know what you think. I have done research but there's a lot of discussion on this stuff without consensus sometimes.

9:1 pistons - brand undetermined, .2 or .4 overbore?
Piston clearance - I've read a lot of discussion about this with no conesensus
Piston coatings - not sure if this is worth it
H beam rods - brand undetermined
Rings - brand / type undetermined
ARP studs
Billet Oil Pump Gears
Harmonic Damper
Valve spring kit - I'm not sure which valve kit to get

Anything I'm missing other than seals?

 

I think your missing a little reality. No offense, seriously. The thing is, try driving a miata with half that power goal of yours. Our cars weigh njust about nothing so it doesnt really take all that much to beat "fast" cars.
To put it into perspective, a 220 rwhp miata can easily beat a C5 vette if you drive well.

250 rwhp, and seriously, not much will be able to hang with you on the street.

 

Now your list, the stock motor on a 89-97 is 9:1 and plenty strong enough to with stand 240-50 rwhp. With a good tune, the motor can hold out for about 50hp more however thats when you have to start thing about your tranny as it can easily go kaboom with 240rwhp.

For extra insurance, i would go with forged rods and pistons. That is IF you would still be willing to cross the 300rwhp mark. No need for piston coatings. Yes it helps but its not a need.
No need for the harmonic damper either. Over the 300hp mark, youll want to look into possibly getting a better oil pump.
No need for the valve spring kit either. I have titanium valve springs in my car and its cool but not nessecary. Sooooooooo ill let some one else chime in now.

 

Based on his sig, he's probably already at 230-250.

 

fae, do you have a dyno of your current setup? I'm dying to see the torque curve of a GT3071R at 12psi on a 1.8 Miata.

Sounds like you have the right idea on parts. (I am working off the exact same list LOL)

I chose to go cheap on the hardware:
Supertech forged pistons (came with Nippon Piston Rings)
CAT rods
Boundry Engineering billet oil pump gears (from MT.net group buy)

It will be a while before I am built... have to go turbo first

Sounds like you have more money to spend than I do. I think you should be looking at Weisco Pistons (max overbore) and rings. Follow FMs recommended clearance specs, they will share them over the phone and have posted them at miata.net before. Supertech seems to be the standard bearer in valvetrain components. Coatings only if you are trying to wring out every last ounce from your engine and wallet.

 

Woops-- thought I included current horsepower in first post. It's in there now.

I did get dyno'd. I hit 257 on a Dyno Dynamics and 10psi before any spark tuning. The scale of the graph was wacked out though and I only had a paper readout. FWIW Ed @ York Automotive in Mt. Airy Maryland is very helpful and on the up-and-up with his dyno time. He's a very nice guy and a very experienced racer.

Yes, 250whp isn't fast enough. I'd like to be able to beat 600cc bikes and pace liter bikes. Last night I lost to a GTO with headers and exhaust. He started to walk away around 110. I've also lost to a WRX mods unknown. My car is about as fast as the last generation of M3s. There's also a decent amount of Z06's, new M3s, EVOs blah blah in the area and my little miata deserves more power. It's not fast enough.

I don't know what the torque curve is but my graph looked pretty similar to T3/T4 charts. I hit 12psi at about 4000 depending on the temperature outside. This is with a 9psi WG spring (external Tial). When I had the 15psi spring in there I was hitting 15psi at about 3600RPM. I also have a 3" catless exhaust for teh spoolage and deafness and respiratory illness :(.

BTW I want a higher RPM limit so I can get more out of my boost range and gears...

 

Highway racing =

450whp will be MORE than plenty to roll 600s, not sure about those liter bikes..

 

wow i wasted all that time typing. Anyhoo, ill say it, the miata IMO is not a higway racer. Now my last FD, that was deffinately a higway racer. Sell the miata and get an FD

 

Grrr I do more with it than highway racing. Stuff like driving to work, getting groceries, carting myself to krav maga... No more discouragement please!

 

some 3.63 to 1 or lower gears might be to your likeing, would give you more top end for the highway.

 

Over 300whp Upgradeing the Pistons and Rods are recommended. Valvetrain upgrades are good also, but not nessessary unless bigger cams or valve floating is becoming an issue (i.e. bigger cam and/or higher then recommended RPM). There is no sense in uping the RPM limit as no power will be found there on stock cams. More bad then good can come from doing that. Lastly more boost and a good tune = more power till the turbo is maxed out.
Side note: Try lighter wheel and tire combo = more WHP. I went from 17x7 TSW wheels to 15x8 6UL on NT01 and gained 13 whp on the dyno, plus lost 28 pounds (7lb at each wheel) of dead weight which Changed the whole feeling of the car.

 

^+6325!
At 250whp, 1st gear on a 5spd, even with a 4.1 is pretty much just good for making black dust... at 450whp, you're gonna be hard pressed to get traction through 3rd without some gearing help. You DO want the gear ratio's of the 5-spd to match up with your 6.36, but you're gonna blow a stock 5-spd the first time you slam a 2-3 shift at 450whp. I recommend consideration of the Quaife gearset, which I've heard is between the 5 and 6 speed ratios... but you'll need to practically double your budget.

 

out of curiosity why 750cc inj and only making 250whp?

 

My only suggestion would be to tell anyone who wants to talk you out of the 450 rwhp goal to go back to miata.net.

 

excuse me, I'd like to give you a list of things you don't know...

 

You do know how fast they are right? You need a 10 second car to keep up with the 600s and a 9 second car to keep up with the liter bikes, in stock form. Slammed with a few mods gets them into the 8 second range. Top speed is also a challenge.

It can be done, like anything can be done, but I'll bet it will be expensive if you want it to be reliable. Its not just the motor, but the whole power train, suspension, and tires. At any rate, 450 HP will be pretty nuts

 

Bikes FTW

 

just sell the Miata and buy this eBay Motors: 2005 Carbon Fiber Turbocharged Lotus Elise 275 + HP (item 330283958227 end time Nov-11-08 16:02:18 PST)

 

Cus I planned for the future

 

Well, when you figure out that 750cc's wont get you to 450whp, I'll take the 750's.

Buy the cheap forged pistons/ cheap forged rods, OP gears if you must, studs aren't needed anywhere. I suggest lower comp for a big boost engine, but others will argue. coatings don't do ****.