What not to cheap out on?
 

I've been selling off a bunch of misc stuff I've aquired but never used. Have a little pile of cash I'd like to put into the car to move to the next power level. Right now running a stock 94 motor, tranny, torsen rear end with BEGI s4 system, gt2860rs, 2 1/2" enthuza, rx7 550's, mspnp. Suspension and brakes are handled.

I've been running around 12psi for about a year and a half now. With my system that was about 240 rwhp. The existing turbo parts, injectors, exhaust should be good enough for making high 200's low 300's

Have to do some head work currently anyway, leaky seals, so I'm thinking it's a good time to upgrade. What I'm thinking...

Mtuned rods - $300
New rings on existing OEM pistons
Junk yard 99 head - $250
DIY refresh of head - $50 ( valve seals, clean up existing valves, dremel port and polish)
Deck head - as needed - $100?
Rod and main bearings - ACL or Clevite - $100
Ebay timing belt kit $100
Ebay engine gasket kit - $50
Decent junk yard 6 speed - $600

This looks like a bare bones list to me for the jump to 300-320hp. What else would I be a complete idiot for not doing? What can I do cheaper or cut out?

Some possibilities...

Oil pump gears + $190
Forged pistons + $400
OEM gaskets + $200
Block hone + $100
New valves & springs cheap + $180
new valves & springs - supertech + $600
Keep stock tranny and pray - $600


Cars a daily driver + track day car. As a daily driver it needs to be reliable. As a track day car I'm not out to set lap records but I'd love to jump up a notch in what cars I'm outclassing or hanging with. Reliability is a big issue but I do drive with some mechanical empathy at the track. After all I drive to the track and back and gotta make it home at night.

You must hone the block and I recommend a valve job and oil pump gears. A valve job is a royal bitch and requires too much precision work for me, and the oil pump gears can only be done when the motor is out and failure is cataclysmic.

Absolutely hone the block.
I wouldn't recommend billet opg's but thats my opinion.
My fleabay gasket set is on the car and is holding up.
rings will cost a shitload from dealer. I suggest rockauto.
Absolutely get rods

You must hone. I wouldn't want to attempt that power level on cast pistons. Forged for that little extra forgiveness that might save you a shitload of money and trouble. As for the OP gears and valvetrain, I'm not worried unless you plan on exceeding the stock RPM range.

Take whatever head you use to that shop I suggested. They are an incredibly reputable SM shop, loads of experience in there. They'll tell you what you need to do in terms of seals, valve jobs, etc. They'll also tell you what they can do and for how much in terms of power adders. Do what they tell you do to, and then if you have any money left over in your budget, do a few of the things they suggest, they know more about what they're doing than a lot of us on here.

One more thing, I have NEVER paid a cent more than the original quote unless I call them up and tell them to spend more of my money. Great guys, can't stress that enough.

I knew I'd have to hone if I went aftermarket pistons. Thought I might get away cheap if I could put new rockauto rings on my stock pistons and leave the block alone.

I guess I'll have to head to go to Curly's shop for advice/ consult to determine costs. I'll also talk to them about the hone on the cylinders. That'll give me a better idea of where I need to be machining cost wise.

OPG's seem to be up to debate. They blow your motors gone. Easy to replace while an engines out, not easy later. Couple hundred bucks to save not doing them. grrr....

God I wish I was richer. This would be easy if I had 10k to throw at it.

you still need to hone even if you just replace rings and keep stock pistons.
You can buy a honing tool, read up on it online, and "clean up" your cylinder walls for a very low price. You only need machining if you want to go with bigger pistons (aftermarket).


As for the opg's, tell me something: how many threads have you seen in the past year with people breaking them? That's the question a very knowledgeable person asked me. There are what, 1 person? 2? I haven't seen even a single one.

While we had people melt cylinders, bend/break rods, blow gaskets, and all kinds of other shit.

Just my opinion.

There are a lot of little things and might-as-wells associated with a build that you've not accounted for. Realistically expect to come in the $3000 range for a middle of the road "best value" build. This includes forged OS pistons (no replacement for displacement) which will come with rings.

I'd also look at the engine management. Upgrading to the MS2 will only cost you $100. And get in on the crank wheel group buy that emilio is teasing, if it comes to fruition.

mine was $2000 including rods and pistons and instructions to "make it a fresh, zero-mile engine and call me when you're done."

For the head too?

BEGi S4 with a 2860 and only 2.5in exhaust? How about a 3" setup to open things up a bit...

I agree with 18psi on the billet oil pump gears. Nice product and potential piece of mind, but with rare recorded evidence of the OEM set failing, you can save that money for other parts of the build.

Also, after reading a lot of threads on here about the subject, the stock pistons should be fine for reuse for your targeted HP. It's a lack of solid tuning that has broken OEM pistons or ringlands, not the power output. I had mine tri-coated, machine shop got some good rings, and called it a day. The other problem I had with forged pistons on a daily driver was the loose clearances required in the cylinders until the pistons warm up and expand (on a track car or weekend driver, the choice would be forged). Yes there are forged pistons on the market now for our cars that don't expand a lot, but they still will wear the cylinders faster than an OEM set and it was money I saved for other aspects of the build.

yes, including a "valve job" and cleaned-up castings in the runners. I showed up with pistons and rods, I dropped $1300 and he did the work and provided everything else including the balance.

I don't get any piston noise and went with a "loose" bore. why do forged pistons wear cylinders faster than cast, considering they don't touch the cylinder walls?

They wobble a little more then OEM pistons at OEM clearance. Wobbling in any case is bad. Its not something I'd cry over but its there. I can definitely see it causing a little more wear. It's not like your walls are going to be scraped to shit in 10k miles.
What's "loose"? As in whats your clearance?

Dunno but the guy who did the work does tons and tons and tons of FI miata motors that all see track time and he has a phenomenal reputation for reliability.

Forged pistons can touch the cylinder wall when they're cold, that's what piston slap is. That's becoming a thing of the past considering piston makers are using better materials, but the loose clearances are still there because they have to be, which allows for more wear and tear.

I wasn't suggesting that it causes unreliability or that your engine will wear out after 25k miles, but personally when I daily a car I put a lot of miles on it and there's a lot of warm up time in there after starting and stopping quite a bit, thus increasing the chances of accelerated wear. Of course, everyone's version of what daily driving is will be different. But I liked the longevity idea vs. the overall power ability, especially when cast pistons are plenty strong, that's all.

I'm agreeing with Rotornut. I'm thinking stock pistons aren't failing commonly unless pushed REALLY hard, poor tune, bad injector, oil starvation, etc, all things that eat forged pistons too with a 300hp goal. Oil pump gears again are a maybe and not a common loss at 300hp.

Stupidly I'm thinking I'll buy a $30 hone tool and rering the stock pistons, clean up and reuse the stock valves and keep this as low budget as possible. If there was only a cheap way to put in a $100 TII tranny vs. the 6 speed, that would cut out a big expense.

When I blow up 3 hours from home you can all laugh at me!

No one will laugh at you. That sounds like a great idea to me, just have to execute it correctly.

if you're keeping the stock pistons, why not ceramic coat them?