Low boost built motor?
 

Instead of boosting the shit out of my stock motor...could it be beneficial to build a 1.8 with turbo pistons and lightweight rods, have everything balanced, get some headwork done...basically make my engine more efficient (better flow, less restriction), but for a low boost application (6-8psi)? What engine upgrades are there or what can I do internally to my engine to make or free up more horsepower? I feel a stock miata engine is underpowered, what makes this engine that way? What restrictions are there that can be removed?

with a low boost motor, I'd raise the compression and do major headwork.

Low displacement, non-honda heads, too much gay.

If you remove the gay you should realize a 33.3% power increase.

Low boost sounds cool. But if you are spending the money to build your motor. And spending the BANK on a turbo.
Why not have crazy power? Either way; High compression low boost or low compression high boost. It still takes away from the dependability. That is compared to stock.

Now if you have parts available cheap, or setting in the floor doing nothing. And you need a plan to make it work, that is different story. Just my .02 cents

What kind of headwork can be done on the 99 motor for more power?

everything....

I don't know anything about that kind of work. Care to elaborate or shall I google? =P

Like valve job and port + polish?

cams, valves, springs, porting, deshrouding, gears, blending, etc etc etc.

Start with what you have money for, and then define your specific goals based on that budget.

Hehe...

Alot is the answer. If you're unfamiliar search the forum for some threads on this subject.

On my 99 head I did some MAJOR unshrouding (not your typical unshrouding job), undercut valves, blended the bowls into the chambers and throat, reduced the short side radius, pollished the combustion chambers, removed any casting marks from the intake ports, and pollished the exhaust ports. When finished the car got so much more air that it was slower when I floored it because the stock ECU wasn't adding near enough fuel. Car would buck, backfire, and fall on its face. After Megasquirt it was ALOT quicker than stock.

Will do. Sounds like doing that kind of work can make a big difference. I'm sure it is not very cheap either. Sounds like a combination of engine work along with a turbo could make some nice power.

If you are at low boost why would you bother doing anything to the motor, it just doesn't make sense. Spend the money on some proper managing and turn up the boost, once you want even more power, then build the motor and you have a beast, so start saving for a 6 speed etc. You get the point.

I built a motor to make 250whp with a ton of headroom because I want to put 100k miles on it, drive 4-hours to the racetrack, drive it for 2 hours on the track and crush gt3rs's, then know I'm going to make it home.

I probably would have been ok on a stock motor and a gt2560, but I had the money and wanted to do it once and be done with it.

i built a motor to make 250rwhp without any headroom. i boosted my stock 1.6L.

1. How many miles do you get out of motors boosted like that?
2. Do you have alot of oil seal problems?
3. Why can't the pony speak?......................Cause he is a little horse!....

So back to my question...What can be done to the stock motor to make power, besides high comp pistons. I want details. A stock 1.8 has what, 140hp at the flywheel? I want like 175, on a low compression motor, stock computer...is this possible?

there are plenty +200rwhp 1.6Ls. it's not difficult.

I boosted my last motor for 2 years, almost to the day...maybe 10k. It had horrible oil consumption from day one. unknown mileage JDM import. It bit the dust when i started boosted +15psi and running aggressive spark on a +90° day.

this new motor was $200 score. engine overheated, sat around for years at a shop. simply slapped a head on the block and went boosting again. I have 0 oil consumption and make around 250rwhp at 12-13psi.

stock computer, low compression pistons? why?!

the pistons alone will kill your power output, especially on the stock ecu.....you're silly.

I have a built engine, and I was thinking about a low boost setup, ben and I were discussing it the other day.

My engine:

ETD Rods
10:1 compression
99 head w/big valves
MSPNP..etc...
a bunch of other small tweaks...

We were thinking a large-ish turbo... perhaps a GT28RS at 4-6 PSI, hell possibly non intercooled. Off boost response should be great with the higher compression and better head, and would probably make <200 hp. For all-out efficency I could run the S4 tubular manifold and maybee the BEGI intake, but that would be taking it too far I think.

throw on a WI system and then you can crank up the boost for the track.

Lowering compression and keeping a stock computer wont make it easy to get much more power. I dont know if that could be done.

See I am planning on doin a build soon, because my the car used 1 quart between oil changes when I bought it last year in March, and it had 103,000 miles on it. Now it's boosted, and it takes 2 quarts between oil changes, and it has 123,000 miles on it. I wanna keep it low boost, cause I like the way it's set up now...it is dependable, very dependable....and I drive it to work everyday and I get around 26 MPG while beating on it. I think it is fast enough for my liking, but I figure, if I do a rebuild, what are my options to keep it pretty much stock, but strong enough to handle boost, but at the same time tame enough for everyday use? It doesn't smoke or leak oil, so where is the oil getting used? Think it's time for new rings? I wanna keep stock injectors and stock computer, so lets keep this thread mechanical please.

This is what I read:

FAIL FAIL FAIL FAIL :blah:


rods are for strength. low boost shouldn't need rods. your rings are leaking so you'll want to in the least rering. (unless your boosting into crankcase). You're make more power on low boost with HIGHER compression pistons. in the least, that will net you the most gains.

On v8's we would mill the heads for more compression. It is a big bang for the buck. The only time you wanna lower compression on a race motor is "boost"

LAYMEN TERMS:

Non-boost: Low compression = vagina
Boost: Low compression = ability to boost more.

Non boost: High compression = Trojan Stallion
Boost: High compression = Lower boost capibilities

It is pretty much that simple. Something has to make more bang. If the bang is less. Less power.

See I am all about efficiency...balance, weight distribution, etc. You could have a perfectly balanced engine with very low rotating mass, boosting, lets say, 12 psi...and have a heavy rotating, shitty balanced engine boosting, say 15psi, and I feel the 12psi would make more power, be better on fuel, and last a hell of a lot longer. Correct me if I'm wrong, but it's not all about simply turning up your boost.

I can see wanting dependable. 1 quart on a oil change is nothing. Are you driving the piss out of it?
I would drive it till it started smoking bad, not in-between shifts, I mean bad. I would just keep check on the oil everyday.
It is an excuse to look at your turbo anyway.

no it's not, and it's exactly why my 1.6L looks better on a dyno than most 94-05s.

but, if you want the motor to make more power on lower boost, raise the compression. since you'll run less boost, your knock threshold should be fine, you'll make more bang for the buck. coupled with increasing the flow it will be a monster.

Plenty of 200+ RELIABLE 1.6's. That's not pushing it very hard.


"Around", meaning "half of" :-P



Seriously, 200 hp out of a stock stock stock NB motor is nothing. Just throw it together, don't worry. If you're going to take it apart, put in better rods.

On my own 2000, I put in rods/pistons from a 97, for 9.0 compression. It's been dandy at 10-12 psi for a while. It's good to be cautious, but that's more than you need, you're killing your gas mileage, etc.

Your magical 12psi motor isn't going to do what you want on the stock ecu. You're right it's not all about simply turning up the boost. It's about building a good sealing motor with a strong bottom end, and tuning.



It's hard to find a heavy rotating, shitty balanced miata motor, unless you make it that way.

You're a perfectionist. So am I. You could easily make 250whp on a stock motor with a good tune and maintain reliability. This is old news. Turbo, Megasquirt, tuning, and 12 PSI you're their. Or you can be a perfectionist and try to optimize everything to make that same power at less boost. Option 1 is more bang for the buck. Option 2 is prefered if you're an engineering type that enjoys tuning, tweaking, and spending time and money as much as driving and passing people.

I read you wanna keep your stock ECU. I'm sorry.

built low compression block + major headwork + stock ecu = nonsense

Thirdgen, I'll ad in another tidbit for you...
You are a victim of believing in Voodoo.

Here's what you do.
Plan on having your car "down" for a month.
Pull your motor.
Take the motor to a reputable machine shop in the local area.

For the head, tell them you want "the works" but rebuilt with a new stock valvetrain. About $1500

For the bottom end, tell them you want a standard rebuild kit but supply them with a set of CAT forged rods you buy from Ben, and you want a tri-coat on the pistons. You also will need a new water and oil pump, and a new timing belt. They will hone the block and balance the crank, reassemble the motor and you'll be out around $2k total.

Take that motor back to your car and re-install it.
Sell SR20det T25 and purchase GT2560.
Then remove the Voodoo Box and get either the Xede or Hydra and some 550's. Or you can wait patiently until Begi has their new ECU ready for the '99-'01 cars.

This is gonna run you in the neighborhood of $5-$6k, but 11-12psi on a good tune for about 250whp and it should last 100k miles. Turn boost down to 7-8psi and run 200whp for as long as YOU live.

I consider myself part of this crowd. If I were thirdgen, and I had to do a rebuild anyway, here's where I would spend my money on a 100% reliable build (in order of importance, excluding turbo parts):

1) Standalone ECU, and lots of dyno time.

2) Oil cooler

3) Coolant reroute

Rebuild the bottom end with stock parts, keep the stock pistons if you want to daily the car, trust me it's not fun HAVING to warm up the car completely before driving it, and you must let it warm up fully on forged aluminum pistons if you want the rings to last.

Do a port and polish on the head, valve job, you can do more to it but with low boost you won't see much gains. Put it together and have a cheap reliable motor and just drive it.

If you insist on keeping the boost low, or alternatively, maximizing the power with a given boost, you should consider spending a lot of time on the dyno playing with cam timing, along with the usual fuel/spark tuning. This is what I intend to do when I can afford it.

building a motor for low anything is crap crap crap!!

my 01 made something like 190 rwhp at 4 psi. bone stock motor. it probably would run hundreds of thousands of miles like that--with half ass tuning.

I ran 40+ hours of track time last year.

let's play a game: which one is the stock 01 at 9psi and which is the stock '93 at 12psi????

Touche.

Tell me which turbo was on each motor, and I'll tell you.

2876 with a .63 T2 A/R on the 01.
T3 Super 60 with a .48 T3 A/R on the 1.6.

IMO there is a difference between being a perfectionist and wasting money.

I talked to Corkey Bell and he said 12 psi is very dependable on a stock 1.6.

I'm not trying to be an ass. Just hear me out. Some things don't go together.
Everything has a balance. You are going over kill on somethings, and way under on others.

The well maintained stock na motor last over 200,000 miles. The big parts don't give out, the rings do. It will be the same on your special built motor too.

You should call Corkey Bell and listen to the setup he advises. If you want it dependable for that hp goal. Just put a Greddy kit on your stock motor.
The extra you are thinking of spending would buy several used motors. Or a used Ls1 Camero.
And your probably not going to keep that car 15 yrs anyways.

I just don't get this guy, I think he is missinformed about how a turbo set up works. Someone local take for a ride in a well set up car and have him come to senses, beat him if you have to, I just can't listen to him asking the wrong question over and over, but at the same time I want to help him, but he won't listen.

Low comp+high boost=the win
high compression+low boost=good
low compression+low boost=ok, still slow and inefficient
high compression+high boost=disaster/failure/kaboooooom

Before you waste more money, look into proper management, a built motor is worthless if you are not gonna make use of it, ie. low boost. Why? It makes no freaking sense.

not a good comparison my friend. put up my #5 from the 08 dyno day and do it again. or the 006. or both i dunno.

actually yeah i should have used airbrushes, same turbo more or less....i did it in haste.

no put mine! put my number 5 and 6 or I'll do it myself when I find your run! :D

lolz.

Interesting. Do you have pix on the unshrouding? Where did you get the idea? Do you have flow numbers?

I think this is backwards. For a street car, you want a smallish turbo that meets your power target, in order to get best response and low end.

Off boost torque gains from higher compression is 4% per point of compression ratio, but it doesn't help SPOOLUP. Turbo sizing is a huge factor in spoolup.

This will help spoolup AND off-boost torque.

lolz is the red and blue line up to 3600! heh

This will make Zabac smile. I found the solution to my madness. Use stock engine, get new rings, get headwork done, upgrade to a standalone (Hydra) or parallel (MS) run like 12 psi, keep using my car as a work beater and get better fuel mileage than I do now cause I will have the power to properly tune it, and smile cause it's done.

Very close. Only, why parallel? Do a stand alone MS. Cheaper, works better. Seriously.

Otherwise, you're right on.

As to the dyno pulls, the 1.8 liter is the one who didn't lift at 6k. :-)

:bowrofl::bowrofl::bowrofl::bowrofl::bowrofl::bowr ofl::bowrofl::bowrofl:
Amen brother...now you're talking!!! Proper management is key, the motor is very capable as is, your inability to tune it is what is holding you back right now.
At 12psi, don't waste your money on head work (unless you are doing it yourself and you know what you are doing), it will help, but at that power level there are better places to put your money. Head work becomes more important with bigger power goals as the benefits really start to show then, significantly.
If you will do anything to the motor (if you are planning a rebuild) just plan on some rods and rings and tri-coated stock pistons, you should be fine even at 300 whp then.
Good luck in your build...

Headwork kinda always helps. With my wastegate full open, my car was as fast as a MSM, which I attribute to the headwork. 1 psi vs 8?

I think of it more as the gift that keeps on giving, the more you do the more good it does. 12 PSI on a modern motor is a healthy amount of power - hell, FM says you'll bend rods there, and to only run 9 (on their piggyback kit, admitedly)

But 225 whp on 12 psi is *entirely* reasonable, if not 250, on a '99 with headwork.

FM told me if I get the hydra to fun 12 psi. They said the voodoo won't control over a 1.8 injector, and could only run 9 psi.

Porting heads would be my last consern for your stated goals. You only need that if you are just going to race it out and have it undependable.
Having the head or even valve guides and seals redone for the engine rebuild may not be a bad idea.
You know your budget.
Good luck on the build.

Not dissagreeing there, just for his goals it seems unneccasary to do any head work simply due to the cost involved, that's why I said unless he was doing it himself, but if you are having a reputable builder doing any headwork, especially anything significant, it will cost a whole lot of money. Now if he was serious about making a lot of power then yeah, but then we are talking lots of other things to do as well.

Yeah, ok, I'll give you that. It's a good thing to do (all about efficiency!) but on a budget, don't scrimp on engine management.

I know all the magic of a better flowing head, for all serious power gains it's pretty much a must and it is the only part in my build where I'm willing to drop as much money as needed be to have everything of the best. That's why it's the last thing on my list.

Better flowing head = more air for less pressure = less boost = less heat soak = less backpressure, etc etc. While you're in there, put in some real springs (wish I had! I still might swap them, it's a pretty quick job.), and get a higher redline. All free power! :-P

I guess I'm saying I'd do that long before forged pistons. If the motor's out, and you can get cheap rods, that might be the place to put money.


Forced Induction
EMU
Intercooler
Injectors
Free-flow exhaust (though this can be added later)
Rods
Headwork (below rods because it can be done later)
BOV
water injection
Bigger valves, etc, if cheap headwork first time
upgrade downpipe
upgrade intake mani
upgrade turbo
pistons
Boring/Stroking

Somewhere along the line where you're upgrading stuff, it's time to at least concider a motorswap. :-)

I'm curious what other people think about this list, as far as the order for things. Bang for buck, that is.

I'd swap pistons with water injection. especially since you are going for "efficiency", forged piston while not only stronger (and not necessary for 250hp) are often lighter. That's weight at the end of your recipricating mass.