peejay

I haven't been able to get a STOCK port engine to idle that low reliably! They always preferred 900-1000rpm.

My P-port would comfortably run at 600rpm. It wasn't walk-away-from-the-car "reliable" idle, but carburetion + no intake vacuum is like that. The walk-away threshold was about 1200.

Big streetport = no torque =

Peripheral port = fun starts early =

I have an FC engine in the garage, and some ITBs, and other stuff... maybe I'll join the party Sorry if I can only give you crank HP figures, no chassis dyno.

- Pete (who is putting a sleeveless GSL-SE engine in a car right now... we'll see how it do)

ericgrau

iTrader: (1)

My stock motor idles fine at 750. Most of the time. Slightly rough on hot days, also floods sometimes on hot days (4 times in last 2 years). So gotta figure out what's making it rich some day.

Stock RX-8 puts out up to 195-200wHP. 170-175wHP is the figure for a poorly broken-in, abused, etc. motor. Comes from people whining about the power; thing is the loss of power from a bad break in happens to pistons too.

If large street port power drops off after 8000rpm and RX-8 peaks at 8500rpm, I don't see why people say the side ports supposedly make less power. Seems like they breath more freely. Or really I'm betting a small increase in redline would in fact help on a street port.

Besides that, how about leaning it out, increasing compression and using auxillary injection (water or alcohol injection) to keep it cool and keep it from blowing up? I bet that'd next a rather large chunk right there. I mean people already tune it lean for power but they're risking their motors. This might also let you go further.

And I know the electric superchargers are total bull b/c you can't supply enough amps to power one electrically. But how about an 0.5 psi one? That'd draw 30 amps and increase horsepower by 3%. Every little bit counts. Not NA I know but I don't think it'd have the trouble of a real turbo.

slo

iTrader: (1)

aux injection on an NA???

Not required

ericgrau

iTrader: (1)

Not strictly, no. Certainly not on a stock motor & ECU. But it'd let you run lean and high compression without risking your motor.

sc0rp7

iTrader: (3)

aux injection on a N/A could show slight benefits... There are N/A motors running AI... you still get the effects of cooling the intake charge slightly... When shooting for every little bit, why not?

shm21284

The experience I have is somewhat limited; I'm not an engine testing facility. With that said, I will admit I have had 5 engines that were rebuilt and compression tested along their break in period.

1) There was my 1st 12a (12a with bolt on turbo, 9.4:1 compression), which pulled 85-90 psi compression after about 800 miles of soft break in and around 100 miles of hard driving.

2) The second 12a (N/A, street port 9.4:1) was driven soft for a short while, say 50 miles. I decided to drive it very hard (full throttle up to 6K), and the engine had noticably more and more power each time it was shut down and started. This engine pulled 95 psi after about 800 mi of hard driving.

3) 13b 4 port N/A, 9.7:1, which was built by a friend who has a respectable shop on this forum. This engine was also broken in soft and produced 90 psi of compression for its life in the vehicle.

4) 13b 4 port N/A, 9.4:1, was driven soft for about 500 miles then driven hard. This engine produced 95 psi compression after 800 total miles (300 hard miles).

5) 13b 4 port N/A, 9.0:1 (TURBO ROTORS). We tried a "soft" break-in (low loads up to 4-5k rpm) and the compression only rose from 70psi to 75psi over 450 miles. Then, I decided to beat the hell out of it (WOT up to 8000 RPM) and the compression magically rose from 75psi to 105psi in a matter of 200 more miles.

*All engines listed above used the same starter and same optima battery; starting speed was very similar.

I do believe that there is a such thing as "too hard a break in." There is some middle ground which is optimum (too soft a break in is not the best either), which could or could not be a N/A at full throttle. A turbo at full throttle is too hard on internals and is not ideal.

Is this data admissable to a major engineering firm as hard proof that hard break-ins are desirable? Absolutely not! One would have to test numerous identical engines with identical cranking speads, identical ports, identical seal clearances, identical initial compression numbers, identical atmospheric conditions, and varying loads/rpms with frequent compression tests along the way, all of which I certainly can not perform without a few mil in the bank.

As far as my theory behind the mechanics of the hard break-in? That, I do not feal at liberty to discuss.

rotormind

I was wondering if bridge porting the 5th and 6th port still count in this challenge because iam going to be using the actuators. Dont know if iam going this route but i would like to know how much would this help with power.

GtoRx7

iTrader: (5)

I dont think technically it would count, however I would still like to include them. Simply because I've never seen one on the dyno, or make very high numbers. It would be cool to see how far one could go with this setup fully optimized.

ultimatejay

iTrader: (1)

You know the old saying, " Break it in how your going to drive it."

innesxsenni

250rwhp would be an expesive way to go with 13b.. i think thats why everyone jumps up to turbo or in that case other swaps... if i thought i could hit 250 300 with my n/a motor i proablly wouldnt swap it.......

Roen

iTrader: (2)

You guys should search for threads on Aux Bridging and why it doesn't work with a stock setup and you'd be better served with a full bridge or even a half bridge if you're going to do it at all.

peejay

It's a different kind of power. Naturally asiprated engines all make about the same amount of torque +- about ten-fifteen percent. Turbo engines make a lot more torque, and that kills driveline components, so that is an added expense. For how much it would cost to put a TII transmission in a 1st-gen (no engine yet), you could build several kickass N/A engines.

Automatics can handle the torque, but for some reason automatic is a dirty word in the import community.

rotarygod

iTrader: (1)

Here's where the hard break in information comes from:

http://www.mototuneusa.com/break_in_secrets.htm

Roen

iTrader: (2)

What's your opinion of hard vs. soft?

Does anyone happen to have a corollary between that article and rotary engines? Like a proper method for hard break-ins, with oil change intervals?

dj55b

iTrader: (2)

The one thing that I've always pointed out in this article is this little section:

"Due to the vastly improved metal casting and machining technologies which are now used, tight parts in new engines are not normal. A manufacturing mistake causing a tight clearance is an extremely rare occurrence these days. But, if there is something wrong with the engine clearances from the factory, no amount of gentle running will fix the problem."

In those case I might agree, but you have to remember how long ago have our old 12a's and 13b's been manufatured? How many of us even on a rebuilt engine buy new Housings instead or reusing old ones? How old is the technology used for making stock seals(Newer seals like atkins, NRS, ... exempted), so should we really be doing this? Also the fact that we only have so little moving parts in our cars, and the only things that need to be "seated" in as per say would be bearings, seals, and housing surfaces. Its not that much.

Don49

iTrader: (3)

My engine builder for my 13b SCCA E Prod motor does a six hour break in on the dyno at varying loads and then the motor is ready to go with no additional break in. When I swallowed a screw in #1 rotor, a new rotor and housing were installed. Due to time constraints I had to break it in at the track I ran it in the shop at home for approximately 15 minutes to warm it up and check for leaks. At the track I warmed it up to about 150 degrees and then took a couple moderate laps to get fully to temp. For the remainder of that session and the next 25 minute session I ran it hard, watching my oil and water temps. This was done with Shell Rotella 15w40(better additive package). Then I changed to 50w Redline oil to race. This was on the reccomendation of Jesse Prather, who built the engine. It worked fine and the motor is very strong with no blowby or oil consumption. As a side note, when I was building my own piston engines, I used basically the same technique with great success.

Kyrasis6

When I was working at a shop building NEXTEL Cup engines a "Basic" break in involved preheating the fluids, doing a couple of very light load pulls to get temps up and to verify everything was put together ok. Do all of you're mechanical checks, followed by another warm up pull, then they ran it hard, very hard. One of the dyno guys was told me in the past they have blown engine blocks completely in half from breaking them in so hard and having something let go. I wasn't allowed to know much about the exact procedures we used but the break in "process" was a little different for every track and was constantly being changed because of new materials, different power bands, different tollerances, etc...

I'm still very slowly working on my N/A build, it came to an abrupt hault when I lost my job there. I'm shooting for around 200 rwhp, it was originally an S4 13B N/A but since then I have gotten TII rotor housings and S5 irons and will be putting S5 rotors in it. I originally used a racing beat street port template for the primary intake ports but after some recommendations from some of our cylinder head guys I decided only to use certain parts of the template and focused more on where the air was flowing through the ports. Exhaust, secondaries, and 6-ports where ported free hand. I was in the process of making new 6-port sleeves that where slightly bigger on the ID and used a refined actuating system to eliminate the air obstructions of the stock system. That might never happen now though since I don't have access to the machinery to make the parts. I was going to lighten and ballance the rotational assembly, already have an RX-8 e-shaft. Was going to run tightened apex seal groove clearances with a few tweaks to make it work. The car came with a Racing Beat true dual header I was going to modify, then make a collector bolt up afterwards. There where probably a dozen or two other slight tweaks I was going to make but probably won't be able to try on this engine because once again I don't have free access to the equipment to perform such modifications.

peejay

Well, you also have to figure, that race engines, or even production engines nowadays, have the cylinder bores machined to an almost mirror finish. No more 80 grit crosshatch to "hold in the oil and lap in the rings" type junk. And the rings are low tension, moly faced jobs, that not only like the mirror finishes, they actually require them.

Basically, modern (piston) engines are machined and assembled "broken in". You fire 'em up, let the fluids circulate, make sure it has good oil pressure, no ugly noises, and no leaks. By the time it's warmed up, it's fine to let 'er rip.

A lot of the rotor housing updates Mazda has done over the years has been in the interest of initial break-in. Would a "50 foot break in period" work for FD housings? Probably. Would it work for '74 13B housings? Probably not.

shm21284

I'm not quite sure what you're talking about here, every new engine I've seen in an engine plant, whether it be an ecotec, a detroit diesel, or a new LS-X engine at Wheel 2 Wheel, had a cross-hatch honing to it. The cylinders still need to retain oil for lubrication of the rings...

peejay

There is an ENORMOUS difference between a modern crosshatch and an old-timey one.

Yes there is still a detectible cross-hatch finish, but it is extremely fine. About the same as what you see when you pull the heads off of a 150k mile old engine.

shm21284

I'm not arguing that ther isn't an enormous difference in modern cross hatches vs old timey cross hatches; my point is that it is by no means a mirror finish.

peejay

True enough. It's not literally, optically a mirror finish (heck, even the decks aren't) but it's smooth enough for a ballpoint to draw a line instead of a series of dots.

My stock port 13B much prefers a 1000rpm idle to 800...

arghx

iTrader: (3)

172 rwhp. I did this a couple years ago on my old nonturbo before I sold it. That wideband read a little lean... and you can see like a blank spot on the dyno. In hindsight that dyno really wasn't very good.

now let me see if i can recall my mod list

-- stock ECU with SAFC (had a Zeal Megasquirt later and made similar numbers. I was disappointed). this was long before the Rtek 2.0 was available

-- street ported s4 motor, s4 rotors and manifolds (manifolds were ported)

-- T2 rotor housings I think

-- Pineapple racing 6 port sleeves, wired open. later I ran a 12 volt pump to actuate them with an RPM switch, but it wasn't very reliable because the damn sleeves would stick. Ended up wiring them open again and just saying **** it.

-- RB collected header, straight midpipe, 2.5" RB dual exhaust

-- TB mod, removed ACV and air pump but kept BAC and thermowax

-- ghetto advanced the timing by turning the CAS.

I think the car had another 10-15 rwhp in it if I installed s5 manifolds, but at that point it was just too much bullshit for so little hp. I daily drove that car for 3 years and then sold it to a friend, and now I am in the process of building and tuning a T2 with a decent sized turbo.

Kyrasis6

Moly is obsolete when it comes to rings in the racing industry. Top NASCAR teams now use different materials for each ring and several different coatings. As for the mirror finish the cylinders must be atleast 5 ra to break in and that is if you are using a break in oil.

Either way, if you don't have enough pressure on the "seals" they will never break in properly, this includes rotaries.

peejay

And how it do: No dyno yet (but there will be one but as it is: it idles at 40KPa at 1000rpm, idling lower or driving around town is tricky because my idle PWs are in the 2.0-2.1ms range and my ECU has .1ms resolution. Cruise PWs are in the 1.6-1.7 range Need smaller injectors!

Driving wise it cruises the highway at 45-50KPa and seems really drivable.

Power wise, below 3k it feels weaker than one of my tweaked stock 12As. Between 3k and 6k it kinda "ascends" in torque, far unlike any of my 12As (except for the street port, natch). Then at 6k indicated someone flips a light switch and it grows an extra rotor or something, and it does not feel like it drops off until the end of the tach. I don't feel like winging it that hard so I stop there

So, yes, late closing timing makes for a really peaky engine that is kinda sluggish at the low end... Big shock there.

What IS a shock is that it pulls so hard at the top end with the straw-like GSL-SE intake manifold.

I do not know what my AFRs are at but it doesn't "feel" overly rich or lean. Max duty cycle is 78-80%.