turbo10th

iTrader: (6)

475rwhp, numerous(like 12 or so) 10sec passes(plus others), ac ps full interior ect, dd when i want to, many 100+mile trips, with 12k(over a year) or so on the build and counting . Its a streetported 13brew with a 61mm BW turbo, fueling, power fc, stock drivetrain, and junk in my 93 FD. Think meth injection awesome and we should start seeing alot more builds with more horsepower with injection lasting longer.

t-von

iTrader: (8)

This doesn't make since to me. I understand the density difference with colder weather but, why wouldn't the air temp correction maps not take care of the changes? Are people just not setting these up properly? I'm just learning the tuning thing with my 20b and I see all these correction maps on my Haltech. For the life of me I just don't understand why anyone who is tuning an engine, isn't using all the available correction features. Do they not work as advertised?

KKMpunkrock2011

iTrader: (5)

they work, its just sometimes you can't set them up during a tuning session and people forget that as ambient temps drop, you have to adjust the fuel tables for colder temps, I probably spent an hour or so doing highway pulls with the air temps in the 40F range just to adjust those tables. Its easy to forget about them.

arghx

iTrader: (3)

It's a lot of work to get them right. Boost control fluctuates with the weather as well, and that also causes problems. Without checking your tune literally as each season changes, you can only make educated guesses as to what would be "optimal" correction factors on each engine. I use the term "optimal" in quotes because a tune will always fluctuate with the weather. You just have to get it to fluctuate within an acceptable range of variation, and people have different ideas about that.

Often the people who have the least problems with tuning fluctuations are the people who are adjusting their correction tables themselves as weather changes. When you pay someone to tune your car they do the best they can given the testing conditions and amount of time available. My AFR's will run as rich as about 10.8:1 when the motor is running hot in the summer and about as lean as 11.3:1 in the winter. I set it up that way intentionally. These standalones still aren't "learning" computers like something you would find on a modern car.

TRWeiss1

iTrader: (20)

Me too. Is it in fact fuel cut though? Wouldn't ignition cut make more sense? If you cut fuel you'd create an even leaner condition during an overboost, which would make detonation more probable...or am I not looking at this the right way?

arghx

iTrader: (3)

Without a doubt.

That's not a direct feature of the PFC, and all the OEM's use fuel cut. Maybe they know something we don't? Some people have built PFC maps that greatly retard timing in the event of an overboost. PM Sandro about that. The fuel cut is built into the PFC "boost" menu on the commander, so it's a lot more convenient to adjust it that way rather than having to load different maps. I also use the PFC to control boost so everything is integrated into the Commander for me.

I think that's the big myth everyone's been believing for too long--that fuel cut is the same as running lean under heavy load. Clearly it's not, and that's why I'd rather hit fuel cut 10 times than overboost once. If it were, it wouldn't be used universally by OEM's to protect engines in the event of an overboost. The FD and FC have it from the factory, and it is based on the pressure sensor reading. All the Subarus have it, and it is based on the pressure sensor reading. The Mitsus (DSM, Vr-4, most Evos) don't have a pressure sensor so they hit fuel cut if the airflow sensor is overrun.

I tune Legacy and STi. If you tell a Subaru tuner that fuel cut blows engines, they'll probably be like "huh?" On those cars, when you overboost enough it cuts fuel and throws a check engine light. So many engines have been saved by this... people throw a full catless exhaust on a WRX and with the stock restricter pill (most turbo cars have restricter pills for the factory solenoid) it overboosts.

TRWeiss1

iTrader: (20)

^ Gotcha. Thanks for the clarification. I used to control boost via the PFC as well, back when I had my Apexi solenoid. It's a shame that it started malfunctioning at higher boost levels. I can't complain too much about the Blitz i-D spec R dual solenoid though. Regardless of the temperature/conditions it holds boost as solid as a rock.

arghx

iTrader: (3)

I'm running the OEM FD 2 port wastegate solenoid on a Tial external gate with some creative plumbing... haven't had any problems for the past year. I run it at about 50% duty.

RotaryEvolution

iTrader: (30)

i havent touched my maps in about 3 years and i don't run a wideband in the car but it is safer to monitor your AFRs while driving to make sure nothing has changed, like a bad tank of gas.

i don't monitor my AFRs or retune regularly because i am an engine builder and i don't mind rebuilding the engine if something does happen to it, it is also as simplified as can possibly be and only takes about 2 hours to yank the motor out and a day to rebuild it and drop it back in.

either monitor your AFRs on your own or have the car retuned at the start of each winter(sometimes an investment is worth it to save you from spending thousands on a new motor after a few years, if you have a good tuner they won't charge you that much for a touch up of the maps). winter time is the death time for rotaries as colder more condensed air increases boost levels and fuel system inadequecies start to show up. fuel filters get dirty, injectors start to lose their flow balance and wiring voltage starts to change with older wiring as the system starts to fail slowly.

j9fd3s

iTrader: (3)

colder air is denser, so it will make more power due to higher oxygen content.

http://en.wikipedia.org/wiki/Air_density

sounds dumb, but a friend of mine used to final tune the carb (this was a LONG time ago, before "tuners" and widebands) he used to final tune the carb on the coldest night of the year.

compared to that every other condition the tune up should be rich...

with EFI though, the fact that you CAN tune for summer and winter means you should take advantage of that

mdpalmer

iTrader: (24)

[QUOTE=Karack;10258302i don't monitor my AFRs or retune regularly because i am an engine builder and i don't mind rebuilding the engine if something does happen to it, it is also as simplified as can possibly be and only takes about 2 hours to yank the motor out and a day to rebuild it and drop it back in.[/QUOTE]

^^ damn. that's awesome. wish I could do that.

DrFelixFig

A little off-topic. But how tough is it to do your own rebuild? I've built plenty of piston engines, two and four-stroke, car, motorcycle, boat, etc. I know this is not really an answerable questions, but if I've got the skillz to rebuild DOHC car engines a rotary should not be outside the realm of my capability??

Guess I could thumb through my FD FSM and see, but I guess I'm just wondering if some piston builders have any reports of their first rotary rebuild experience?

arghx

iTrader: (3)

The first motor I ever built was a rotary. If you've actually built a piston engine before it will be a cinch as long as you can stay organized and get everything very very clean. Things that are normally a concern on piston engines, like degreeing cams and setting bearing clearances, are just not issues. For example, you don't have to set piston-to-wall clearance. You don't have to set bearing clearances for most builds (there are hardly any bearings anyway). The oil pump is just like a typical trochoid pump you'd see on a piston engine. You don't have to adjust valves or degree cams. If you can port a cylinder head you can port a rotary, and the ports on the rotary also have the same function as the cam(s) on a piston motor so that simplifies things further.

For a typical rebuild all you need is a stand adapter for a rotary, a dial indicator, a dial caliper, and a set of feeler gauges. Technically you need micrometers for certain inspection procedures but in practice you don't really need them for most builds. In the worst case scenario you have to go get some bearings pressed. Probably the hardest thing to do on a typical build is clearance the side seals, which is a tedious process like filing piston rings. As long as you are using quality parts, the biggest things people have trouble with are coolant seal installation (didn't clean the grooves properly), side seals (didn't clearance them properly), thrust bearing problems (did not set eccentric shaft endplay properly).

check out www.rebuildingrotaryengines.com for videos. You can also buy a rebuild DVD (I like the one from Bruce Turrentine), read the factory service manual, and search on the forums here. There's a TON of information available.

pyro_racer_0016

i make 320 on low boost and just over 400 on high and i am on a stock mazda reman and have been for a few years however i am running a vmount and its a steve kan tuned car.

DrFelixFig

Thanks Arghx,

I figured as much; and sometimes when someone asks the question "can I" sort of gives the answer, in so far as, if you're asking you probably cannot.

They seem like you'd need a few special tools but from what you've said it sounds like almost not at all.

If the motor is in decent shape, housings and whatnot, and you just replace say the apex seals and gaskets, side seals and whatever wear-ables, how much would a rebuild run in a best case scenario? Moreover, it sounds like machine shop work is not needed huh?

Impressive...how many miles on it? And do you usually run at low boost?

j9fd3s

iTrader: (3)

prices change, but an OEM set of ALL the seals and gaskets is in the $1000-1200 range depending on the deal you can get, and the yen/dollar ratio. non OEM parts are generally inferior

machine shop work is not needed. except maybe pressing new bearings. which makes these engines ever more garage build friendly.

KKMpunkrock2011

iTrader: (5)

I would like to say that if you're going for as cheap of a rebuild as possible, if your side seals are reusable and the apex seals on one of the rotors are still good, there's no need to replace them. It's recommended and it will help the life of your motor, but its not needed. Thats what I plan on doing on my rebuild, the front rotor has 120-125 psi on all faces so I know she's in good shape.