tuning tips for high compression turbo
 

can someone give me a baseline for timing and afr?

right now i just put it in exactly at tdc and locked it down

i tuned afr to around 11.0 to 1 on 91 octane


s4 street ported turbo motor with s5 NA rotors (9.7?) and counterweight

A/R .60 M24 B.O. Garrett boosting 10 lbs

V mounted, 3 inch DP and exhaust

safc 1 , rtek 1.8 (retards timing 1 degree every pound boosted over 9/built in fcd etc.) with 720 injectors all around

aeromotive fpr with ss fuel lines parrallel, walbro 255

plx r 500 wideband/egt/knock controller

im also getting this lean spot at light throttle at 3500.

thanks in advanced

Timing sounds agressive for your set up. I would keep the boost as low as possible until you have a standalone ecu and can create a timing map for your application.

Or take it somewhere get a ECU and have it tuned. If you dont mind going through several motors learning how to tune it then you should be good, but at least get a Microtech or Haltech.

drift monster:
what's the max advance that rtek puts out?

i'm in the same boat as you, but not as far along. i have an S5 6port with stock rotors. (yes they are 9.7:1 PR)

i was planning on running 8-12psi starting low, and adding more depending on how things go.

maybe we can help each other out with this, as many people on these boards will simply tell you that boosting a high compression rotary "is not a good idea" and say nothing more on the subject.

They say that because they are clueless. My suggestion would be to contact Crispeed as he has experience with tuning hi compression turbo rotary's.

Yup, i've tried asking for help on this board on that topic before too, from my experiance I've run about 8deg of timing at 14psi... the only time i dentonated was low boost and cruise RPM's. I think locking it down would give you shitty MPG at cruise and high EGT's at idel.. Oh, i also used 93 octane... but I'd still advance it at least a few deg if i were you.

what are you tuning with?

none of that makes sense... clarify please

from what i know about boosting an NA is the higher compression makes combustion temps hotter which increases the chance of detonation. philiptompkins if your detonating anywhere then you should not recommend timing advice, this is just going to make him detonate like you and blow his shit up. i don't mean to insult anyone, i just don't want the wrong information to be passed and then this guy is out of a car.

since the 1.8 isn't adjustable, i would recommend retarding an additional degree per psi after 9 psi of boost since the rtek 1.X's don't retard enough timing for anything bigger than a stock turbo. your afr's are perfect and safe, 11.0-11.3 is perfect for under boost. a fmic would help lower combustion temps. in addition with the fmic, to make it safest as possible you could buy a water injection kit.

I'm running it with megasquirt.
And your right, higher comp. does make comustion temps hotter and increses the point at which the motor detonates.
To compensate for this it is important to run a few less degrees of timing than your would on the same motor with turbo rotors.
annnd, for you personal attcack on my knowlage: How can you learn how far a motor with a setup that NO ONE has apparently run (or is willing to give advice for) if you don't push it a lil. I told him about my experiance with detonaion to help him not make the same mistake. I was trying to save fuel during highway cruising so I advanced it out quite abit for low RPM (3-3.5k), low boost... and the motor didn't like it... just saying.
And yeah i'm sure the FMIC is a good idea. I just thinkg running 0 deg is a lil too far out on the conservitive side. If i had to lock mine down and run 14psi, i think i'd try somewhere around 8 deg

no attack intended here.

im just very conservative when i give tuning information as some people are very sloppy tuners (not talking about anyone here as i dont know any of you :)). the rtek 1.8 is an ok piggyback for a small turbo and not alot of boost but if im correct, the turbo you described (driftmonster) is the same as my last turbo. it was a to4e hybrid 50 trim which is not a small turbo. my advice is be conservative since you dont have a good way to adjust timing (only manually). until you get a standalone i wouldn't push more than 10 psi with your limited piggyback. timing is as important as afr's, get at least a Rtek 2.1 if cost is limited.

if he wants more power and boost he's gonna have to eventually fork out the money and buy a standalone or equivalent.

i have heard of a way to tune ignition advance without using a knock sensor. i heard it from a piston engine source, but i don't see why it wont work on a rotary. this could be handy if you are running rotors and boost levels that normaly don't go together, and you can't find anyone else that has done your particular set up before.

put a thermal couple in the exhasut to measure EGT. hold the engine at whatever RPM/load you want to tune at. also make note of your IAT, Coolant temp, and what octane gas you are running.

start off with a very moderate advance (something low like 5*BTDC). start giving it more advance while observing EGT.

EGTs should start to drop becasue with a low amount of advance, the fuel does not finish buring until well after the exhasut port opens. as you give it more advance you will get less plasma (fire) coming out of the exhaust and hence EGT's will drop.

as you continue to add advance, EGT's will bottom out as some point. this is the point where you want to stop giving it advance.
if you can't tell when it bottoms out, continue to give it a few more degrees advance until you see EGT's start to rise again. now the EGT's are getting high becasue you are starting to casue the unburnt fuel in front of the flame front to detonate instead of deflagrating like they should. (i can't say from first hand experience as i have not actually done this YET, but i reckon making your motor do this to a small degree won't damage anything). if you were to CONTINUE to give it more advance, you would be deflagrating a smaller percentage of fuel, and detonating a larger portion, which would lead to motor damage eventually. but of course you won't do that...the reason EGTs rise when you start to detonate a portion of your charge is becasue the mechanical system (read: rotor) isn't moving at the appropriate speed to absorb this change in thermal (and hence pressure) energy. the shock wave from detonation travels at the speed of sound in the fluid, much too fast for the rotor to harness. whereas in deflagration (normal engine combustion) the pressure rises smooothly and the pressure front travels with the rotor. thats why EGTs get high when you stat to detonate.

anyway, the point at which your EGT's bottom out should be the sweet spot for your ignition advance. i would guess your typical advance table is based on MAP and RPM alone. you would ideally have some weighting function to tweak this value depending on IAT, CLT and fuel octane number.

please note!!!!
the above strategy this makes sense to me, but i have NOT done this myself yet. i see no reason why this would not work, but proceed at your own risk please.

who wants to be the test subject?? lol :uhh:

that's how i'll be tuning my advance unless i find some better method. the motor mounts are almost done, and after that i just need a custom driveshaft. once that is done we'll be tuning again. i'll let you know how this method goes once we try it.

what should my idle egt?

egt while boosting?

i have a plx and the voltage on the knock sensor sometimes goes to 2 volts. i tried listening to it with head phones and cannot distinguish the "knock"

as far as idle EGT goes, i would assume you could use the same method i described above, just look for the point at which the EGT's bottom out. however i have also read from several different sources that roatries idle best at around 5 deg advance, which has worked pretty well for me in the past. when i was using megasquirt i was ideling at around 14.0:1 AFR and 5 deg advance and i was idleing steady as low as 700rpm. i hear thats a pretty low idle rpm for a rotary, but it's all i've ever known (i've never tuned a rotary using its stock ECU)

i dunno for sure but from what i have read, knock is unrecognizable to the human ear. i think this is a freqency issue, not amplitude. you might be able to run the voltage signal through a computer with a real time pitch shifter lowering the frequency an octave or two, of course using a real time pitch shifter will not preserve the quality of the waveform. a non-real time solution would be to record it and then pitch it down continuously one or two octaves. even then this is just a guess, i have no clue if you will be able to hear it or not.

updatE.... i blew my motor, cracked the rear housing, the car was fine for these past couple months (daily driven and 5 track days) at 6 pounds of boost untill i put on an EBC and raised it to 10 pounds, i should have backed the timing a little more, i was at 10 degees, 10.5 afr and 800*celcius .i thought it was a safe tune, i guess not

anyways, im going to go haltech eventually but for now im thinking of running water injection and backing off the timing to maybe 7 degrees.

is your engine a s5? this is a common problem with s5's. whats even more amazing, mine just cracked today also. it cracked right where the rear iron meets with the rear rotor housing where the dowel pin is.

drift monster said he has an S4 block with S5 rotors. i thought they largely fixed this weak spot when they went from S4 to S5. here comes a dumb question mzrx7man, are you sure you have an S5, becasue '88 is the last year for S4 i'm pretty sure (maybe it was '87), and i see in your sig you have an '88. does your intake manifold have VDI?

drift monster: is your rtek controlling your fuel injection as well? how many squirts per intake stroke do you do? is your injection set to occur at the same time as a spark?
what i'm driving at, is if you got a lean charge becasue of a fuel injection event not fully getting sucked into the chamber. this might be a long shot, but it's the only thing i can think of. i can imagine a potential problem a rotary may encounter since we don't have the luxury of squirting fuel on top of a hot intake valve head, rotaries require a little more attention to be paid to the injection angle.

engine is an s4.

only the later S5 irons came with the reinforcement by the dowel.

safc is the only thing controlling fuel. im pretty sure my timing was just a little agressive and i should have turned up the fuel pressure too

i put a s5 engine in my car. s4 irons are the weakest. s5 irons were slightly reinforced and some s5 irons were reinforced even more, you just have to know what to look for. look at where i learned this.


http://www.rotaryresurrection.com/2n...ron_break.html

I don't understand why you didn't do methanol/water injection . I refuse to run any serious boost (and even 10psi is a decent amount with 9.7:1 compression) on just straight pump gas. I know it's possible to run without it, (Aaron Cake has 9.4:1 rotors on straight pump at 13psi) but if you are a novice tuner it's stupid not to.

i agree, but he didn't ask, and i didn't want to get into a big schpeal about aux. injection.

since you brought it up, i've got a question about water/meth injected engines:
do people typically run their air to fuel ratio just a tad rich of stoich (say 13.5:1), and all that extra fuel you would normally "waste" preventing detonation gets replaced with water/meth, OR do you still pump lots of fuel in (10:1 territory) ON TOP of the water/meth?

i blew the rear housing again! with water injection!

^ Seems to me since you keep blowing engines, you need to get it professionally tuned by someone else. You keep this up and people here will start to come to the conclusion that hi compression rotary's are unreliable.

A real standalone wouldn't hurt either!

What are you doing for ignition? From what I understand, cracking the housings is more of a misfire under heavy load problem.

It's not surprising you are blowing up engines if you are tuning for 10.5 with such little timing. That's just going to create misfires, which is going to make massive chamber pressure the next cycle.

More timing and less fuel is required. At 13 PSI on a GT4088R, I'm running about 11.5:1, 15 degrees, and 9.4:1 rotors. 91 octane. I will be bringing the timing down to 12 degrees by 16 PSI when I do more tuning, and probably 11:1 as well.