Hyundai Tiburon Forums banner

1 - 18 of 18 Posts

·
Registered
Joined
·
45 Posts
Discussion Starter #1
Hi, just want to find out from the boosted guys here, what AFR would you say is too rich?

I've been tuning my car with a DET3 piggyback and have worked my way up to ~12 psi and have found that the car pull very well at AFR 10.5 - 11 but just a bit worried as I've heard horror stories of bore wash and soaking the oil with gas.

I've seen from other threads here that guys generally run late 11's to early 12's

I'm running a Evo TD05 turbo & manifold with a stock 2.0L Beta 2 engine so knock limited hence the rich mixture.

Am I worrying too much about this! :)
 

·
Registered
Joined
·
7,978 Posts
My answer is "It Depends". If your engine is 100% stock with stock compression ratio then 11 to 10.5 is not too rich. Any leaner and you will detonate as you have probably found out. You should also be monitoring EGT not just AFR. EGT will show you how hot your exhaust is which is a better indication of how your AFR is affecting things. An as long as your not spitting out fuel from the tail pipe and your oil doesn't smell like gas your fine.
 

·
Registered
Joined
·
45 Posts
Discussion Starter #3
Yup unopened stock engine, dont "think" I had detonation, hard to say without det cans but the only thing I noticed is it doesn't pull as well if I go a bit leaner - say 11.5

I'm have my TPS at full throttle in boost so not sure what the timing is but from what I've read here the stock ecu will retard the timing but I have no idea how much.

Oh I'm also only running Shell V power 99 octane (UK RON)

I have no way of checking my EGT, are there any symptoms of too hot EGT's ? Checked the exhaust manifold after a big pull and wasn't red hot or anything like that. I do think my LSU 4.9 wideband is on its way out as it does go full lean occasionally after a big pull (heat?) its about 3 years old and to be fair its taken a beating! haha

No fuel being spat out the exhaust or black smoke, absolutely nothing actually (166k miles on this engine!!)- I've checked with a gopro! :)

I changed my oil this last weekend as it did smell of fuel but its been in there about 4 months with me tinkering with different AFR's (very rich sometimes at lower rpm) and found my pcv valve was clogged up so no blowby has been extracted which won't help!!
 

·
Registered
Joined
·
7,978 Posts
If your forcing open loop under boost, which is smart, your timing should be good up to about 15psi on 91 octane which is less than your 99 RON. You should really be datalogging your runs using OBD to see what's going on. Its not the most accurate but it should help. What are you clamping your MAF voltage to in the DET3 and is your MAF sensor hopefully in the turbo intake pipe and not in the charge pipe?
 

·
Registered
Joined
·
45 Posts
Discussion Starter #5
Yeah have tried datalogging through Torque but had mixed results due to the tables not lining up properly but I'll give it another go tomorrow to see what timing I running.

MAF is on the turbo intake and clamped to 4.3v
 

·
Registered
Joined
·
45 Posts
Discussion Starter #7
MAF placement was strongly recommended here at NT so thought prob best to do it that way.

MAF voltage was a bit of trial and error, the stock ecu doesn't like any more than that and I haven't had any high voltage codes since so it seems happy. I had missfires at one point and I thought it could have been MAF voltage too high but turned out to be spark gap too big.

Sent from my SM-G930F using Tapatalk
 

·
Registered
Joined
·
45 Posts
Discussion Starter #8
What plug gap you guys running at about 12-15 psi? I'm on about 0.8mm but think I need to go smaller as I on some odd occasions have a missfire for no reason.

Sent from my SM-G930F using Tapatalk
 

·
Registered
Joined
·
7,978 Posts
Are you running colder plugs? Its hard to say what is causing random misfires without more information. Things I look at are AFR, EGT, Intake Temp, Coolant Temp and Ignition timing. The problem with your set up is you don't know your timing when the misfire happens and you intake temp sensor is part of the MAF so its not reading the temp of the air in the intake manifold. I'd put a GM Intake Temp sensor in your manifold and wire it into the DET3 so you can at least capture correct intake temps. Then you could even tune based on those temps as well. ;)
 

·
Registered
Joined
·
45 Posts
Discussion Starter #10
Yeah I'm two heat ranges lower, heat range 7 instead of the stock 5

Unfortunately the Det3 doesn't have enough inputs for me to log any more but I do have a spare SMT7 which I could hook up just for logging extra temp sensors...not ideal but will work!
 

·
Registered
Joined
·
7,978 Posts
OEM Head studs are just fine for lots of power. I'd say about 400whp. :)

Something you have to be careful about is running too cold of a plug. Combustion needs heat to work properly, pull too much out and its possible to get rich misfires and fouled plugs. On my old 2.0 Turbo I ran a MSD DIS2 Ignition amplifier with stock heat range Iridiums. Never had any issues.
 

·
Registered
Joined
·
45 Posts
Discussion Starter #14
Sooo...

Checked and regapped my plugs today, looks like I set them to 0.91mm (0.036") before so I have now set them to 0.82mm (0.032")

Boosted a bit on the way home from work and no missfire YET.

Also logged my timing with Torque and it looks ok - it seems to vary from about 9 to 12 degrees (hard to say exactly as the data is a bit crap)

Took some pics of my plugs while they were out


Sent from my SM-G930F using Tapatalk
 

·
Registered
Joined
·
45 Posts
Discussion Starter #16
Current intercooler size is 550x140x65mm 2.25" in/out

I have bought another one that is 550x 225x65mm and 2.5" in/out that just needs fitting.
20180623_180329.jpg


Sent from my SM-G930F using Tapatalk
 
1 - 18 of 18 Posts
Top