Tuning timing - advice?
 

So I'm at a point where I'm tuning timing on a 2.4L 8-valve motor. Forged pistions 8.5:1 CR.
I've got my fuel spot on per LC-1 wideband, but I haven't tuned fuel for a blown setup before and I found that by starting with the same timing map as this motor would have naturally aspirated (when not under boost) my timing was way too low and I had high EGTs that didn't do good things for my turbo (rebuild #2).

The overall question is when tuning timing, how do you know where the limit is? I understand concepts of pulling boost per PSI, etc, but setting that initial 100KPA (no boost) timing point - do you let it detonate and then back off a few degrees?

The only advice I've received off this forum is to "read my plugs" to tune timing... Either that's smoking crack or I'm simply not interested in reading plugs to determine timing...

Re: Tuning timing - advice?
 

Dyno.

Det-cans.

Google?

Re: Tuning timing - advice?
 

yeah..just advance ur timing until u listen when ur car begin detonates..then retard some dregrees

:8

plugs it's good way too for knowing ir u are runing very rich or lean

Re: Tuning timing - advice?
 

You can read the plugs to make sure theirs no detonation to. You need a 10x magnifying glass look for pits in the porcilen and lttle peices of aluminium stuck to it.

the best way is to use a dyno and a det can. then when your done and think theirs no detonation inspect the plugs to make sure.

Re: Tuning timing - advice?
 

If you are not interested in learning to read plugs than you arent interested in learning to tune timing. Simply the best way to know what is going on inside of the combustion chamber is to pull a plug and look at it as it is the only thing you can physically view that is in that combustion chamber during the burn...

Reading plugs and the dyno...only way.

Re: Tuning timing - advice?
 

So you're saying outside of the LC-1 that I've purchased from you, I still need to learn to read the plugs? I've got complete engine logging - boost, timing, A/F, etc.

Adding an EGT and I still need to have a look? Tuning 2-strokes, which I'm familiar with - proper tuning requires a new plug quite often to be able to read it correctly.


Det-can, eh? I hadn't heard of that.. Great concept. I was thinking of buying knocksense, but many posts indicate that the manual method may be better.. thanks for the tip!

Re: Tuning timing - advice?
 

Yes, wideband only measures one part...Air/Fuel. The wideband will really tell you nothing about timing. EGT will get you so far but can give you false readings about your engine timing if the data is interpreted improperly.

What do you think all of those gearheads did back in the day when there wasnt electronics like there is today? They read plugs...

You can actually tell EVERYTHING about what is going on in the cylinder if you really know what you are looking at. I know guys that dont use widebands, knock monitors, etc and they SOLELY use plugs to tune everything (timing & Air/Fuel)

Re: Tuning timing - advice?
 

I understand that old school gearhead read plugs.. And I've done that for "old school" applications myself - like tuning 2-stroke motorcycles or jetskis.

However, I wouldn't be able to tell you the difference in 14.0:1 vs 14.7:1 (or even greater) if I didn't have a wideband.. I also understand *now* based on my own experience running too high EGTs, that I shouldn't just rely on the wideband - but if I had a wideband and an EGT gauge - is there more that can be learned from reading the plugs? How many guys doing dyno tuning as a service pull plugs after each tuning run?

Re: Tuning timing - advice?
 

i THINK reading plugs tell you if you run VERY rich or VERY lean ... i think... it's good to know that but i think with a WB you will be more accurate for to know ur A/F

Re: Tuning timing - advice?
 

Well Walter a wideband is easier to use for less experianced people but reading plugs will tell the whole story you just have to know what your looking at. When I rode dirtbikes all I had to tune the carb with was the butt dyno and reading the plugs.

If a plugs white your lean.If it's dark your rich. if you see wierd looking pits in the porcilen and little flakes of aluminium youve got detonation.

Experiance owns all.If you actually tune a carb by reading the plugs you learn quick and it becomes obvious whats going on. It's not hard.

Re: Tuning timing - advice?
 

i know.. i know.. but ive seen a powerful cars making alot of power tuned with WB..after to read (not completely still) about tuning.. it's very important to tune with WB and not only by reading plugs.. :y you need to get a A/F specific depending what car (sometimes) so... a WB will let you if youare runing 12.5 or 12.8 for instance..that's what i think ..if im wrong then.. sorry :8

Re: Tuning timing - advice?
 

Anyone that is worth anything will...at least everyone I talk to on a regular basis does. I and others will even pull them on the street after a session sometimes...

Re: Tuning timing - advice?
 

for sure, specially if your runnig a hack and msd boost retard, you can tell everything by the plugs and i still pull mine atleast once every two days and change them about every 2-3 weeks (sometimes less)

Re: Tuning timing - advice?
 

Yeah, but I could tell you if you needed to run that rich/lean based on how the plug looks.

Re: Tuning timing - advice?
 

I met a guy who could guesstimate with .5 AFR just by looking at the plug. I called bullshit, did a pull in the car I was tuning and pulled a plug I was at about 11.0-11.3 during the pull and after looking at it for about a half second he said 11.5-12.0, he knew nothing about the car, being his forte was domestics so needless to say I was impressed and got a bunch of other free advice while i was there :)

Re: Tuning timing - advice?
 

There might be some small cues in the well and on the outside ring I don't know to look for, but the ceramic and ground strap looks more or less identical for anything well-tuned at WOT, from my 13.8:1 AFR B7 to a 500 whp 11.8-12.0:1 car.

Re: Tuning timing - advice?
 

Re: Tuning timing - advice?
 

I told you man, and you thought I was smoking crack ::)

Re: Tuning timing - advice?
 

This might be off topic but I saw a site posted on here about certain plugs under certain condition. Can some post this link up if you have it. Pictures tell a thousand words...

Re: Tuning timing - advice?
 

Ummmm Det cans anyone????

Re: Tuning timing - advice?
 

Re: Tuning timing - advice?
 

hate to do it (because its honda-tech) , but http://www.honda-tech.com/zerothread?id=1555006&page=1



you should check this out too http://autospeed.drive.com.au/cms/article.html?&A=0353

Re: Tuning timing - advice?
 

12:1 or whatever number your aiming for is not the magic fuel ratio for any car. each car is going to be different yours mite like the 12:1 mine may like 11:1. the wide band just shows how much fule there is. reading the plug will tell you what the engine needs. i think this is misunderstood and alot of people just gun for a 12:1 or whatever ration there told to gun for. the wideband is a great aid for tuning a car since you can get an idea of how the cars running during the entire pull not just where it stoped at and tune out the rich/lean spots. i believe the best way is to use both methods but ultimatly only the plug will tell the whole story. im not a mad tuna but thats how i understand it after i was schooled by an old school dsm guy.

Re: Tuning timing - advice?
 

http://cgi.ebay.com/WHISPER-2000-PERSONAL-AMPLIFICATION-SYSTEM-MIB_W0QQitemZ260102410558QQihZ016QQcategoryZ294QQs sPageNameZWDVWQQrdZ1QQcmdZViewItem

If i didnt just by some ear muffs i would try that ----!

Re: Tuning timing - advice?
 

Meh, yes and no. Wideband only reads indicated AFRs, not exact ones. There is a lot that throws off readings.

If you have a precise enough wideband and nothing is wrong with your tuning setup such as exhaust leaks or electrical grounds, then past 11.5:1 on a liquid cooled engine is typically a waste of time. A lot of engines with weak ignitions will misfire in the 11's. Aircooled you normally shoot for mid-10's. A lot of it depends on how much cylinder pressure you have. On that note, I'd like to state that extremely small bore engines like the D16 you can run super rich and the engine likes it with no misfires or loss of power... I've repeated the phenomena where you take out timing and coolant temperatures drop while power increases, and B-series or H-series taken to the point you have a uselessly large amount of power don't do this. The 248 whp (mustang) @ 12 psi was in the mid-11's, you can't make any power on a K-series at that AFR.

But, yeah, plugs! The more I read them the more I love them. It's such a black art, and the sort of camera that would take good pictures of a tiny spark plug tip is about 27th on my list of things to buy. Hrm, with the grand I'm getting back from the gummint for pursuiing my higher education I might buy a camera and rig a magnifying fixture to snap picutres of plugs. It'd be a nice writeup.

Re: Tuning timing - advice?
 

Joseph, why would an exhaust leak make a difference? AFR is simply an air to fuel ratio correct? So the actually leaking of exhaust is not a problem as the ratio will remain the same unless you add air or lose exhaust, and since the air/exhaust is homogeneous mixture, the exhaust and the air is leaking not just the exhaust. Now the only thing I can think of is air being drawn into the exhaust stream. I can't really see that happening either, so if you could explain it to me that would be great, but I really can't see how an exhaust leak will change the wideband's reading in any significant manner.

Re: Tuning timing - advice?
 

Widebands don't read AFRs in the chamber, they read exhaust oxygen content. Due to the pulsation of exhaust gas, it is possible for a crack in the exhaust to throw off wideband readings. Generally speaking, a small hole will only throw off readings at idle (no pressure), but I'm what they call a high tone ---- son of a bitch and I don't ---- around. Most everything I've seen that leaked got a lot worse real quick - fix the car, it's a waste of my time to deal with it.

Even if there is significant pressure in the exhaust, and if the flow dynamics and the crack are just right, then Bernoulli's Law goes into full effect. Think venturis. Think pitot tubes. Think slashcuts in the downpipe for crankcase ventilation. Think erroneous sensor readings and bottom end fuckage. :-\

Re: Tuning timing - advice?
 

We could get incredibly ---- with this if we want. At the point where the exhaust velocity reaches high enough speeds to draw air in from the outside through the crack, it is no longer an exhaust leak. So what is it?

Re: Tuning timing - advice?
 

It's fucked up is what it is. ;)

Re: Tuning timing - advice?
 

---- yeah These are all things Ive been learning for myself lately. Seeing you say it reassures me that I know what I'm doing. It's true with plugs Ive been pulling mine a lot when I'm tuning it really lets you know whats going on. It's funny when I'd rejet my dirtbikes I'd pull plugs and read them all the time and Ive only in the past month been doing it with my car.

Ive got a question though. Do little black specks on fairly clean porclin meen detonation?

Re: Tuning timing - advice?
 

Well ---- JD...hurry up and buy that camera ;D I've never really seen much on tuning by plugs, and this is something I want/need to learn. The most I've ever gotten is black is too rich or oil burning, white is too lean, tan is good, but brown is better on boosted cars. :P I want to see color differences vs. AFR's type of thing, not just a generalization that most articels have. :)

Re: Tuning timing - advice?
 

I typically deal with fresh plugs, the ceramic is clean and any residues are very obvious.

Re: Tuning timing - advice?
 

*L* sorry about that walked away and fogot what I was doing and clicked post when I came back.

Re: Tuning timing - advice?
 

I can understand that as far as detonation is concerned. I guess the best way for me to learn is to get a wideband and compare plugs to the afr reading. Obviously I would think the lighter the color the leaner the mixture. Next step would be to find an old straight back road and do a 3rd gear pull, shut the car off at the top of the run and pull over to see. It would be really nice to tune this basemap for a change now that my car is back in 1 piece ;D

Re: Tuning timing - advice?
 

With pump gas I try for soot in the well, clean white ceramic, and a perfectly centered heat band on the bend of the ground strap. If your part throttle AFRs are correct then the soot in the well only comes from WOT, cars run pretty good.

If using racegas it can color the ceramic a little bit. Which brand and which octane for a given brand changes stuff around a bit. Torco 110 typically leaves ceramic looking like plug 12 in the NGK pamphlet posted above when everything is groovy, VP 116 burns clean but looks similar to plug 12 when you start to glaze it from too-rich WOT AFRs. VP 116 is also a trip, when you tear off the turbo manifold there is fine grey soot, not as thickly layered as the black gasoline soot.

I could talk all freaking day. I have to go look at a dyno with the BRMS boys, and then Pinks. More after the weekend.

Re: Tuning timing - advice?
 

Plug reading is a great way of see what is happening in the hole. Widebands are great tool for getting it prefect. Use both and some dyno time you will be where she is running great.

Randy
PS We dynoed the motor that won the SCCA trans am championship in 1978 HAHAH It has been sitting for 25 years. It had a great air-fuel curve. We tried putting 2 more degree of timming in it, rattled. Those boys had plug reading down!!!

Re: Tuning timing - advice?
 

The more I pull my plugs out and look at the little changes I do to my fuel maps, the more small differences I'm starting to notice. I really wish my camera would take a good pic of them or I'd post them up to see. The wells have all the soot buildup, but the porcelin is still pretty clean (starting to turn almost an off white color now just because it actually seemed to run even better with a few percent more fuel than when I started) but the ground strap has a nice brown tint to it. I added a hair more fuel and it turned a hair darker, but it runs a bit better this way as well. I also ended up pulling out a few degrees of timing under wot full boost (even though it isn't detonating), just for the fact I noticed yesterday in 4th gear on the highway my temp guage started raising up a few degrees. Pulled a few degrees out, added a hair more fuel and now the temp gauge actually drops a hair (only about 5 degrees but I still thought it was strange).

Re: Tuning timing - advice?
 

Yup, exactly.

Re: Tuning timing - advice?
 

i was just looking at the spark plug chart :
http://www.dansmc.com/Spark_Plugs/Sp...s_catalog.html

and comparing number 14 which is "the best" to number 17 which is still labeled as best im just so confused. at number 17 what are all the little flakes of light color material?

-Luke