we have been severely lacking in some tech here so here we go

through much of my own debate i wanted to start a discussion here to see if people go through the time to do this during their tuning process. I made a post in my build thread and im just going to copy and paste:

http://bbmoto.net/wiki/index.php?Tot...derEquilibrium

"well not all cylinders are going to be as efficient as the rest. Some will combust perfectly and another may detonate. Reading the spark plugs is the simplest and quickest way to adjust individual cylinder trims for fuel and ignition. I haven't quite gotten the eye for reading the fuel yet, but im slowly learning that part. Ideally you would want to have EGT probes on each exhaust runner primary and the cool hip spark plug adapters which can log cylinder pressure. Match EGT's and cylinder pressure and you essentially have 4 equivalent cylinders.

This is all about pulse tuning and getting each one as similar to the one in front of it and coming up behind it. I mean it makes sense. Think about the point of a merge collector with equal length runners. Do you really think that each pulse has the same velocity behind it as the others in front and behind it? You are going to have varying velocities which are going to interrupt each other and decrease the value of the header.

Say you have one pulse going through the collector moving really fast and one behind it moving slower. Then the pulse behind the slower one moving faster. They enter the collector at the wrong times and the low pressure which you are trying to achieve that sucks the following pulse through the collector is hindered and you lose velocity and engine efficiency. Basically you are creating turbulence. IMO compression testers can be really good predictors of the differences in which each cylinder is going to differ but i don't have any evidence to back that up."

 

I was just thinking about this type of thing. Since people go through so much trouble to make sure everything is balanced internally in terms of mass, why don't you hear more about people doing everything they can to make sure that each cylinder is tuned individually so that you're getting the most available energy out of the engine. unfortunately I dont have any real world experience here but i like the sounds of this topic.

 

It makes me wonder A LOT whether other tuners are doing this. I have done it with my car (partially) and i can tell you that it makes a big difference even though i have only partially tuned the individual cylinders. It takes up a lot of time which is why i can see the point in why some tuners dont take the time to do it. However, i am wondering what some of the "higher ups" really do with the 8xx whp turbo motors. I know that many of the drag engines will make that power without having to do individual cylinder tuning.

I am by no means an expert at reading a spark plug, yet, but I do know that while I was tuning my motor (12.2:1 h23vtec on pump gas) the engine wanted 3.5* taken out of cylinder 3 (hottest cylinder) and 3* taken out of cylinder 4. cylinder 1 took the least amount out at .50. Each time i would take out timing from 3 and 4 the power would drop and the graph would get all messy indicating that its either missing or you are running to little ignition. Well i know it was not missing and there was absolutely ZERO detonation. I would add a degree back to the table and the power would jump back up and over the previous run before it lost power. I'm running almost 30* of actual timing to the engine and shows zero signs of detonation.

(and btw, i am fully aware that not all engine managements are capable of adjusting individual cylinder trim for either fuel or ignition or both. Or if they do have it, whether it actually works)

 

If your going to tune each cylinder individually, isnt that the whole point of running an ITB's system.

 

no. ITB's do not "tune" an engine.

 

It is about time someone brought this up on here. There use to be a site few years ago that explained this really well. I tanked bout a year ago. Really wish I would have copied pages for future reference.

 

Thanks captian obvious. Im well aware of that, but it makes tuning an AF ratio for each cylinder easier. Thats what I was saying.

 

why would it make it easier? Just because the cylinders now have the ability to bring in the same amount of air (when setup properly) does not necessarily mean it makes the process of tuning the cylinders individually easier nor does it mean that the cylinders will be any more efficient at combusting the mix to the extent of requiring less tuning time in that area. Too many variables there to make that assumption. You still have to go through the same process. Not to mention that you have to make sure the throttle plates are synced correctly and the tools to do that are not exactly cheap or abundant.

If you are tuning ITB's blindly (by not syncing the throttles together), you are likely making it harder to properly tune each individual cylinder and will likely require changes near the extremes to combat the difference in flow between the cylinders.

 

Heres where the whole Vaccum effect comes in. You say each pulse coming through the collector. Well isnt it vaccumed out of the combustion chamber. As for turbulance, of course there will be some, you are creating thousands of explusions a minute.

Take a look at a rocket ship on take off. Those exhuast pipes would burn up small towns, and they have tons of turbluance. :p

If you really want to tune each cylinder accordingly, now this is all theroy and not proven, but would 4 AF gauges, one located in each exhaust port let you monitor each cylider 4 times better Vs 1 AF gauge in the down pipe. That way you could make each adjustment properly to the fuel injector. And having an ITB, you would also have better manuiplation of the air ammount in each cylinder.

 

for individual fuel tuning yes, but not for ignition.

 

The vacuum effect your mentioning is called scavenging, correct? I think 98vtec is talking about tuning each cylinder to improve the scavenging effect of a well built header.

I follow your idea of having 4 widebands, one for each cylinder. 98vtec mentioned 4 EGT sensors for a similar purpose.

what I'm not following is how you manipulate the amount of air in each cylinder individually, even with ITBs? It was my understanding that they are suppposed to be synced so that each cylinder's butterfly opens the same. That way you have the same amount of air entering each cylinder.

You then tune the fuel to correct for minor inherent differences between cylinders (the topic of this thread). That's where the 4 widebands you brought up or the 4 EGT sensors 98vtec brought up come in to play.

I've never heard of anyone tuning the amount of air coming into a motor to match the amount of fuel being delivered, which is how I'm interpreting your comment on manipulating ITBs. That just seems backwards to me, but please correct me if I'm misunderstanding you.

 

that is exactly what i am referring to. Not only a header, a equal length turbo manifold will share the same effect just with higher velocities.

and i was a bit confused on the manipulation part as well.

 

i wanted to come back and comment on this. The vacuum effect aka scavenging is created through the use of merge collectors and designing a header with the proper lengths. The pulse enters the collector and the low pressure aka vacuum sucks it through the collector which increases the exhaust velocity. BUT this will only happen if everything is timed correctly and the cylinders are working with each other and not against.
the pulse is not sucked out of the combustion chamber. The piston pushes the burnt mixture out of the combustion chamber via exhaust valve.

What you may be getting confused with is the small amount of overlap when the exhaust valve is closing the and intake valve is opening. This little amount of time both of them are open can help clear the combustion chamber by creating an area of low pressure and "sucking" the remainder of the unburnt gases which were left over from the exhaust cycle out of the exhaust valve before it closes and thus the following intake and combustion event will be cleaner.

 

That small ammount of unburnt gas.

If your leaving a small ammount of unburnt gas in the chamber, wouldnt you want to tune it a little more. I relaize that is always a little good to run a tad rich in the chambers.

If you want a cleaner combustion, why not use a higher grade of gas, something that burns faster, and wont be left unburnt in the chamber.

I also understand that you are trying to run your header for a better flow, but why not just get rid of the down pipe and have other pipes that are built to flow out the sides of your bumper.

Something like 1 pipe for each header. Of course it would be extremly loud because there is no muffler or resonator, and it would poplute the atmosphere more, but atleast this way you wouldnt have to worry about the other cylinders getting in the way of each other.

 

there is always going to be wasted fuel regardless of the octane or what you do with tuning but you can aid in making it better. Higher octane gas burns slower to keep the fuel from burning up prematurely. You are naming all the variables but you need to remember that race gas is not cheap and side exit exhausts are not legal and having 4 individual pipes would be deleting the use of a merge collector and completely defeating the purpose of scavenging.
you are taking exhaust dynamics and flipping it completely upside down and having a beer with it, lol.

 

Sometimes I find that the awnser outside the box turns out to be the simplest solutions sometimes. Just a thought.

Other than 4 AF gauges, or a single pipe for each exhuast port, thats pretty much my take on that.

 

its great that you are thinking outside the box, but you dont make 3000hp running nitromethane.

 

I was just saying....

Are you planning on making 3000hp anytime soon.

 

its not even possible with our motors. You are talking about aftermarket parts and this thread is about tuning via engine management. Please stay on topic.

 

Just askin questions from your own posts.

 

Nice topic I hope to see some creative input to help me out.

I am planning on fine tuning my engine via the individual cylinder method. I already have 2 WB o2 sensors & 2 EGT sensors. Ant the Innovate LM3 Auxbox & TC-4 thermocoupler amplifier.

When I do up my exhaust I will be putting an O2 sensor bung and an EGT sensor bung in there respective positions on each primary tube . It will take more time this way but I don't have the money to buy 4 of each of the sensors. I figure once I get it running I can take my time fine tuning the individual cylinder trims via AFRs and EGTs. I would think that there is a bit of an added bonus having fully adjustable ITBs. I'm sure they will help equal the air intake into the engine vs a plenum.

I know all of this would probably be easier with the AEM EMS but I am going to give it a shot with eCtune & LogWorks2.

 

If you are using an EGT probe in each primary, can't you use a combination (and threshold valve) of EGT and A/F ratio to get in the ballpark for ignition trimming per cylinder? I suppose it would require a wideband bung in each runner as well, since you'd have a pretty large window to adjust a single cylinder before it throws the mixture at the collector off. Balancing the flow/burn for each cylinder certainly has merit....F1 tuners use it constantly....

 

I'm tuning via eCtune so you shouldnt have any problems as long as you know what you are doing. good luck

 

well yes and no. A gauge will only tell you so much. I am a firm believer in reading the spark plugs. They are tattletales of your motor and can tell you much more than a gauge.

 

Thanks

I noticed as soon as I bought eCtune that it had individual cylinder trims for both fuel and ignition. That is pretty sweet I'm sure I'll have some fun with it.

Cheers