https://ls1tech.com/forums/showthrea...60#post4885460

Ricky

 

my opinion on this, is that the #7 air comes from the last runner all the way in the back. now doing HVAC, my life is air, and i know forcing air into anything and hitting the end that spot gets the most air.
now that said, #7 gets the most air which mixes fueldifferent then all the other cylenders thus making it be the "bad One"
also, being under the cowl im sure adds a little extra heat also.

just an opinion.

 

honestly i have no idea what your asking...talking about...etc...the answer is usually 6 maybe 7. My best guess.

 

So if that hole is getting more air, then it needs more fuel. Meaning a larger injector.

Ricky

 

correct, or what i do is bump #7 up 2 jets, so say im running a 24 in all my fuel side i will bump 7 up to a 26.

 

again, this is not facts, its my thought on the issue. it hasnt been proven ther mith busters or anything

 

Well what I am getting at is I keep here that #7 cylinder is the one that give the most trouble with getting hurt. Well if it is getting hurt beauce of being lean, why do not people just install a large injector in that one hole. Kind of along the line of a direct port, tune per cylinder, get the egt's close to the same. just a chit chatting.

Ricky

 

its a good idea if its possable to tune with it?

im no tuner, so i dont know, it may be real easy

 

May not even need a larger injector if you can tune each individual cylinder ie FAST, BS3, DFI....etc. Just richen up #7 about 5-10% more than the rest. EGT it as well.

 

As of right now there's no way to tune individual injectors with the stock programming (unless I've overlooked something). Maybe HPTuners can integrate something similar to what the GTP programming uses with Injector Skew?

I've attached a screenshot of a GTP bin with Injector skew (open), compared to a 2000 SD Enhanced bin just for reference sake.

 

I was thinking more along the line of the stock PCM, FJO 341B does that individual cylinder tuning for both timing and fuel.
Ricky

 

It would be interesting to talk to one of the big LSx tuners like Katech/LPE who uses 8 widebands on the engine dyno to see the differences. I thought Katech had an engine dyno video where they were using 8 WBs.

 

Ricky, on most NA cars #7 wont be a problem. Its when you move well beyond that .76g/ces of airflow, either by Nitrous/FI, you start seeing 1.05g/sec etc and things start going downhill. I do agree with Brad, #7 swallows more air as it has whatever airflow is remaining in the intake pushing it through the cylinder. Tuning an individual injector would require aftermarket ECM, a little $ for most nitrous users...we like it cheap and quick. Add to this problem, in the nitrous world a lot of ppl run a wet kit tapping off the rail. This draws more fuel away from the drivers bank, further leaning out the #7 cyl. I would be more prone to say it was majority of "airflow ramming" from being the last cyl. but when you look at a set of plugs that fail from running lean on a wet kit off the rail, #5 will look worse then #8. #8 in that case SHOULD look closer to #7 since its in the rear as well, but the fuel being pulled from Bank 1 leans out all odd cyl. more than the ramming airflow in and of itself. Add them together and your scewed. Quick solution, increase jet size x2 for #7, x1 for #5. #3 & #1 have less trouble since the fuel leaving the rail has to go by them on the way out. Thats my theory and until someone proves me wrong I'll stick to it.

 

NO no not talking about tuning each cylinder seporate just talking about getting a liitle more fuel in the trouble areas if air flow is what is promoting the lean problem. Now I have talked with poeple that have problems with stand alone system also. The tuning to me is IF you just need a little more in one or 2 holes, and you have some injectors that are a couple of pound more just plug them puppies in. Still tune the car the same as before. You are just dumping a little more fuel into one hole. Just like the old mechanic injection or direct port stuff, just add a little. but hey just an idea. Why buy 8 when you could buy 1.
Ricky

 

This makes sense....well sort of...why not ...i'll get back to you...

 

Ricky,
If you call Katech they can tell you what the fuel difference would be, I am sure its pretty consistent if there is any difference.

 

We run 8 widebands on most of the engines we dyno. There are constant variations and we do not see any particular cylinder being a problem.

 

A few people have gotten trash in their #7 injector and posted about it, but I think over-all it is a heat related problem.
I posted a picture of the #7 intake runner in this thread to show how it probably flows less air than the others.
https://ls1tech.com/forums/pcm-diagnostics-tuning/498726-misfire-7-removed-cats-help-please.html

 

At the least you could flow your injectors and put the fattest in #7...

 

Ricky, your talking about one injector, but to find the right size would be extremely difficult, look at the flow differences we're talking about! That is correct for the flow matched highest injector going in the softer hole. I agree heat plays an issue to some extent. I just dont see how #7 could possibly be getting less air though as post interpretation from Whites pic. If there is a 1mm devation in port, and its at the end it still going to see the most air.

Jason @ Katech... Would you agree dynamics on an engine dyno with NA engines and nitrous could be quite different in the flowing of air at speed compared to stationary on dyno? Not doubting what you say, but I cannot agree in a blanket statement, without some kind of evidence, that Bank 1 #5 and 7 cylinders dont have some kind of issues. Guys w/ FI tend to blow #7 often enough, then add in Nitrous guys and seeing #5 and 7 going out there as well, positive correlation can be made that in Power Adders, the #7 cylinder is at the most risk. Combine the heat, airflow and fuel tapping off the rails for nitrous guys and I believe that makes the difference in knocking off chunks of the ring lands. FI guys breaking #7 ringlands as well, and they dont tap off the rails for fuel, could be coincidence that in all those cases #7 has the lowest flowing injectors...I highly doubt, odds of probability are against that. How about FI essentially fills the intake with air more than NA can, and this pressure is more easily lowered by #7 as there would be less turbulance for the air to try and enter into the end cylinder than others, thus adding more air per stroke than others.

Personally I havent heard of anyone having issues with #7 on NA engines.

Back to you.