Injector angle.

Forum for general discussions on engine tuning, not specific to a particular motec ECU

Injector angle.

Postby lawnmower on Sun Jul 08, 2012 7:36 am

I am struggling with my methanol drag race motor. I have good horsepower in 1st and 2nd with the lambda showing a little on the rich side at 0.700-0.710. When I punch 3 rd gear the motor leans out and torched the head. The lambda actually goes rich (0.67) and there is no change to the EGT's but the plugs have melted and as mentioned one cylinder torched.

I have 2 1680cc injectors in each runner and they point at each other so are 90 degrees to the port wall,they fire togeather.

Will this cause the motor to leanout like this?
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Re: Injector angle.

Postby Sean on Tue Jul 10, 2012 12:29 am

So the 2 injectors spray at each other? What lambda sensor? What is the egt?
Is it detonation causing your destruction, rather than a leaning out situation?
.7 lambda isn't just a little rich ;)
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Re: Injector angle.

Postby lawnmower on Sun Jul 15, 2012 9:05 pm

Yes the injectors fire at each other,lambda is Bosch 4.9, egt's are 1100-1200F, detonation can usually be felt and probably cause other damage like broken plug ceramic or sqaushed small end bushes? so I think by feel it is just leaning out. 0.7 lambda IS only a little rich, I mentioned in my first post that I run methanol :)
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Re: Injector angle.

Postby Sean on Mon Jul 16, 2012 10:48 pm

I did see you run methanol, but lambda is lambda, it does not change fuel to fuel, afaik. I would call .7 very rich, and .67 extremely rich. I'm not sure what the 4.9 reads to, .67 is the richest an NTK sensor can read.

How much ignition timing do you have? EGT's sound ok, depending on where your sensor is. I'm guessing turbo by the injectors?
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Re: Injector angle.

Postby Holmz on Wed Jul 18, 2012 10:13 pm

Sean wrote:I did see you run methanol, but lambda is lambda, it does not change fuel to fuel, afaik. I would call .7 very rich, and .67 extremely rich. I'm not sure what the 4.9 reads to, .67 is the richest an NTK sensor can read.

How much ignition timing do you have? EGT's sound ok, depending on where your sensor is. I'm guessing turbo by the injectors?


Yeah - I am guessing S/C as it is a drag motor, and the lag from a turbo is most a decent 1/4 mile time. :mrgreen:
I know methanol has a fatter band for rich/lean, but it does not sounds like fueling that is the problem at lambda=0.7

If your EGT is not going up, then it could be knock.
Are both heads wiped, or just one?
the whole head or just part?
The bearings squashed?

The other questions are:
Where is the lambda sensor(S)?
How many EGTs (and how many cylinders)?
Do you know if all of your injectors are flowing?
[I could picture a case where one stops and that cylinder goes to lambda=1.3 (from 0.65)... But then your gross lambda should also go up a touch (I think a 16/15 ratio).]
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Re: Injector angle.

Postby galanos on Tue Nov 19, 2013 6:45 am

how did you solve the issue?
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