MoTeC Global Forum

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?

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

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

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?

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.
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).]

how did you solve the issue?