new and in need of help

[NEARING]

I've only had my GN less than a month, 5 passes down the track,
I can't seem to get the launch right, it seems to stumble or bog off the line and then just scream!
Could the 84's be too big? Car idles fine in gear.
Only seems to do this at the strip,will melt the every day tires from a 45 mph punch on 18ps& pump gas with a splash of octane booster. Should I not be going to the wood off the line?
Times in sig.
Thanks for any help,I need it!

 

[NEARING]

Any ideas or is this just a dumb question. This is my first turbo anything so I am kinda in the dark.
thanks.

 

[KEVINS]

My GUESS would be that it is the Speedpro programming possibly due to the large injectors but a programmer would know more about this than me.
Are you launching it off the t-brake? Is it loading up? Do you have any scan files for someone to look at?

IMO, those are BIG injectors...

ks

 

[NEARING]

thanks for the reply.
no it isn't loading up the boost just seems to drop off to nothing and then comes to life. like a 850 holley on a mild 350.
yes I was trying on the T-bake about 8-10psi.
I am having a hard time getting my windows xp to work with the
FAST but Bobby Mason was looking at it with his lap top the first night I had the car at the track and didn't see any thing obvious.
I guess I'll just have to keep at it.

 

[GS70350]

does the car have the stumble when driving around too? Because the problem may be that your cam sensor is not adjusted right. i had a bad stumble like that, the car would practically just die for about half a second then would instantaniously jump back, you give it gas, it drops off then comes back up just like you seem to describe, then it screams like it should. turns out my cam sensor was set wrong, i adjusted it yesterday, now the thing has no stumble like that, and cant believe how fun this thing is to drive now!!! guess i never noticed how annoying it was before.

 

[GS70350]

Oh, and 1 more thing you could think about, is that when i switched over to the 50lbs injectors from stock size ones, the stumble was magnified, it was worse than before. so your big injectors may be making a slightly maladjusted cam sensor cause a bigger than normal problem.

 

[NEARING]

No only does it at the track,no problem around town.
This weekend I will try to leave on the converter only.
thanks.

 

[ChrisCairns]

Originally posted by NEARING
I've only had my GN less than a month, 5 passes down the track,
I can't seem to get the launch right, it seems to stumble or bog off the line and then just scream!
Could the 84's be too big? Car idles fine in gear.
Only seems to do this at the strip,will melt the every day tires from a 45 mph punch on 18ps& pump gas with a splash of octane booster. Should I not be going to the wood off the line?
Times in sig.
Thanks for any help,I need it!

Nice looking build....that's a 10 second recipe with more boost.

Anyway, the nice thing about the FelPro is that you CAN run large injectors with no problem so I don't think the size is your problem.

First, don't use octane booster. If you're talking about that 104 crap it's just extremely expensive and fouls the plugs and the O2 sensor. Plus it doesn't add 7 points of octane....it adds .7 points. Use a couple of gallons of toluene or racing fuel to up the octane....although if you're racing you should use pure race fuel.

As Lawrence Conley once said...."If you're not ready to race, don't."

Second, what is your A/F ratio set at around the rpm where you're bogging? I'll bet it's too lean. Once you release your brake you put much more load on the engine and need more fuel at that point. I idle at around 12.5 to 1 and at around 3500 I have the ratio at 11.9...then gradually lower it to 10.9 to 1 at 5000 and above. Keep in mind that's in my stage car though. I also have another car with FelPro and I found my best ratio was higher (leaner) than I just quoted so you are going to have to experiment. But that's somewhere to start.