Go back to previous topic
Forum nameTurbo/Nitrous Tech
Topic subjectturbo question
Topic URLhttps://forums.2gnt.com/dcboard.php?az=show_topic&forum=i8&topic_id=15010
15010, turbo question
Posted by mitseclps, Feb-04-02 01:46 AM
i know the subject was a tad general, but i couldn't explain it in justone line w/o confusing everyone. here goes:

every now and then my car feels like it's bogging down in the middle of driving, almost like it's getting way too much fuel for what i'm doing. it's fine if i'm racing, it'll fly and the a/f reads rich the whole way, but if i'm just driving, lets sat at like 80mph, and i step on the gas and slowly accelerate (or lets say i get up to speed and then accel/decel a few times just screwing around), sometimes it'll lerch like the engine is not sure what the hell is going on...ya know what i mean? any ever experienced? i remember seeing a post a while back about hesitation boost, but i didn't see it in a quick look thru of the archives, maybe i missed it.

any ideas? i won't be too worried if its just getting too much fuel, but i'm just making sure this isn't bad or anything.
15011, RE: turbo question
Posted by phrenzy, Feb-04-02 06:32 AM
I've never really noticed mine doing anything like that, although at certain speed/RPM combinations the boost seems to be less powerful. One thing I have noticed about turbos in general is that it doesn't feel as fast as an equally powerful all motor car. I attribute this to the fact that the power comes on in two stages. Lets say you running in vaccum at 3500RPM, you step on the gas and you first get the motor pull, then a second or so later comes the boost. In an all motor car, it comes on all at once.

OK, I'm just babbling.
15012, Why does your car feel boggy at certain rpm points under boost?
Posted by JasonESi_T, Feb-04-02 07:04 AM
You're right...bogging at certain RPM's just means you're probably getting too much fuel at one particular rpm/ boost point as opposed to another. Why?

Because one should NOT expect a boost dependent FPR to be able to tune your entire rpm curve BY ITSELF within that curve. The FPR should provide a rough exponential graph to how much fuel you need under boost, with strong emphasis on providing enough fuel at your maximum boost/maximum rpm. Everywhere else in the rpm/boost curve gets sacrificed in order to facilitate our low cost desire to supply enough fuel under boost mechanically in an electronically fuel injected car.

What does this all mean? It's totally normal what you're experiencing. You need to alter your fuel system if you want perfect non-boggy acceleration under boost.

I like referencing this page to sum up where your fuel system racks up and what else is available out there and how much you're willing to spend: http://www.ttiracing.com/turbo_tech.htm