Adding Boost

[Stainless Steve]

I'm currently running 10 psi with a boost controller and MBE ecu and MAP sensor, my tuner says I should ideally get it back on the rollers to up the boost to 14 psi.
My question is, should the MAP sensor really be trusted to do all the correcting on the fueling? Bearing in mind I have a wideband AFR gauge for reference.
I know in an ideal world it would be great to get it checked on the dyno, but in an ideal world I would be a millionair! ???

 

[wahly68]

Dyno is cheaper than a rebuild!!

 

[PaulCav]

There is noway I would think of running the boost up without having it tuned on a dyno. It only took me 3 passes (25 seconds.) on the track in Bristol to melt my pistons when the FMU came off line.

The dyno is way less expensive.

 

[Stainless Steve]

I hear what you're saying, but surely the whole idea of MAP based mapping is for the system to compensate according to boost.
I'm not saying I won't get back on the dyno for reference but theoretically I shouldn't need to.

 

[ogre]

the map sensor is just that. a sensor. it senses the pressure in the manifold and sends that information to the ECU. your ECU is what makes adjustments for more boost. your map or "tune" is what ultimately determines if and how much fuel is added at a given boost. if you're running ecueditor, you may have a GM 3 bar map, but if you're running the stock map sensor, it's entirely possible the sucker is almost pegged at 10 psi. this sounds like a smithabusa question, and based on your post, i'm going to guess that you don't do your own tuning, and may not understand the finer points of engine management. bearing this in mind, i would definitely recommend going to your tuner and having the bike remapped for the amount of boost that you wish to run. best of luck, and i hope you take a vid on the dyno, we're all envious of the turbo busas.

 

[Stainless Steve]

Sorry Ogre I may not have been clear enough, I have a fully programmable MBE standalone system with 3 bar MAP sensor. I have had the motor mapped to 10psi and just want to add some more boost.
The motor is in a car weighing 1100lbs by the way.
[video=youtube_share;vrkM8cDJzwY]http://youtu.be/vrkM8cDJzwY[/video]

 

[ogre]

what's that i taste? is that... my own foot? fair enough bro, if you have the software, go ahead and map it yourself. does your wideband datalog? or have a 0-5v output to run into a datalogger, along with a tach signal and tps? what parameters are you logging?

 

[Stainless Steve]

Yes my wideband has a 5v output, I'm learning as I go so this forum is the place to be.
I use software called Easimap 6, its free to use with the MBE. If you're interested in that sort of thing have a look. Best way is through the supplier called SBD Motorsport.

 

[POWERHOUSE]

Sorry Ogre I may not have been clear enough, I have a fully programmable MBE standalone system with 3 bar MAP sensor. I have had the motor mapped to 10psi and just want to add some more boost

Whether or not what you want to do is safe depends on the original map in your MBE. You may very well be able to turn it up with no issues; then again, you may lean it out and roast your motor. Keep in mind that you are trying to rely on a boost-reference map in an area that was not previously properly checked and/or adjusted. With all that you have invested, it would be wise to get it on a dyno, where you could at least check what is going on, and possibly dial it in even better, if need be. If you want to be competitive, that is what you should do IMHO. I'm not sure how you can race that car any other way with confidence.

 

[ogre]

yea, when we'd tune our cars (srt4), they were speed density (no maf sensor) as well. we'd log knock retard, timing, tps, map, rpm, injector duty cycle, afr, and egt's. with all that nonsense, you can get a pretty good tune, even without a dyno. when you turn up the boost, turn up the fuel, then add timing, a degree or two at a time, until the power doesn't go up anymore. at that point, pull it back to your last best pull and log your afr. make sure you're not knocking and you should be good to go. it takes awhile to get a good tune through the whole rev range, but the time is well worth it. then you can go on to tune part throttle characteristics as well.

 

[Stainless Steve]

I've only got one more meeting before the end of season so based on that I'll wait till I've done that and get it on the dyno again. It will probably be raining in England next week anyway and the back end is a little skittish in the wet!
Thanks for everyones input.
Steve.