Weissach Vampire

I have a question for you rennlisters about boost spikes!

I have a GuruRacing TurboS chipkit, an apexi AVC-R and a Tial 38mm wastegate. I use the autoconfigurationmode on the apexi(set to 1.05 bar=15Psi) and it holds boost ok on third gear, but when I floor it on fourth and fifth gear i see up to 1.2 bar boost before the apexi adjust it down to proper levels. I don´t know for how long it overboosts(I´m kinda busy looking at the road under these conditions) but after the runs I check the max aquiered boost on the Apexi.

Is this dangerous or should I just forget about it? Maybe I should use the "start duty" setting on the Apexi and turn down initial dutycycle?

Thank you.

Tom M'Guinn

Lots of people rave about the Apexi. I tried it and could never get it to hold a steady and predictable boost level. I had the same kind of problem you are having. Other people claim there is nothing better, so I dunno. Short of a dyno, where are you supposed to tune the 4th and 5th gear boost maps? THere may have been something wrong with mine, I dunno, but I finally gave up and re-installed the Profec B, which holds boost exactly the same in every gear at whatever lever I spin the **** to.

Weissach Vampire

Ok, thank you Tom!

Anyone else with experiences of the Apexi EBC(good or bad)? Maybe these boostspikes are "by design"? Haven´t noticed any pinging when the boostspikes occur, the car just pulls like crazy(the question is for how long).

sybelix

yup, please more comments about avec-r.
our gruppe951 here in Finland, we are thinking whether to buy those or not

tazman

Do you have the gear specific self learning turned on?

If you have that turned on then you need to adjust the F/B speed in the upper gears.

Theo951

Reduce the "start duty" on the gears you noticed the overboost.
Typicaly should be zero, or even negative figures in a huge turbo with MAF & KN
When done, go to learn mode off in all gears.
Tazman has right mentioned. F/B shloud around 5.
AVC-r is one of the best part installed in my 951.

NZ951

I feckin hate EBC's. A manual one works so much more consistently. I still have my EBC. I get boost spikes when accelerating from 2000rpm in 4th. But not in 1,2, or 3... sucks really.

Weissach Vampire

Yes, I have the gear specific self learning turned on. I will try to set the F/B speed to 5 in the upper gears as suggested, hopefully that will help. Or is it better to turn of selflearningmode?

Weissach Vampire

Oh, by the way, Tazman, I notice that you have almost the same setup as I do, did you have "rock solid boost" from the start when you installed your mods, or did you have to tweak alot to get it stable??

Thank you!

tazman

When I first installed the AVC-R with the stock waste gate I had to do a lot of tweaking to get the most out of it. Then I installed the Tial run in only singe port mode and I had to change things I had set to compensate for the weak factory unit. I should of posted these before but here are some things that were sent to me when I installed mine 1 & 2 Also if you go to OZ951's site he has some information and links to the text documents above.

With my APE chips and even the hacked set of Guru chips, I had a big fat rich portion under 4000rpm and I was running over 1.2Bar of boost and that was awesome. I had to drop the boost to below 1 bar above 5000RPM or else I would be to lean up top. You could not do that with a mbc. I was using a WB O2 sensor but no matter how much I turned up the boost I could not get an acceptable A/F ratio in that lower range.