drintegra

Like the title says just wondering what is a good boosted AFR and overall timming. I am asking as I want to tune with Crome and want to find out the norms and where people make their power. I have read that AFR in the 12's is good under 10 psi. Above that I guess you would want to go richer. Also the timming. I read that overall timming should be good at like 22-26 for under ten and about 20 and below above that. Just want to some people with experience running boosted cars and the tunning set ups they have. Thanks.

raene

You can't "tune" by guessing a timing value, you need to know if it's detonating or not. Look into "det cans".

Your fuel values are pretty much what I shoot for... I go a little richer than that, though. Want more power? Turn up the boost

drintegra

I agree with both statements, but usually there is a timming value one shoots for as a baseline. I read several things emphasizing the need to not run stock timming when boosted due to the increased cylinder pressures. I am not looking for something definitive on the timming side but a ball park. As for the fuel, where do you tune for. I was thinking about 11.5 would be safe, lower I guess with the increase of boost.

jtracing919

AFR in boost around 12.5- 11.5. little richer in higher boost levels. timing is a whole other story. it varies from engine to engine and your setup has alot to do with it. manifold design, icooler size, comp. ratio of engine. etc.
check out pgmfi.org for some basic info on tuning.

raene

I would agree, you'd think there's a baseline, something to start off with, but get the timing tuning gear sorted out before you even try boosting on it. I just tuned a car that would detonate at more than 15 degrees total timing at just 10 lbs - an LS, relatively low compression - but it could happily take 20 degs at 7 lbs. Make sure you can hear the detonation first before you try and tune it!

drintegra

thanks, I understand the need to retard the timming after u hear detonation just looking for some baselines.

jtracing919

I am fairly new to tuning, but from what I've read, 1.25 degrees per lbs of boost on anything over 10:1 and 1.0 degree per lb of boost on lower compression engines is a general starting point. Tuning for MBT on a dyno is the only way to be exact on ignition timing, but I am using 1.0 retard per lbs of boost in steps with my final timing between 17 and 18 at 11 psi between 6 and 8k rpms on my 9.5:1 gsr and I haven't run into any detonation problems yet. but this may differ for your setup?

drintegra

thanks, I am just trying to identify tunning trends as starting points. I will not just tune my vehicle with out AFR and understanding the basics about detonation. My friends car currently has 11.2 afr to 10.8 afr at 7psi and 16.5 total degrees timming in a b20 turbo. Just wanted to compare other set ups and tunes.

jtracing919

search on evans-tuning.com forum and there are a few good topics on tuning ignition timing

raene

My B16: Uberdata (needle sorta shuddered), 12:1 afr on C16 at 12 lbs boost (maxed out the injectors), 18 degs total advance at peak

On 94 octane: 18 degs total advance at peak at 9 lbs boost, 11.2:1 afr (Uberdata).

LS engine: 15 degs total advance at peak at 12 lbs boost on a GT28R, 94 octane, 11.5:1 afr... had probs with the BC, meant to go to 10 lbs only, was overboosting... (Crome)

SC JDM GSR engine @ 10 lbs: 9 degs total advance, 11.0:1 afr... stopped tuning this one at this point, car had too many probs to continue (Uberdata)

People are saying that 18 degs on Crome is different than 18 degs on Uberdata... so be careful! Sounds like you know what you're doing so I don't mind posting up some details

drintegra

Thanks appreciate the information. Timming should be the same I guess it all depends if the tuner is calibrating timming at the dizzy to the initial timming on the EMS(Crome or Uberdata) since timming varies through RPM, the Tunning is totally dependent on having the correct timming at the dizzy intially prior to begining. Thanks again

raene

That's what you'd expect, yes, but the reality of timing is different Hence the stress on det cans

blackeg

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by drintegra &raquo;</TD></TR><TR><TD CLASS="quote">thanks, I am just trying to identify tunning trends as starting points. I will not just tune my vehicle with out AFR and understanding the basics about detonation. My friends car currently has 11.2 afr to 10.8 afr at 7psi and 16.5 total degrees timming in a b20 turbo. Just wanted to compare other set ups and tunes. </TD></TR></TABLE>

i think your friend is a little too conservative in the tune.

im sure he can go to a lil under 12:1 but get that total timing up to around 20ish degrees at 7psi.

my old ls ran a/f in the high 11's, maybe low 12's and total timing of about 20* at 10-11psi on a 57 trim t3/t4. motor had 215k or so on it and it never blew up.

generally, i go for 11.5:1 and about .75 degrees/psi timing retarded, adding a lil in low psi and taking some timing away at max tq. sometimes ill add a degree or so back in up top, to help keep the tq curve flat and carried out in the rpms a lil more

nfn15037

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by drintegra &raquo;</TD></TR><TR><TD CLASS="quote">Timming should be the same I guess it all depends if the tuner is calibrating timming at the dizzy to the initial timming on the EMS(Crome or Uberdata) since timming varies through RPM, the Tunning is totally dependent on having the correct timming at the dizzy intially prior to begining. Thanks again </TD></TR></TABLE>

It's "TUNING" and "TIMING". The actual timing number (between UD or Crome) shouldn't matter if you are tuning properly, so it is really a moot point.

iBrandon

Be sure ur timing is sync at 16 degrees...also it is better to be way conservetive on timing then to be knocking...To save money on dyno time....street tune your a/f with conservative timing...and when you get ur a/f pretty much where you want it....head over to the dyno and do your timing for mbt...most likely if you are running pump...you will hit detonation before you can reach mbt if your pushing high psi....then if you want, throw in race gas and make a second map...you can reach mbt alot easier before detonating and push more boost...

Also it wouldnt hurt to invest a turbo XS knocklite....its a simple system that detects knocking, and it has various levels of sensitivity. It sets your rpm in 3 different areas and follows the curve for knocking, helps elminate the excess of noise or false knock....Plus it has a shift lite along with it....im getting one soon, just an extra precuation...

You can never be too cautious!





Modified by iBrandon at 10:51 PM 5/1/2006

drintegra