EvoPower81

iTrader: (14)

To all the tuners out there and guys that play with their own cars, what do you find makes more power Richer AFRs with More Timing or Leaner AFRs with less Timing? Gues it might be based on the individual car but I would like to know what generally works better

VGergo

iTrader: (3)

safe but not rich afr + the right timing . What is safe depend on the fuel and boost, but timing makes the more power.

EvoPower81

iTrader: (14)

So I guess the best way to tune is start with a conservative timing map with afrs conservative (10.5-11.0) then keep adding timing till no more power is made. After this you lean out the afrs? This way would suggest that fuel has less of an effect going from maybe 10.5 to 11.5 compared to adding degrees of timing? Am I correct in saying this

JohnBradley

iTrader: (30)

11.0-12.0 is 6whp for a given boost and timing level. 12.0-12.5 is 0whp and 10.9 and down can kill up to 20whp.

Boost (airflow in cfm is whats important, not actual pressure so much) makes more power than timing up to a point. The limit that most people are going to find that boost stops making power and timing HAS to be added back in is pretty high up there though so I doubt its a normal consideration.

To add the exact data (its been included in other posts of mine on the subject), I found that from 28psi to 32psi I made 0whp extra when I had the timing at 11* at peak power on my car with the 2.0L. I dropped the boost back down and added 1* and picked up 10whp per degree until I encountered knock again on the dyno. This was 29psi and 13* at peak power with the 3586. On the street I could I run more boost on pumpgas without knock (up to 32psi) but I dont know that it was necessarily making more power based on what I had seen before. For whatever reason it would not do it on the dyno unless I through a splash of racegas in though. It would run 13* and 32psi on the dyno just fine then (just like it did on the street), but I couldnt claim the number as a pumpgas number obviously. For the record it made 606whp.

aaron

deeman101

iTrader: (34)

I was always under the impression that one targets a given AFR, and adds boost and timing (juggling between the two to make the most power) with as little knock as possible. I'm a very noob tuner though...

nightwalker

On 91 octane, I experienced higher trap speeds and faster quarter mile times boosting 26 psi on the stock turbo with a more conservative timing strategy, than boosting 23 psi and bumping up the timing.

It takes testing and tuning, but I usually go for more boost.

Boostfiend

iTrader: (3)

Are you on the stock motor?

RazorLab

iTrader: (8)

From a ton of testing I did on my personal Evo 8 a couple years ago on boost vs timing, 91 octane hates timing but "is fine" with more boost.

With the proper supporting mods I saw much more real-world power from boost then timing on my personal Evo 8. Before I ended up moving to E85 for good, I was running approx 28-29psi on 91 oct, even with a small OG FPgreen.

YMMV

06Black

what i've learned on the boosted cars ive tuned is that i'll sacrifice advance for boost as you'll normally always gain power with more boost. however, this only holds true untill i have to pull enough advance out that the EGT's start to get a little out of control(that limit is dependent on octane IMO)

theoretically, you'll always gain power with more boost, as the higher pressure will cause an increase in flow. but that gain might only by .1hp/psi. the same idea holds true for advance though. but its only good to the MBT mark, past that and your just beating the rotating assembly.

to the guys at English. when you stopped gaining power with boost, did you see an issues with misfires or spark blow out? I'm curious if you would have befitted from a higher dwell setting.

heres a question, on a stock motor what is MBT? if my VE numbers are correct, i'm gonna guess 22-23deg. any one have an answer?

RazorLab

iTrader: (8)

On the Evo 7-8 4G63 that is pretty close.

Evo 9 little lower.

06Black

say a degree less, or three?

also, that makes me more curious. the 9's had a more aggressive stock cam and VVT. so as long as the MiVec settings are the cause, these would both help optimize your DCR at speed. so you should be able to use advance even more effectively(this is all assuming your not seeing KR of course) so the MBT should rise.

hrmmmm.....i wonder what the cause of the lesser efficiency is.
maybe you know? what am i over looking?

JohnBradley

iTrader: (30)

06Black

Evo IX18-19*, Evo 8 seems to be 21 in the best case I have seen. I have seen some variance which I can only attribute to VE difference (factory head casting plays the largest role). For the most part 18* seems to be the magic number even on some ported heads (combo dependent of course). I havent really tried pushing the timing on my car well past 18* to see what it would do, but at 19* it picked up 2hp so I assumed when i did the test I was there.

I ran into spark blowout when the VE was worse. The order went something like this-

stock intake manifold, FP Beehives, S2s, SD, Stock everything actually, ETS 3586 kit with 4" intercooler and 3.5" exhaust-

531 at 29psi at 10* timing. More boost would blow spark out because of how low the timing was, more timing would knock.

Switched to a Magnus and then all the sudden the increase in VE allowed me to push it far further on straight 92. We didnt have dwell control then, do now, so I hadnt tried it to see if it fixed the issues. I did have a Sparktech Non CDI on the car which helped some prior to the Magnus, but dwell still would have made a difference.

Now that we have dwell control I can really push the stock coils further and the aftermarket ignitions even further still.

aaron

RazorLab

iTrader: (8)

To Aarons points, the 05 head castings seem to be much better then 03-04. So that can affect MBT.

06 MBT I see pretty much the same as what Aaron posted.

JohnBradley

iTrader: (30)

Clean run, no knock, plugs at 0.018", 92 octane, 29psi, possibly a light misfire or knock around 7200



Old plugs, everything else the same, the midsfire was attempting 30psi at 10* timing



Overlay of the adding boost, no power gain without timing. I had remembered more boost between each pull (1psi vs 0.5psi) but either my memory or my MAP sensor are funny. The Magnus cast intake manifold was the only change in these runs vs the previous ones posted.

06Black

Guys this is all spectacular info!

are the head castings the same between the 05 non-Mivec cars and 06's with MiVec?(in regards to port shape, runner length, and combustion chamber?

are the stock head flow numbers posted any ware?
whats the OE combustion chamber size?

if the castings are the same, i'll remain confused/questioning why MBT is lower on the MiVec engine. the more aggressive cam should give greater cylinder fill with less charge contamination and the MiVec should allow for an even higher DCR. unless its settings are the culprit here....

hmmmm......

just for the record, i'm not in any way questioning your data. i'm just curious as to why.

thanks again!!