AFR and Boost question

apple

I've installed a BEGI-S and MSPnP. I've driven the car and tuned via datalogs for the last week. Since I've got the basis of a decent tune I've been turning up the wick lately. The kit is not intercooled.
My question is this. I've noticed via datalogs that I'm getting boost in the 6.5-7lbs region at some heavy throttle times. The car is not intercooled. I'm using the base spark map. This sounds like a recipe for destruction. It may be. I can dial it back. But after viewing my datalogs I've noticed my AFR's are around 12 to 13 while boost is going that high. Also, my injector duty cycles are showing the injectors are not maxed out. They reach a peak of 82% at 7lbs of boost.
Common knowledge says that I shouldn't boost this high without an intercooler. The motor is not knocking at those boost levels. The AFR's are good. My injectors aren't maxed. Since all those signs are good am I doing damage by boosting this high?
Thanks for the help fellas.

just because you can't hear any knock does not mean their is'nt any. and if you don't have a way to monitor your EGT's i would not run it over about 12.0 a/f ratio @Wot.drop boost pressure to 5.5-6.0 amp; run a very conservative spark map.at least until you can get it dyno tuned.if you want it to last.

Google quot;detonation cansquot;. It's basically a set of construction earmuffs with holes drilled, and vinyl tube stuck into them and then run to the motor like a stethoscope. You will be blown away by the things you hear. I thought my knock sensor was dialed in perfectly, and then I built a set of those and heard knock my sensor would never have picked up.

Thanks for the advice fellas.
I was thinking about it on the way in and decided over night to lower the boost pressure until I get an intercooler and larger injectors. Better safe than sorry.
Thanks for the input.


Originally Posted by Savington
Google quot;detonation cansquot;. It's basically a set of construction earmuffs with holes drilled, and vinyl tube stuck into them and then run to the motor like a stethoscope. You will be blown away by the things you hear. I thought my knock sensor was dialed in perfectly, and then I built a set of those and heard knock my sensor would never have picked up.

+1
I would not go fatter than 12.0:1 on a street car.  I would have 10-years ago, but now that we get 10% ethanol you have to drop it unless you have incredibly sophisticated equipment, and consistent fuel quality which is highly unlikely.  
Seriously, det cans.
and search. I have a thread there about it and there are some others.


Originally Posted by black jesus
+1
I would not go fatter than 12.0:1 on a street car.  I would have 10-years ago, but now that we get 10% ethanol you have to drop it unless you have incredibly sophisticated equipment, and consistent fuel quality which is highly unlikely.  
Seriously, det cans.

I've seen a corelation between rich engines engines making lots of power reliably, as well as a correltation of lean engines making lots of power spitting rods out. Don't be dumb.


Originally Posted by patsmx5
I've seen a corelation between rich engines engines making lots of power reliably, as well as a correltation of lean engines making lots of power spitting rods out. Don't be dumb.

EDIT:  I meant quot;leanerquot;,not fatter.  I preach the 11.5:1 logic, and made mega-torque because of it.
I would not go leaner than 12.0:1.  Sorry.

I recently boosted to 8psi (peaking at 9.2psi) without an IC. OK, I have a Link ecu with a knock sensor and 550cc injectors, but boosting at that level without being able to monitor intake temps is very risky. Without an IC, for an example, I would see a jump of over 20C just by going into boost - I would then have to let the turbo cool before boosting again.
Best advice would be to IC your set up, find a way to monitor intake temps in real time or reduce boost.


Originally Posted by black jesus
EDIT:  I meant quot;leanerquot;,not fatter.  I preach the 11.5:1 logic, and made mega-torque because of it.
I would not go leaner than 12.0:1.  Sorry.

Good. Don't wanna mislead the children with more appropriately sized turbines to detonation.

i agree 11.5-12.0 a/f ratio is good,better to run slightly richer amp; keep the rods inside of the engine(instead of sticking out of a whole in the side of the block).

also, at 82% duty, you're getting close to 100% quot;realquot; duty and the over-heat zone.  Either up the fuel pressure or get bigger injectors.


Originally Posted by Savington
Google quot;detonation cansquot;. It's basically a set of construction earmuffs with holes drilled, and vinyl tube stuck into them and then run to the motor like a stethoscope.

Here's a photo of Black Jesus's detonation cans, and Larry making fun of them.

Stephanie

Thanks for the tips guys. IC is on the way. I'm sourcing larger injectors. In the meantime I'm busting off the circ-clip holding the wastegate arm on and dialing back the boost.
btw - verified my AFR targets. They start at 13.5 at 100kpa. Then read like so 100 @ 13.5, 150 @ 12.0, 200 @ 11.5 and 250 @ 11.5.
Larry looks like he's wearing a foam dome
.