When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Thanks Jim, but in this case, I just cranked the screw (bolt) down to increase the FP at idle. Got it up to ~48psi. Took it out for a full pull and it is now pretty much dead nuts on. Still a tad lean at 6k (15.1) but the came down nicely to 14.3 at redline. ...
Dude, an AFR of 15.1 at 6K WOT is not even close to dead nuts. And don't confuse static pressure with flow against pressure, the beast needs to be fed.
Hi, I don't know a lot about everything, but I claim to know little about something.
I believe a lean condition is a symptom of advanced timing.
check the timing, ..
Maybe bad o2 sensor.?.
just a suggestion.
You specifically want the early 87 FPR that has a hose barb.
Thanks Brendan. Will source one.
Originally Posted by jcorenman
Dude, an AFR of 15.1 at 6K WOT is not even close to dead nuts. And don't confuse static pressure with flow against pressure, the beast needs to be fed.
Cheers, Jim
LOL! OK... not dead nuts. Sorry for my lame attempt at Kibortization. I was just happy that the car was no longer sputtering. I'll get the correct FPR and then double check AFRs.
Originally Posted by OTR18WHEELER
Hi, I don't know a lot about everything, but I claim to know little about something.
I believe a lean condition is a symptom of advanced timing.
check the timing, ..
Maybe bad o2 sensor.?.
just a suggestion.
Thanks buddy. Timing was the first thing we checked. It was off a tooth, so then we used the PK32Ver and dialed it in. But now it's pretty clear the FPR is the dark horse in this battle. Will get it swapper out and then be done with it.
Now with your TPS plugged in go run it again. You would not be getting WOT map and the O2 would be in closed loop. The AFR at full throttle should drop, assuming the TPS is working correctly.
Now with your TPS plugged in go run it again. You would not be getting WOT map and the O2 would be in closed loop. The AFR at full throttle should drop, assuming the TPS is working correctly.
Yup... Thought about that too. Working on re-installing the accusump for now. If I have time today I'll take it out for another run.
You would not be getting WOT map and the O2 would be in closed loop. The AFR at full throttle should drop, assuming the TPS is working correctly.
At part throttle the S3.S300s LH chip will go off-loop and is supposed to drop into the 13's over 2000 rpm at high load, or anytime over 4000. 'Sport Mode' is not rich enough to work at WOT if the TPS is bad/disconnected, though.
On the track (dyno too), plugging the single LH harness plugs together will help make sure the fueling stays over-rich to keep things cool during sustained full throttle. On the street it's usually not needed.
I got my Accusump installed today. But I did not have enough time to plug the wideband O2 sensor back in and retest The AFRs.
Originally Posted by PorKen
At part throttle the S3.S300s LH chip will go off-loop and is supposed to drop into the 13's over 2000 rpm at high load, or anytime over 4000. 'Sport Mode' is not rich enough to work at WOT if the TPS is bad/disconnected, though.
On the track (dyno too), plugging the single LH harness plugs together will help make sure the fueling stays over-rich to keep things cool during sustained full throttle. On the street it's usually not needed.
Ken, that's great information. Thank you very much. I have a new 87 FPR already on order. I probably won't be able to install it until next week. At that time I will recheck AFR's with the wideband O2 sensor.
isn't max hp attained having afr of 12.5 at wot ????
Hi Andy,
Yes, mid-12's is generally ideal for WOT at close to redline. After countless hours at the dyno, you want to generally see the AFRs coming down from mid/upper 13's in the 4k-5k range and steadily drop as RPMs increase.
But each car is slightly different (cams, timing, spark plugs, etc.) and one might make slightly better power with a slightly different setup.
Originally Posted by Lizard928
Max HP is 13.1-12.8 AFR on most engines.
If I saw 13.1 though I would be shutting things down and not proceeding any further.
At idle AFR should be cycling to 14.7:1
WOT 12.5 is better to see.
Hi Colin,
Ignorance in bliss. In hindsight though, I should have never run the car in that condition. I need to fabricate a small panel to mount the WB AFR gauge so that there are no more surprises.
I got my Accusump installed today. But I did not have enough time to plug the wideband O2 sensor back in and retest The AFRs.
Ken, that's great information. Thank you very much. I have a new 87 FPR already on order. I probably won't be able to install it until next week. At that time I will recheck AFR's with the wideband O2 sensor.
isn't max hp attained having afr of 12.5 at wot ????
yes, thats when most engines make their best power and are in the safest zone. 14.7 is stoich and thats where bad things will happen. highest egts and CHTs. thats ping-ville. above 16 is pretty safe too, and thats where you run cooler but lose power... and a lot of power as you go leaner and get into rough running-zone.
our cars are pretty easy to tune with a RRFR which works well on the AFM cars.
no excuse to run your car at above 13.5 :1 at the track. its too close to the danger zone and not optimal. stock cars will generally run in this zone with no mods to fuel or timing, but maybe headers or other mild mods.
have you done any video tests to see what that splitter is doing at speeds over 100mph? thats a hell of a lever on the mounting hardware of the plastic air dam. is there support i cant see.... like it is really long under the engine. otherwise, you might want support wires. (ask me how i know. )
BTW, here's a short vid from the last HPDE... Fun times.
you should really get that camera mounted behind you so we can see driver input. Nice laps.. you need to really get the car in the lower gears before the turn in. especially like turn 1. leaving all sorts of time as well as control on the table. If you are doing that to save the motor, dont.... the track hot 928 needs the RPM higher in the turns or the oil flow falls off, and pressure goes down. plus with the RPM higher, you have much more rear end control with the throttle both in slowing and accelerating.
09-07-2015, 03:58 AM
OK... not dead nuts. Sorry for my lame attempt at Kibortization. I was just happy that the car was no longer sputtering. I'll get the correct FPR and then double check AFRs.
In hindsight though, I should have never run the car in that condition. I need to fabricate a small panel to mount the WB AFR gauge so that there are no more surprises.
)