Hi,

I followed the threads according the leaning out problems for months, so I wanted to make my own picture of this topic and wanted to find out what my car is doing while driving on the street.

O.K., with the help of my tuner we have found out it runs perfectly on the road, just the way we wanted.

We installed an extreme accurate wideband from my tuner (exhaust temperature corrected!) right after the engine with no cats in between! (I have no first Catalytic converter). We also watched the Knock Detection on each Cylinder with Star Diag in real time while we were driving on the road up to approx. 180 MPH on the Autobahn. After the first run we richened the mixture a little bit to a healthy 11,9 A/F, to even further minimize knock activity. Now only on one Cylinder there is insignificant knock activity at redline.
On another test ride I measured my fuel pressure while driving up to approx. 180 MPH on the street in 5th gear. No fluttering of the pressure, as we expected with the SL55Fuel Pump. Pressure is right in the specs.

My conclusion:

I will only speak for my car, every car is different. Different boost, different IATs, different intake. Even different boost-level when you start tuning...My car is NOT running lean with the SL55 Pump (which I installed 2 years ago),the regular fuel pressure regulator, and the correct tune for the car. It runs perfect even during real High-Speed runs. My boost-pressure is 19-19,5 PSI and IATs never go above 130 degrees F. This helps the car a lot...

Attached you find two pictures. Preparing the car for test drive on the road with Lambda-AFR-Meter and Star Diag. And Fuel pressure testing while driving on the way to the Autobahn...

 

what are the mods your running? i recently installed the dashdaq system in my car and readings are 14.7 afr at idle and 12.5 afr at 140mph steady thruought the acceleration range. my mods are conservative with only the c3 pulley intakes and dyno tune with no changes to the fuel system. i run 55 psi fuel pressure with max boost at 18 psi. iat's run @ 95* F AT 80*f outside temps.
i can datalog a run to max if anyone wants it

 

Thanks for taking the time and using great tools to datalog and share your information.

My car was tuned while being monitored with the star diagnostic system and they looked at all the engine parameters - taking pretty much a full day to dial it in.

I never run lean with the stock fuel pump - but then again - mine wasn't monitored "on-the-road" at sustained high speed. Nothing like true road data. Thanks for the 411 on the SL55 fuel pump; proven mod, eaisly installed, no adjustments.

The AMG SL55 comes through again for it's little brother...

BTW - had to be great fun dataloging at 180MPH!!!

 

That data also supports 'bulldoggers'(?) results with the SL55 pump.......

 

I'd like to see a run to 150+, to compare with my IAT's at that temp (hit 170*F at ~150mph = 5900 rpm as measured by PLX / Rev, with -9.0 degrees of timing)

 

bill ill try to get that info today if i can. high speed runs arent easy around here, to many cops!!!

 

Thanks.

Yes it was great fun, although a little bit windy with the window open because of all the wires and the hose
According to the SL55 Pump I can only speak for my personal car with my tune and that it works with boost around 19 PSI.
Would be great to see you again doing the texas mile with your car and taking the time you need for it

@32krazy
I have only the common mods which are used here, maybe one or two little secrets... But nothing special.

 

You should tell us the little secrets! great info!

 

If at WOT, you’re a/f starts around 11.8 and at redline prior to shifting, it ends around 12.8. That is a lean condition, it definitely is not detrimental but it is a leaning issue. It’s an indication our fuel system is not able to keep up with fuel requirements. Why? The reason leaning occurs in the higher rpms is because that’s when you create max boost. The closer to 20psi you get the leaner you will go.

In 4th gear, I reach 20+ psi in cooler weather and I have experienced extreme leaning at max boost with the SL55 pump. In 3rd gear I can reach 19ish psi and my a/f mimic those in the first paragraph with the SL55 pump, which is an acceptable lean condition, I presume. In 3rd gear with the OEM fuel pump, a/f would reflect 12.3 to start and end at 13.3, same boost level but the OEM pump flows less at boost levels less than 20psi. Once you reach 20+ psi it doesn’t matter what fuel pump you are running, your leaning condition will no longer be acceptable, IMO.

Prior to LET creating the 181 and 185 pulleys, the largest pulley available was 178. IMO, the reason for this was because the 178 pulley was capable of producing the maximum amount of boost without having adverse affects on the factory fuel system and other variability’s.

SLK32Germany is correct the SL55 pump works around 19psi but not at 20+. Thanks for sharing SLK32Germany!

 

I've not seen an ASP 178mm pulley - but from what I've seen on the ASP website and what I've read on the forum; the 178 is only a "press-on" outer belt ring using the OEM hub. This would help eliminate alignment issues due to manufacturing tolerance problems. Plus - I bet you can access all the water pump bolts without removing the pulley. With the two piece 185MM design - you have to remove the outer hub when you remove the water pump. Not sure of the 181mm.

I'm guessing that's the main reason behind the ASP design - that and to ensure the OEM belt fits. (a big marketing strategy) Not over-boost issues if it only comes down to 1 PSI.

Regardless of what pulley you install - would you have lean issues if you didn't raise the RPM rev limiter when you tune?

Could you compensate for these lean issues with proper tuning techniques if you do raise the rev limiter? Is that something that's easy to do with a "mail-in" tune?

True data-logging at 180MPH can't be over looked

Just some random thoughts rolling around.....

 

Sure, there could be multiple marketing reasons for the designing of 178 pulleys. It’s not farfetched that part of the design also takes into account certain limitations of our setup, if there was no acceptable solution to overcome those limitations. The 1 psi is the difference between 12.8 a/f in 3rd and 14.0 a/f in 4th and 17.xx a/f at 21 psi in 4th as well.

You would have a leaning issue regardless of the pulley you run because of increased boost over stock. The problem is when you reach 20+ psi, for me in 4th gear in cooler weather is when the lean issue becomes unacceptable or detrimental to the engine. I think you would still have a lean issue if the rev limiter was not raised because max boost is obtained around 5300-5500 rpm. Maybe reducing the rev limiter via tune could work ; if it could be raised I don’t see why it could not be reduced. How much more power do we make from having the rev limiter raised over factory setting?

::Edit::
Not over looking high speed datalogging/ Tuning, but 20+ psi was not reached.

 

srt6 gangmember i thought 11.8 to 12.5 was ideal for afr's? isnt 11 in the rich range and 13+ lean? im asking becuse im new to the datalogging and trying to grasp all the info.
if he sarts at 11.8 and ends at 12.5 its going to lean side but still in the acceptable range isnt he?

 

I don't know what an ideal afr should be, though i would suspect it should be a straight line, i.e. 12.0 +/- .2 through redline. Not starting at 11.8 and gradually leaning out on the top end @ 12.8. You are correct 11's are on the rich end and 13's are on the lean end. The lower your number the richer you are, the higher your number the leaner you are.

Yes, starting at 11.8 and and ending at 12.8 is acceptable, I presume. The gradual increase in afr is a leaning condition, you are not running lean, but your ending afr is noticeably leaner than what you started out at. I think all of use have this (acceptable) leaning condition and I don't think its by choice. Its a product of our fuel system and elevated boost levels.

 

i sort of see waht your saying. mine for example at idle is 14.7 which is atmospheric. then stand on the throttle and it dives to 12.5 and stays there thru 140 mph top gear. from what i understand this is a very good example of a proper tune

 

Yes, all of our afr should be trying to maintain 14.5 +/- .3 at idle. At WOT, an afr of 12.5 all the way through redline tells me the tuner can actually control your fuel curve and your fuel system is adequate .

::EDIT::
A good barometer would be a SRT6/SLK32 that only has a tune. It would be interesting to see their afr, since they would still be pushing stock boost levels.

 

thanx. i put my trust in tony at e/c and i now know he did just what i wanted. the threads on mbworld had me concerned not so much over his tuning but over my inability to know what was going on inside the engine. thanx to 240m3srt and rcompart i know have all the info to race with confidence!

 

No problem. Tony tuned my car as well and I have nothing bad to say nor any concerns. Tuners can only do so much before our cars start limiting them .

 

Srt-6 Gang member is exactly right as soon as our cars start hitting 20 plus pounds of boost they want to lean out bad. When I had my dyno tune done by Ton with stock fp and fpr. After 1.5 hours the best he could do at the top of third was mid 14's afr. Now that I have a walbro fuel pump and AEM fpr that has a 1-1 increase for boost I am able to hold AFR's into the 11's if I want. It takes a increase in fuel pressure from the stock 60 psi up to between 72 to76 psi. There is a fix for this it just takes time patience and money to make it work. Talk to Rob at NW for more details.

 

Not mine - and I can hit 20 PSI any time I want... with the stock fuel pump.... Go Figure..

https://www.crossfireforum.org/forum...tml#post485465

 

You, MikeR and Bulldogger are the three X factors I think of when trying to figure out this 20+ lean issue. I'm able to watch boost, RPM and A/F all at once under WOT on street or Track. At this point you three can not, please correct me if I'm wrong BB, MikeR or Bulldogger. If you can't monitor those items or a/f at the least, how can you be sure leaning is not occuring?

Please don't take my post the wrong way, I'm simply trying to find the answer to a problem. Eventually, we will figure this out!