Why so Rich???

V

VA VIPERAM

Full Access Member
Joined
Dec 21, 2006
Messages
378
Reaction score
1
Why do our trucks run so rich?
Every dyno sheet I've seen from our members shows the A/F ratio around 10:1.
My truck cruises and idles rich.
Most engines I build run best around 12.8:1, and they're carbureted.
MPFI engines should be leaner.
What gives?
 
These trucks are slightly lean down low and rich mid / high rpm's

Just how they are from the factory (tuned)

12.0-12.5 for N/A wot is good and 11.5-12.0 is good for F/I (conservative)

Get a Flash or a aftermarket piggy-back computer if you want to change the tune...
 
VA VIPERAM said:
Why do our trucks run so rich?
Every dyno sheet I've seen from our members shows the A/F ratio around 10:1.
My truck cruises and idles rich.
Most engines I build run best around 12.8:1, and they're carbureted.
MPFI engines should be leaner.
What gives?
Click to expand...
Yeah...good question!!!
And are the trucks tuned differently?? Say for different parts of the country?(elevetion?)
 
SRT-IZ-4me said:
Yeah...good question!!!
And are the trucks tuned differently?? Say for different parts of the country?(elevetion?)
Click to expand...
no tune is all the same...MAP sensor is for elevation that changes that.
 
RedSrt007 said:
These trucks are slightly lean down low and rich mid / high rpm's

Just how they are from the factory (tuned)

12.0-12.5 for N/A wot is good and 11.5-12.0 is good for F/I (conservative)

Get a Flash or a aftermarket piggy-back computer if you want to change the tune...
Click to expand...
:dito: They are set 'safe' from the factory. They are protecting the motor from any possible conditions the vehicle may see. Corvettes and Mustangs are also very rich.
 
SWIFT said:
12.8-13.1 is ideal for NA , 12.0-12.5 would still be rich
Click to expand...
Still to lean for my liking...maybe on other motors, but not these creampuff internals...

12.5 would be the leanest I would go @ wot on a N/A Gen 3 w/ stock internals

Just my opinion of course :)
 
Stingray said:
I would say only if it's an aggressive tune - too much timing or too lean.
Click to expand...

Would you classifly any of the three options (x metal, DC Perf., B & G ) as aggressive or safe? I know there have been some possible situations with the vec II which may or may not have been the cause for the engine failure. I ask because if I was ever to blow my engine, I would have to have the engine pulled and shipped back to the mainland. It would be a pricey problem. Thanks for your input David.

patrick
 
mauiSRT/10 said:
Would you classifly any of the three options (x metal, DC Perf., B & G ) as aggressive or safe? I know there have been some possible situations with the vec II which may or may not have been the cause for the engine failure. I ask because if I was ever to blow my engine, I would have to have the engine pulled and shipped back to the mainland. It would be a pricey problem. Thanks for your input David.

patrick
Click to expand...


If I was in your situation, I probably would play it safe.....seems like a lot of risks at hand (not that the flash's are not safe), but IF something happened, I would hate for you to deal with the hassle :eek:.


If you really wanted to go aftermarket, a wideband and a good ear (or knock sensor kit)

-Red
 
12.5 for me without NOS
10.8-11.5 with NOS (a little harder for me to control, so I stay safer)
 
RedSrt007 said:
If I was in your situation, I probably would play it safe.....seems like a lot of risks at hand (not that the flash's are not safe), but IF something happened, I would hate for you to deal with the hassle :eek:.


If you really wanted to go aftermarket, a wideband and a good ear (or knock sensor kit)

-Red
Click to expand...


This is why I have not got the flash........ and went with upgrading the gears. I get more seat of the pants speed without messing with the motor. Looking forward to getting my x metal mids on soon too.

patrick
 
mauiSRT/10 said:
Would you classifly any of the three options (x metal, DC Perf., B & G ) as aggressive or safe? I know there have been some possible situations with the vec II which may or may not have been the cause for the engine failure. I ask because if I was ever to blow my engine, I would have to have the engine pulled and shipped back to the mainland. It would be a pricey problem. Thanks for your input David.

patrick
Click to expand...
I have never seen or used their tunes but I feel the stage 2 tune is approching 'aggressive'. I'm just going from reading about some of the guys having detonation after getting those tunes. Like Patrick said, the safest is no tune. If you want one though, stick with stage 1 or have a custom tune done that's conservative. I would also recommend a wideband. After I installed my VEC2 I used a program that Roe said to start with. It was way too lean - 14.0! I had to add a crap load of fuel.
 
mauiSRT/10 said:
This is why I have not got the flash........ and went with upgrading the gears. I get more seat of the pants speed without messing with the motor. Looking forward to getting my x metal mids on soon too.

patrick
Click to expand...
The stage II flash from DC Perf is still PIG rich. My pipes still run VERY black. I have asked them for a leaner tune and they will not do it without custom dyno tuning.

I think their stage II is very safe.
 
The DC tune is rich. When I installed their blower flash I commented to them on the occasional black smoke and dark areas around the exhaust tips. Dan mentioned that they make them more on the rich side to be safe.
 
ViperTruck and DaveT - No offense but you cannot gauge your A/F by the look of the exhaust tips. Only a wideband O2 is going to tell you. You could be pig rich at idle and cruising but not at WOT.

Like I said before I have never used those tunes so I don't know where they run. You could very well be pig rich at WOT, but I like to be cautious and not assume ;)
 
Stingray said:
ViperTruck and DaveT - No offense but you cannot gauge your A/F by the look of the exhaust tips. Only a wideband O2 is going to tell you. You could be pig rich at idle and cruising but not at WOT.

Like I said before I have never used those tunes so I don't know where they run. You could very well be pig rich at WOT, but I like to be cautious and not assume ;)
Click to expand...
Good point. No offense taken. :p
 
Definitely safer to run on the rich side. I have never burnt a piston or had any internal damage to any drag motor I have ever set up for myself because I always set them rich. I know that carbs and EFI are totally different animals, but I set my carbed motors up so they run about 11.5-12:1. It also aids in quicker warmup times as all of my drag cars are also street driven. Two pumps on the pedal, turn the key, engine turns over, gently press pedal for 15 seconds, then let run for a couple of minutes and she is warm enough to be on my way. Set a carbed car up to act that way and you will never fry a piston or break a rod, no matter how much heavy-duty drag racing action it sees!! That's probably the same principal the mopar engineers were thinking of when going so rich in the factory setup. Plus, they probably figure there are gonna be a lot of knuckleheads building up these motors without adjusting the timing and fuel curve, so better safe than sorry. Just my rambling $.02

Greg
 
You must log in or register to reply here.

Latest posts

Support Us

Become A Supporting Member Today!

Click Here For Details

Random Media

IMG 0120 1
image
6985664969 accfa71b60 m
IMG 20120703 074742
Back
Top