Hi,

I went for a road test today and recorded my rpm and afr with the following results (during acceleration)

RPM AFR
1000 15
1500 14.5
2500 11
3000 11
3500 10
4000 10
4500 10
5000 11

During deceleration I am between 14-16 afr from 3000 to 1000 rpm

My engine 5.0 tpi, Paxton sc, full exhaust (headers and catback), water/meth injection, tune up everything else stock.

I was planning on switching to 30# injectors and new prom from tuned performance. The injectors and prom are sitting in my basement waiting to be installed

Do I need to make the switch?

 

Id say "Switch" out the LB9 and the ball driven snail blower.

 

looks like your a tad rich, what are the boost #'s at those rpm/afr numbers?

doesn't look like you need to upgrade injectors

 

At this point you are more than rich enough.

Do you have more specifics on your AFR numbers(decimal points) and boost levels?

IF anything you could lean it out slightly with less fuel pressure(or less meth), BUT you are surely safe at this point.

 

Nuff NUff and 86Z thank you for the intelligent replies (as opposed to the other).

my boost levels measured last fall (I am assuming I am a little lower now since I have installed headers this spring)
3000rpm 3psi
3500rpm 4.1 psi
4000rpm 5.2 psi
4500rpm 6.3 psi
5000rpm 7.54 psi

I will measure boost later today (max boost 6.82psi @5200rpm- change from stock manifold to dyno don headers)

I have a progressive water/meth (50/50) controller on at 2psi. Injection rates are 2.1gph @3psi, 6.4 gph @5psi, 10gph@ 7psi

PS. My son was reading the afr gauge while I was recording the rpm so it was difficult to get exact decimals

 

No problem! That's what the site is for!

What is your timing? stock? If so, I'd keep it as is and ride on.

The only other option I'd even consider would be to put in the 30 lb injectors and remove the meth(mine picked up by removing meth and upping the injector duty cycle), but then you'd have to get the chip tuned to compensate for the richness you're gaining by having the meth on the car(more headaches)

 

It honestly depends on your duty cycle, your current injectors might be keeping you in the richer/safer area, but if they are pegged while doing so, then it would be wiser to consider larger injectors w/new prom. 30# injectors are good for up to 370/400-RWHP in your LB9, anything less than that honestly defeats the purpose with a blower. I say switch them, you'll be glad that you did down the road...

 

with those boost levels, and a stock bottom end i would stay around mid 11.0-11.5 afr levels to keep the cylinders cool.

i'm running meth and 42lb injectors, i shoot for 11.3 - 11.5 afr range at 14#'s

they make all different size nozzles for meth