Just making sure for a TPI motor the best PSI Rating is normally 49 PSI at WOT or without vaccum right. Is that strickly for stock motors? I don't have any crazy mods check out my sig, please let me know if i should add more psi or less then 49 psi at wot. I know it messes up the spary patern with to little or to much psi. Also my fuel pressure just bumpping the key forward not running is about 45psi that good to?

 

stock is 37-42 psi with vaccum off according to camaro performers magazine. they say bump it to 47-52 psi on a dyno with a wideband o2 to get your tune dead on the nuts...around 13:1 a/f ratio

 

Well i hit up a vette site, for some reason the PSI should be about 44 at WOT lower then an F body, maybe becasue the vette has bigger injectors? not sure but anyway. i find it strang but eirther way thats where i'll start then i'll bump it as needed. But the AFR should be about 13:1 you said. Well after data logged my AFR is about 14.70 avg. Correct me if i'm wrong please the lower the AFR the leaner it is right? the higher the AFR is the richer right? Is the 13:1 range my target for best preformance? Reason being is my BLM's are reading richer rather then normal. So i think it's becasue i had my Fuel pressure at about 52 PSI at WOT. so i think i'll need to put it a 44psi at wot then data log. if you could please help with the couple questions above it would be great please.. BTW a data logger should work as good as a Wide band for the most part right?? thanks again.

 

ive actually got the same quesiton. I datalogged as well and got the same...14.7:1. I believe the higher you go, the leaner. But someone on the forum told me 14.7 is good. Let me look for the post.

 

With a mild engine, 48-49 is a pretty good bet. I run 45 on the street then bump it up to 50 at the track.

 

https://www.thirdgen.org/techbb2/sho...hreadid=342117

here's that post

 

14.7 to 1 is optimum for cruise and idle on a warm eng. The O2 sensor helps the ECM maintain this mixture.

The lower the first number, the richer it is.
Each eng is different but 11.5 to 12.5 is roughly where you want to be when at WOT.

BLMs above 128 indicate the ECM didn't initially deliver enough fuel and it had to add fuel cause of what the O2 sensor reported.

BLMs below 128 indicate the opposite.

BLMs in open loop are meaningless.
When at WOT, the ECM enters open loop.

Nothing will replace a wide band O2, except maybe reading the plugs and that's an art.

All the factory O2 sensor voltage will tell you is; if you are above or below 14.7 to 1. It won't accurately indicate how far you are from 14.7 to 1...

Not sure what you are seeing in the datalog to indicate a 14.7 to 1 mixture. Maybe you are seeing what the "commanded AFR" is. This is what the ECM is using for a target, not the result.

 

Did you notice an increase in mph when you turned it to 50 Psi?

 

Sorry you are right it is the target range of afr.

at 50 psi. gas miles are at about 23mph.

 

It was good for about .8 mph run after run, or about 6-8 hp or so, et didn't go down hardly, but it shows the engine making more power.

 

kinda a random question but it kinda relates.

If I had 36lb injectors should I still bump up the pressure? or should I lower it from stock? thanks

 

On what motor? Stock L98? If so, those injectors are too big. I imagine you would have to get a custom chip, or turn the fuel pressure down.

 

mods engine wise are 52mm TB, SLP runners, eddlebrock base plate, 36lb injectors, FP regulator, roller rockers and SLP headders. I was told it had a custom chip burned by the original/previous owner.

when I checked the FP it was right at 42 psi. The previous owner said it was set that low to get good gas mileage. I have read the tech article on here that said you could bump it up to 50psi for max gain. I have it set at 46 right now.