I am currently running lean, 12.5, at 6400 rpm and in last ref;lash lowered my redline to 6400 and generally stay away from that rev range.

This happened when I got Y pipe, highflow cats and a 9 psi pulley.

I am currently picking up 440ccm injectors.

Will I be able to fic my leaness just with injectors?

My fuiels system currently is the ATI FMU plus stock pump in tank plus ATI inline pump in series.

currently the ATI FMU is maxed out.

I am hoping to not have all that ripped out ..

Will I need a fuel return system?

Umm your terminology may be different but 12.5:1 is rich not lean.

well it was 12.5/12.6 at 6400rpm under load..

Most folks like to have high 11's for boosted application..

I hope injectors and maybe subsituting a walbro 255 lph for the stock pump(good idea?) may help give me the extra fuel I am running out of at top end..

Fred..

DOH wasent paying attention to the 6400 part. Honestly first think I thought when you said you were still running the factory fuel pump I was a bit taken back. I figured you would of upped it.

It has factory pump plus the addtional ATI inline pump thats controlled with the ATI FMU (for tuning)

Its this set-up thats currently maxed out.

Talked to another tuner and he also said emanage <is> a must to drive these bigger injetors and they <need> a fuel return system for consistent fuel pressure and stable tune..

Soooo I now have the choice vs spending an addtional $3000 ( on top of the $4000 I just spent which was on top of the original install)This even includes some substantial discounts.

a)go back to a 7 psi pulley save 2.5k (will have ton pay to have old pulley back on and at least anominal fee for retune maybe more) .Have redline back at least to stock or even higher= fewer shifts than option b)This savings could be used on Koni yellows or brake lines/pads and a leatehr kit and have money left over..b) have my redline dropped lower yet to say 6200 or even 6100 so I am totally stayng away form the danger area, this is an even cheaper solution than a) and I will retain thatpowerful midrange boost.c) Go all out with fuel return system bigger injectors,Super emanage Walbro 255.This will also give me back my beihnd the passenger seat "glovebox" as I currently dont dare use it, with the FMU and sliders in there.This is the mostn expesnive solutuion ( 3k) <but> I suppose I could still find the money for the other mods I just have the feeling that costs are spiralling too much for my liking..

Fred, 12.5:1 is dangerously lean for a boosted car. How are you measuring that anyway? Do you have a wide band installed in your car?

And I would go with the full fuel system, including the return line. Either that, or cut back on boost. Try to compensate for lack of fuel flow is only going to blow up your motor in the long run, which is gonna cost you way more than a return line.

You can set up a return fuel line for a lot less than you said. You just have to get creative. Somebody posted on b15sentra.net a few years back how to run a return fuel line, a DIY FAQ. Look it up, if you can find it.

Whatever you do, don't keep running a 12.5:1 A/F ratio on a boosted motor!

And if it goes any leaner....stop the engine before it stops itself!

Torry:Thanks for the info!!On a side note the 12.5 is only at redline , whicyh is now lowerdt o 6400 so seeing more like 12.3 and I always shift at 6200 when racing which is at 12.0.

The rest of the band is high 11's.

SO my current set-up stuill works.And if I go with a huge expense i am thinking of maybe getting a built-up engine with a 11 psi pulley

Dude.

12.5 - 12.8 is fine as long as you are pulling you're timing correctly.

http://www.forgedinternals.com/main.htm

Here is the kit to fix you're issue. This should take care of the drop off in the upper range.

http://www.forgedinternals.com...age=1

I like people like Fred here. He is destroying his warranty peice by peice for a good cause. To see just how fast a 350z can go before it pops. In this company though I know when it pops it will just get something better. Have fun Fred and "Enjoy the ride".

SHIFT_Fred

fred you could save your self a ton of money and work by going with a methanol injection kit, or even a water injection kit would help a ton.

most run a 50/50 water/methanol mix. the water cools the air entering the cambers and the methanol raises the octane greatly. this would make your current conditions plenty safe

im installing an SMC enterprises kit next week on my 240. the small half gallon tank lasts for a decent amount of time depending how much you boost. the SMC kit comes with a low fuild level light to warn you. the kit retails for $400.

it can be set to come on a certain amount of boost. the pump speed can be controlled so you dont bog

just a thought for yourself

ill be using it to run 20-25psi with pump gas out of my pt61

Question: How are you guys measuring your fuel ratio? And do you feel it is a 100% accurate way of measuring it?

I currently dont have an AF in the car my numbers are from dynotunes..

Thanks for all the great advice guys!