yet another thread about 660cc vs 720cc (scot gray inside)

[trinydex]

The GT3076R and AFC work pretty good. That is called the Dr. Gray Stage 2 setup. I recommend the Denso 660 injectors, AFC, EGT gauge with the probe mounted on the #1 exhaust runner, walbro fuel pump, turbo back exhaust, aem intake, upgraded intercooler and piping, HKS 272 cams and cam gears set to -2 -2 with the GT3076R turbo.

Should make around 380-400awhp on pump gas and 450-480awhp on race gas.

i have a question about this... how come the 660s? why not 720s? i'm asking czu i'm wondering if i can still get 20 degrees at redline using 660s and a pump.

[Blak94GSX]

The Denso 660s work good on most cars running straight 91 octane. The Denso 720s would be a better choice for 100 octane or running a mix all the time. The 720s also work on 91 with some cars, but not so good with others. So the 660s are a safer bet, but the 720s make more power under ideal conditions.

[trinydex]

if all else fails could always just fatten up the areas that are running more timing to tone some of the timing down right?

[Blak94GSX]

Yeah but that can mean running so rich it misfires.

[trinydex]

damn.... so 660s are a safer bet? how much top end timing can i expect from 660s plus a pump?

[Blak94GSX]

Well I'm not saying get rid of your 720s and put in 660s... If you have 720s great.

Actual timing numbers vary from car to car, but yeah somewhere around 19-21 at the top.

[trinydex]

i don't have injectors yet... seein' which ones need to be gotten. so 660s it is?

[trinydex]

last question, could you just tune the 720s for max timing and run a decent afr and then just let hte ecu take timing away if it's too much timing advance? or is that dangerous basically, cuz i read in another thread that you said that might be good for pump gas... but i don't wanna take anythin goutta context.

[Blak94GSX]

If the ECU pulls timing out, it pulls out a LOT, so you end up with no timing. Get 720s if you are going to run 2 maps, one for 91 and one for 100 unleaded straight, and you want to get the max power out of the 100. Get the 660s if you want to get the max power out of straight 91.

[trinydex]

sweet thanks scot.

[dreamevo]

Question on Stage 1: Why 720cc in stead of 660cc injectors?

[trinydex]

it depends on your setup... if you want to go race gas eventually or not (turn up boost). 720s don't always work with every car... the amount of fuel that needs to be removed can add too much timing (safc tuning). basically if you have a stout car that moves a lotta air then 720s may work fine even on pump gas. but if your car is a lil weak then 660 is a safer bet and is always a safer bet.

[C-Spec]

all of us have different opinions. your best bet is call up who ever you end up picking to tune your evo and ask them. O0

[GokuSSJ4]

im sure with having Open Ecu flash this can be change, since it allows you to manipulate : timing and the fuel map table when it comes to different injectors... Also being able to have full control of the ECU vs before with the SAFC should make a huge difference now when choosing injectors size for different set ups.

[trinydex]

uhm... ot...

this is just scot's recommendation based on his stages. he likes safc tuning... it's on the fly etc keeps the ecu virgin.

if you want to mess with the ecuflash yourself then you may have to rescale for the injectors which may or may not involve injector dwell times.

[Mike W]

Yes, or a guy that will be on 91 99% of the time and just an AFC, 660s are all you.

For an AFC only guy that keeps the boost low on 91 and does his playing on higher octane, then 720s are better.

If you are talking mixing in flash tuning only or flashing and AFC, then Denso 720s work fine even the cheaper RC Engineering 750 are fine.

Mike W

[earlyapex]

I run 720's with ecuflash + ECU Plus.

I have the 720s scaled via ecuflash which work great. Drivability is MUCH improved over when I had 720's and just SAFC. Huge difference. Even if you are in love with SAFC tuning and don't want to tweak the ecu with reflash, it's worth the $90 for the tactrix cable so you can scale larger injectors correctly. You also have the bonus of other nifty things like raising idle, raising rev limiter and playing around with the two step rpm.

I use ECU Plus on top of my 91 octane ecuflashed ecu like a glorified SAFC when running race gas, I lean it out a bit and add more timing.

[GokuSSJ4]

uhm... ot...

this is just scot's recommendation based on his stages. he likes safc tuning... it's on the fly etc keeps the ecu virgin.

if you want to mess with the ecuflash yourself then you may have to rescale for the injectors which may or may not involve injector dwell times.
i understand being scot's recommendations, but i also notice the date that this was posted on.. By now he has full control of the ECu due to Open ECU flash so maybe somethings have change or maybe they havent.. having control of the ECU via flash will change things in perpective.. remember that Scot is able to tune both SAFC for minor changes and scaling injectors and adding timing via flash combination. Reason why i decided to make a comment about it

[trinydex]

please read mike w's post

[GokuSSJ4]

please read mike w's post
bah!
miss it ! since i notice what you had posted and decided to answer prior to seeing Mike W el mero mero mas chingon de RRE post .. sorry :(