Whats injectors to go with these mods?

[highboostintsi]

I have been looking everywhere and talking to different people, and I don't get the same answer everytime.What size injectors to go with the following mods:big fmic,16g,255 walbro,fpr,2g mas,turboback. THe car will be tuned on an AfcII. thanks for the help

 

[Jason84]

680ccs

 

[project_tsi]

650's, or 680's would be plenty for an Evo III 16G. I also strongly reccommend picking up an eprom ecu and keydiver chip w/ built in injector compensation.

 

[Eastwood95]

hmmm, i thought 550s would be ok, unless you want to run high boost on low octane.........check out road race, there's a few articles and charts that might help you decide.


http://www.roadraceengineering.com/ecltechtips.htm

http://www.roadraceengineering.com/eclfuel.htm

 

[Jason84]

550s are to small... you will max them out

 

[RiceKiller_TSi]

I run 580's. Just bumped up the fuel pressure and VOILA! 22PSI, low idc, no knock.

 

[Jason84]

yeah check out your IDC...

my friend was running like 22-24 on race gas and his IDC was 112%... with good 550s.

bumping up the fuel pressure is not a good way to tune a car.. better off buying the right parts for your car instead of being a cheapo.


im running 680s with walbro 255 evo 16g an a 9:1 motor and its running really good. with a gm mas and trans and safcII

 

[RiceKiller_TSi]

bumping up the fuel pressure is not a good way to tune a car.. better off buying the right parts for your car instead of being a cheapo.

Obviously your friend can't tune an engine if he's at 112% on race gas. Especially since I run 21psi daily with plain ol pump gas and and zero knock with no more than 85% idc. Don't compare my tune with your friends because not all cars are the same anyhow.

Btw most injectors are flow tested at 43psi (which is what my fp is) and not 37psi (which is what stock 1g fp is) so there is nothing wrong with running injectors at the pressure they are rated for to get the rated flow out of them.

As for being a cheapo, well, you can get your hand outta my pocket unless you want to come and turn some tricks and pay my bills.
Secondly, 580cc injectors and 650cc injectors cost about the same price wise guy.
I chose 580's because they are easier to tune with using the maft setup.

Jump into this forum and get read up. This guy knows fuel injectors pretty well and you need some learnin'.
http://www.otsmotorsport.com/dsmchips/viewtopic.php?t=286&highlight=fuel+pressure
Check out post #7 twinkle toes.

 

[DragSourceTsi]

get 660/680's.

IMO 85% IDC is to high. Why have to by injectors twice. When tuned with an aem 660s suported 481hp wiht a green?? 660's are great afc injectors!

 

[RiceKiller_TSi]

get 660/680's.

IMO 85% IDC is to high. Why have to by injectors twice. When tuned with an aem 660s suported 481hp wiht a green?? 660's are great afc injectors!

I agree with^^. But even more so if you get your ecu chipped. Piggybacks suck more the larger the injector you use and throw off your fuel maps just that much more since they are essentially lying to the ecu.
I don't have a fmic which I why I run more fuel to keep from knocking at 20+ psi. The idc would be lower if I pulled fuel but my knock would go up. When my fmic is installed I should not see over 80%idc.

 

[MyBeatGSX]

I'm running 550's on a nearly identical setup. Base fuel pressure (no vacuum) is like 39psi. I had to take out 28% fuel at redline to hold an 11.5:1 afr. Guess what that means? They're nowhere close to maxed out.

I think 650-680's would be overkill for 300whp, which is the higher side of realistic power for a 16G. Unless you're shooting for some pig rich 91 octane afr. Stay away from huge corrections on the SAFC.

 

[DragSourceTsi]

I would say the throw off the timing more then anything. You telling the ecu that there is less air coming in so it has less fuel as well. The problem is less air = more timing to the point of knock. 660's seem to be nice and happy with an afc little timing pump and leaning it out helps make power!

 

[DragSourceTsi]

I'm running 550's on a nearly identical setup. Base fuel pressure (no vacuum) is like 39psi. I had to take out 28% fuel at redline to hold an 11.5:1 afr. Guess what that means? They're nowhere close to maxed out.

I think 650-680's would be overkill for 300whp, which is the higher side of realistic power for a 16G. Unless you're shooting for some pig rich 91 octane afr. Stay away from huge corrections on the SAFC.

You say that they are no where close to maxed out whats your IDC?? Are you never going to upgrade turbos?

I would stay away from huge corrections on an AFC too, but 660s aren't a huge correction.

 

[highboostintsi]

thanks for all the feedback, now i need to find some slightly used 680's. is there a base tune that i can set on my afc so the car will run right, i need to drive it about 20 mins away to get tuned?

 

[Ultimatedsm]

Get a DSMLINK and run whatever size injectors. With 300WHP I would get 650cc injectors because there is still a safety margin left just incase if you want to squeeze a little more power and they will never max out on you. You know pushing stuff to the limit is when stuff break, so always have 1 injector size bigger then what you need for safety reasons.

 

[MyBeatGSX]

You say that they are no where close to maxed out whats your IDC?? Are you never going to upgrade turbos?

I would stay away from huge corrections on an AFC too, but 660s aren't a huge correction.

The 550's will suffice until this motor either blows or needs rings. I have bigger plans for the car, but not with this stock motor. So yes, I will be staying with this turbo until then.

I don't know my duty cycles, repair issues have postponed me getting a logger. But really, what does it matter. I'm pulling almost 30% of the fuel just to hit 11.5. That's a LARGE safety margin. So what would I have to pull to make 680's hit that same arf? 40%? 45%? That's WAY too much timing for me.

Why does everyone have to assume people will always upgrade? If you're going to spend $600 on an EvoIII 16G and then throw it out in six months to upgrade to a $1,000 20G, plus another $500+ for an external gate and new or modded manifold, are you really worried about dropping $280 for new injectors? Picking the right turbo the first time around should be the #1 importance. And if you aren't going to upgrade, then why go bigger than nessesary?