650cc injectors w/ EVO III 16g?

[kelvinb]

550's + 2g MAF = very little SAFC tuning

 

[timloomis]

Thats what I was wondering since the 550's and a 2g maf are so close. I wish I had some 750's laying around so I could log timing.

 

[kelvinb]

You could accurately correct 750's/2g maf/afc

However, you could do 650's I'm sure with little issues.

 

[BGRIPTP]

550's should be plenty, however, the price difference isn't much if anything, why not just go with the 650s?

 

[dsm-onster]

Now would a 2g maf on a 1g cancel that out? Because the 2g maf and 550's almost cancel eachother out, would that make it possible to run say, 750's, on a 1g with an afc?

2g maf + 550s = still a higher timing table. This still only fools the ecu into seeing a lower airflow than is truely there. So fooled, it runs on a more aggresive lower airflow timing map.

So, still one cannot run more than 650s with an safc (no matter the maf) without dealing with seriously aggresive timing issues. You can't get around fooling the ecu when you're fooling the ecu. You have to make it smarter. Or be capable of handling the consequences. You could run enough mass flow to push the ecu to see the lowest timing map. But, what do you tell it at part throttle?

550s are not enough for an evo3 16g. 650s are. As ShapeGSX pointed out a long, long time ago .

 

[demografik]

At 20psi on pump gas, I'm at 108% duty cycle with my 550s. At 22psi on race gas, I'm at 95% IDC. The people who have run 10s on 550s just had their injectors on all the time. It is better to have finer control.

there's a reason adjustable fuel pressure regulators are adjustable

 

[dsm-onster]

At 50 psi base fuel pressure, 550s flow 590cc. 590cc injectors are good for 371 CRANK horsepower at 100% IDC. It takes 61 psi for 550s to flow lik 650s !!!

At 50 psi base fuel pressure and 25psi boost, a walbro 255 HP fuel pump flows 45gph or 170lph. 170lph is good for under 450 crank hp. About as far as you can go with an evo3 16g. At 61 psi fuel pressure (550s tht flow like 650s), the 255hp flows 132lph. Good for only 348 CRANK hp. 650cc can be pushed to to 95% IDC with the evo3 16g as Shape demonstrated. 348crankHP is definately not at the limit of the evo3 16g.

You can raise the fuel pressure high enough for 550s to flow enough for an evo3 16g, but your fuel pump will fall short. You can raise the fuel pressure enough for the fuel pump to be just enough, but 550s will still not flow enough for an evo3 16g.

A better injector choice like 650s would be just as easy to tune and allow up to 420 crank hp at stock fuel pressure. And the same walbro fuel pump would be good for 500hp at 25psi boost.

The only way to get around this is to greatly manipulate your brake specific fuel consumption. . . Which takes LOTSS more money than upgrading injectors.

It IS better to have finer control.

 

[romeen]

Matt, in your opinion do you think I would be able to get up to around 24 psi on an EVO3 16G using 550's with the addition of water injection. I understand there are variables which make it impossible to predict exactly but I'm still curious for your speculation. I have a rewired 255, AFPR at stock BFP and we have 92 octane here in WA.

Also, since I have an internally stock 6 bolt with the 7.8:1 pistons along with the less aggressive timing of my 2G ECU (piggyback fuel control) shouldn't that allow for more leeway for tuning?

 

[dsm-onster]

Well, concerning timing and compression, the opposite will extract more power from less fuel and allow 550s to be pushed farther than .60 BSFC. Use a dyno to find MBT and run higher compression. With a good lean mixture. All this can be done with the proper water/meth injection flow. But also, a quicker burn (a properly designed high compression chamber) will yield honda-like BSFC and actually help fend off knock. The 4g63 head chamber is pretty good for this. You just need a piston top that works with it. Stroker guys who know what they're doing do this. They usually run at least 8.8-9:1 CR or much higher.

But at .60 bsfc, you'll have to run no more than 50 psi base fuel pressure for the sake of the wally 255hp. Four 590cc (550s at 50 psi) injectors flow 3.75 lbs/min fuel. At 12.5:1 a/f ratio,yu can run 46 lbs/min. 12.5:1 is about where peak toque occurs. So better BSFC is definately possible with running that lean alone.

Of course as you've alluded, there's no way in he!! you can run that lean without water injection at 25 psi and even a stock 2g timing curve.

. . .To add, using 93 octane, I've pushed 450s at 50psi base fuel pressure to 22 psi tuned at 12:1 a/f ratio with the wally. With water injection. And stock 1g intake mani/head/cams and 6-bolt block and small 16g. I didn't feel a difference between that and 19-20psi. But it held 12:1 to redline. With 680s and 11:1 a/f ratio and less water, I did feel a difference at 22psi vs 19-20. A little water can go a long way. A bit more water can make a huge difference in how much you put down to the wheels.

 

[romeen]

Just to make sure I understand correctly, the relatively low compression of my pistons coupled with the conservative timing maps of my ECU should allow me to run a little bit more boost than otherwise expected, correct?

I am under the impression that tuning for higher boost/lower timing generates more power than lower boost/higher timing. Is this right?

As far as fuel pressure I hadn't really planned on running more than the stock BFP of 43-44 psi but I guess I'll have to see how far I can get with it before deciding whether to increase the FP or not.

 

[dsm-onster]

From my experience, the statement "tuning for higher boost/lower timing generates more power than lower boost/higher timing" is much, much to generalized. I've seen one bigger FMIC than another change what was the best tune (boost, timing, a/f) for each with otherwise the same mods. I'm being vague because the statement is vague .

Having a very lean a/f ratio causes the fuel to burn at a more rapid rate. Thus advancing the timing may do no good and retarding it slightly may actually increase torque. You likely will find that you don't need that much timing to get good power. Again how much water/meth you end up having to add will determine this.

Do this to max out your fuel injectors. It worked for me. Tune for 12:1 a/f ratio with water injection and slowly turn up the boost to your target. If you have to pull more than 2 degrees of timing to keep knock in check, then you'll likely gain no more with that increase in boost from my experience. That's just the rule of thumb that 1 psi of boost does 50-75% better than 1 degree of timing with pumpgas (pump gas burns faster than race fuel: take advantage of it). Four 550cc injectors at stock base FP flow enough for 41 lbs/min at 12:1 a/f ratio. A likely number at 25ish psi at redline. If you can get no knock at 12-12.5:1 a/f ratio and you can run 22-25 psi, try advancing timing a little to see if you gain any power. If you don't, try lowering the water pump pressure a little at a time. The lowest water pressure before knock is the strongest tune. Whether or not you feel a hp gain comes from how much aggresive you can tune with the proper water or water/meth flow for 25psi.

 

[romeen]

Do this to max out your fuel injectors. It worked for me. Tune for 12:1 a/f ratio with water injection and slowly turn up the boost to your target. If you have to pull more than 2 degrees of timing to keep knock in check, then you'll likely gain no more with that increase in boost from my experience. That's just the rule of thumb that 1 psi of boost does 50-75% better than 1 degree of timing with pumpgas (pump gas burns faster than race fuel: take advantage of it). Four 550cc injectors at stock base FP flow enough for 41 lbs/min at 12:1 a/f ratio. A likely number at 25ish psi at redline. If you can get no knock at 12-12.5:1 a/f ratio and you can run 22-25 psi, try advancing timing a little to see if you gain any power. If you don't, try lowering the water pump pressure a little at a time. The lowest water pressure before knock is the strongest tune. Whether or not you feel a hp gain comes from how much aggresive you can tune with the proper water or water/meth flow for 25psi.

Good stuff!

Thanks.

 

[matt98eclipse]

Hey matt would it be easier to tune with the safc or maft on the PTE 680s? The reason i ask is cus right now im running the maft and my buddy wants to trade me his safc for it.

 

[dsm-onster]

The safc has more tuning resolution and divides the rev range into more incriments Siit will allow you to tune out a better curve. But getting it up and running should take the same effort. You have the same dead time and flow to dial in.

You'll have to buy a 2g maf to run any flow over 30 lbs/min, since you'll be back to running the 1g maf. Unless all you want to run is 300crank horsepower. Or you could SEVERELY hack the 1g maf. It has been done, but that's alot of work and retune when you already have a maf upgrade with the MAFT.

 

[matt98eclipse]

Thanks man So you think it would be worth it to trade for the SAFC or should i just keep my MAFT? All im lookin for is a high 12s to low 13s. You think its possible with my mods??

 

[dsm-onster]

Are you having problems tuning the MAFT? If not, then you're fine now. And you will have a maf you'll likely never overrun.

I ran 13.4 with a 1g maf. But there's no room for growth with an safc and stock 1g maf.

 

[matt98eclipse]

I just got done getting my head rebuilt and installing the new 680s so i havent even had a chance to see if im gonna be haveing tuning issues. I will be starting the car tommorrow so will see!