tunning vs boost psi

[cbr600teardrop]

what psi should i run to get the most out of the 16g big turbo iv read some where between 20-25 psi does that sound right? ill send my dsm chip back off and have it remapped what fuel pressure should i run ifc 650cc i was going to run it at 55 psi that's at 80 to 85 % duty cycle @ 723cc at 8.1:1 compression ratio other mods listed in profile.

 

[Rob10_99]

55psi base fuel pressure?

Running regular 92/93 pump? There's a lot of variables, 20psi is pretty good for a 16g on pump.

 

[jeffo]

Your chip is already remapped to ~24psi. 55psi is rather excessive base fuel pressure, even for a 255 pump. At 80 psi (55psi base + 25psi boost) the 255 pump output drops dramatically:
Stealth 316 - Fuel Pump Upgrade Guide
Even a rewired Walbro 255 HP pump can't supply the 174 liters/hour that 723cc injectors would need at 100% duty. At the most I would shoot for 47-48psi base fuel pressure.
Unless that is the EVO3 16G, its not very efficient much over 20psi anyway.
How much boost are you running now? Are you having issues with the chip tune? Even at 37psi 650's should be enough for well over 20psi on 93 octane.

 

[cbr600teardrop]

its not put together yet still gathering parts trying to find out what i should have my chip remapped as and how much boost should i shoot for to keep the turbo Efficient and what should my fuel pressure to run a high boost on 650cc injectors on pump 93 octan and walbro 255lph hp rewired and 2g mass

 

[Black_Bullet]

My evo316g felt best on pump at 25-26psi. Night and day difference over just running 20-21 psi.
Id shoot for that psi with a low 11 afr and then tune the timing accordingly after that. On ethanol the 16g continued to make more power even beyond 30psi. Not very efficient beyond 30psi but depends how far you care to it i guess, my 16g is dead now btw ... Something else that made the 16g feel better is when I ran a cold air intake into the fender well w/ a gm maft blow thru setup, it held boost longer to redline after doing that. I wouldnt mess with the fuel pressure too much, on regular pump I think your 650s will be fine with a 2g fuel pressure. If you do increase it you can get more flow out of the injectors ( less from the pump) but you have to have the chip burned accordingly. But fwiw I run the n/t fpr with a 47psi base fuel pressure and 850cc FIC's and a HP 255lph. Anyways Just throwing out some ideas for you...

 

[cbr600teardrop]

thanks i think ill do 50 psi on my fuelab afpr and have my chip set for that and the 2 g mass and 8.1:1 compression ratio. should i do the high speed closed loop

 

[jeffo]

The highspeed closedloop is only for guys who want to drive 85 mph+ on the highway, to help mpg.

 

[Black_Bullet]

The highspeed closedloop is only for guys who want to drive 85 mph+ on the highway, to help mpg.

With that setting I used to run into knock hiccups in 5th gear because the 16g spooled so fast id be literally riding down the highway in boost the whole time above 75mph. At least I think its related to that extended closed loop? MPG did improve though.

 

[mikelv]

My evo316g felt best on pump at 25-26psi. Night and day difference over just running 20-21 psi.
Id shoot for that psi with a low 11 afr and then tune the timing accordingly after that. On ethanol the 16g continued to make more power even beyond 30psi. Not very efficient beyond 30psi but depends how far you care to it i guess, my 16g is dead now btw ... Something else that made the 16g feel better is when I ran a cold air intake into the fender well w/ a gm maft blow thru setup, it held boost longer to redline after doing that. I wouldnt mess with the fuel pressure too much, on regular pump I think your 650s will be fine with a 2g fuel pressure. If you do increase it you can get more flow out of the injectors ( less from the pump) but you have to have the chip burned accordingly. But fwiw I run the n/t fpr with a 47psi base fuel pressure and 850cc FIC's and a HP 255lph. Anyways Just throwing out some ideas for you...

You ran 26 pounds of boost on pump gas?

 

[Black_Bullet]

You ran 26 pounds of boost on pump gas?

Yes, with supporting mods, a big intercooler, and proper timing that shouldnt be so surprising. The 26psi was mainly through the lower rpms and mid range, it would taper off to 24psi by redline. With 1g pistons timing started low around 10 degs, seen mid teen degs in the midrange, and peaked at 19degs at 7k by the time boost tapered to 24lbs with a solid 11.3 AFR at wot across the entire pull. Never was dyno'd in that state of tune but it gave me the best results as far as butt dyno went, and Id typically never see anymore than 3 to 5 counts ( not degs ) of knock through a full 4th gear log which is nothing. With a little less timing down low I could've had it hitting 28-30psi on pump but the dramatic reduction of timing to do that didnt warrant any gains as the turbo began getting too hot and the trade for psi vs timing deg was no def longer linear.

 

[LandoAWD]

OP: I'm tired of clicking the "Warning" button for your poor grammar attempts. Clean you posting up, or expect a lock.

 

[mikelv]

OP: I'm tired of clicking the "Warning" button for your poor grammar attempts. Clean you posting up, or expect a lock.

Not to be a smart ass but, I think you meant "your posting", correct?

Yes, with supporting mods, a big intercooler, and proper timing that shouldnt be so surprising. The 26psi was mainly through the lower rpms and mid range, it would taper off to 24psi by redline. With 1g pistons timing started low around 10 degs, seen mid teen degs in the midrange, and peaked at 19degs at 7k by the time boost tapered to 24lbs with a solid 11.3 AFR at wot across the entire pull. Never was dyno'd in that state of tune but it gave me the best results as far as butt dyno went, and Id typically never see anymore than 3 to 5 counts ( not degs ) of knock through a full 4th gear log which is nothing. With a little less timing down low I could've had it hitting 28-30psi on pump but the dramatic reduction of timing to do that didnt warrant any gains as the turbo began getting too hot and the trade for psi vs timing deg was no def longer linear.

Wow, that's awesome. No, I wasn't trying to sound conflicting or surprised, just wondered how you did it. I have every supporting mod I can have and never was able to get those kind of counts or advance on that much boost, via low octane fuel.

I mean at a certain point regardless of retard, that much air is going to ingnite the fuel. I mean a lower octane fuel will have a lower ingnition point. The best and safest I've ever seen anybody run regular unleaded gasoline at was 22 pounds. Beyond that, without some sort of meth injection kit or something to cool things down a bit, that gas is going to flame early on you.


I was able to run 24 psi consistantly on a stock 2g bottom end but anything more than 24 psi was pushing it. However, this was with 110 race gas. I wouldn't think of running pump on that kind of boost consistantly. I was tuning fairly conserative, but was still getting 3-4 degrees of knock. That was with total timing of 19 deg and 2 degree advance on Link. That was the smoothest curve I could get, anything more than that was pulling hard.

I just find it pretty interesting that you could run in excess of 25-30 pounds on pump gas without blowing anything up, that's all.

 

[LandoAWD]

Indeed I did. A missed key =/= toolshed status.

 

[mikelv]

Anyway, I figured this thread should be merged with the other 10 million asking about how much boost should be run on "X" turbo...I'm surprised you're letting this one hold up in the tuning and engine management section.

 

[knochgoon24]

...I just find it pretty interesting that you could run in excess of 25-30 pounds on pump gas without blowing anything up, that's all.

I think to key to all of this is airflow. I'm still running stock cams and I've been able to run 25psi on 93. I doubt that I'll be able to do that once the HKS 272 grinds go in. I haven't been too aggressive with the timing or AFR though. It's my DD.

 

[1fastlaser]

High boost is completly capable on turbos on straight 93, it just comes down to making sure everything is right, and knowing what your doing with the tune. Im running 34psi on straight 93 pump gas now. No meth or anything you can think of. Who says ebay intercoolers cant rock .

 

[knochgoon24]

I'm rocking an eBay intercooler.

 

[My1GLaser]

I've been running 28 psi on an 18g for the last year and a half.

9:1 CR, 11.5:1 AFR, 19* timing, pump gas with no meth. I'd push a 16g to 25psi without thinking twice with timing control.

 

[JayRolla]

High boost is completly capable on turbos on straight 93, it just comes down to making sure everything is right, and knowing what your doing with the tune. Im running 34psi on straight 93 pump gas now. No meth or anything you can think of. Who says ebay intercoolers cant rock .

Yea but we are talking a 16g which is different than larger turbos. Me personally only could get 20psi, 10.8 afr at 18* timing on my 16g on pump.

On e85 I see 32-34psi, 24* timing and 12.0 afr with no knock. My 6 bolt was knock crazy on pump gas.

To the OP I would start at 20 psi and say 15-16* peak timing. Then slowly add boost till u see knock. If your still ok on knock slowly add timing. Boost always makes more power than timing.

 

[1fastlaser]

Yea but we are talking a 16g which is different than larger turbos. Me personally only could get 20psi, 10.8 afr at 18* timing on my 16g on pump.

On e85 I see 32-34psi, 24* timing and 12.0 afr with no knock. My 6 bolt was knock crazy on pump gas.

To the OP I would start at 20 psi and say 15-16* peak timing. Then slowly add boost till u see knock. If your still ok on knock slowly add timing. Boost always makes more power than timing.

Oh ofcourse. Hot air, efficency, timing play huge rolls. Cylinder pressure being one of the key factors in it all. Every car is different, but with some knowlege big power is possible on 93 octane.

I like seeing guys pushing the limits. Right now Im tuning a buddies car, dsmlink, 780s, evo 3 16g, delta 272s, built motor. Trying to see what kind of numbers we can get out of it on straight 93 octane.

 

[Black_Bullet]

Yes^ you just have to pay attention to detail on cars pushed like that. From the tune to the hard parts down to the type of spark plugs being used. ( NGK BR7ES non projected tips worked best for me.) I have 272 cams btw, the cams didnt make too big a difference in tuning timing.
My car was tuned like that for a year, that motor had 120k and died because of spun main bearing. Now given, I had 1g pistons in there, tuning high boost is even easier on lower compression. A bit harder to pull higher boost numbers on CR's higher than the 2g. On my friends 60-1 built talon with 9:1 CR I tuned him but at 27psi I couldnt see more than 11-12 degs of peak timing on 93oct or it would knock bad. On ethanol up to 18degs timing it became a animal... Every car is different.

 

[mikelv]

Yeah guys, I haven't messed with a 16g in damn near 10 years. I have a bunch of different turbos, but my FWD daily that I posted my dyno stats on here ran a 54 trim, old school Frank 3 ported/clipped 10deg. I'm not a huge turbo guru, but I know I could push that much air through it. I was able to get 24 psi on race gas on a stock 2g motor, (plus cams) and that yielded 420 hp....but I couldn't keep things cool enough on that boost level with a low octane fuel. That was a big ass intercooler as well...I was able to advance 3 degrees across the board and had total timing of 22 deg I believe, smooth curve, no knock.

Curious, but what kind of numbers are you guys getting from 30 pounds of damn boost on a 16g, and is it even worth it? I mean honestly, I'm not a 16g expert or anything, but 30 pounds sounds a little out of the efficiency range. That and you really have to have control of that puppy, with at least Link.

I have a video on here somewhere I can pull up, where we got 456hp on a 1g stock bottom/top motor (dynojet) and 400 even on dynomat. That was a 16g on 22 pounds I believe....all on race gas though.....it could have been 24 psi, I'll have to check......

Hell I ran high 500's on 30 pounds with the AWD

 

[JayRolla]

I have not hit the dyno but link is estimating 405 hp and around 430tq on stock cams. 22psi too 30psi on my 16g was like a night and day difference. I like to spike my turbo to around 32psi which helps it hold more boost to redline and a lot of tq comes on real early in the power band.

 

[mikelv]

I have not hit the dyno but link is estimating 405 hp and around 430tq on stock cams. 22psi too 30psi on my 16g was like a night and day difference. I like to spike my turbo to around 32psi which helps it hold more boost to redline and a lot of tq comes on real early in the power band.

You can run 30 psi on a 16g with pump gas and not set that shit on fire pre-mature? I just don't see how you guys can make pump gas not pre-inginte. Either the car will pull the shit out of the timing, or it won't even matter, but beyond 22 psi, I don't think I've ever run anything like that with 93 or lower.

Man, you guys are better than I....I'm going to try that with a test car.

If you can get cars with your setup to run 30 pounds all day long on pump, then why would anyone ever bother with race gas?

 

[jrohner]

He runs E85.

I currently run a flat 28psi bottom to top. My car doesn't feel like it has much power with the boost any lower; I only have like 118psi of compression in #2, so that's probably part of the reason.