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Dyno tune advice

MX4

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Apr 9, 2001
Messages
780
Location
New Zealand

Hi all,
My car is currently in with a workshop to have the dyno tune completed. I am unsure about how much boost I should ask the tuner to use. Obviously o2 readings and knock will be a limit at some point. It will be running on pump gas (equivilant to 93/94 in the USA). I would appreciate advice from members on here with direct experience.

Engine setup is:
9.0:1 forged pistons
Aftermarket rods
ARP head studs
Cometic head gasket
ID1000 injectors
300lph fuel pump
Fuelab fuel filter and adjustable fuel pressure regulator
Forced Performance GT35R with 0.68 exhaust housing
Larger intercooler w/ 2.5" intercooler piping & Tial BOV
Degree'd Kelford 272 cams with dual valve springs
3" Exhaust
Standalong ECU

Cheers!
Ryan
 

tektic

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Dec 19, 2012
Messages
1,497
Location
ronkonkoma, ny
30-45 /ubbthreads/images/graemlins/wink.gif
gt35rcompress.gif


Edit: I don't think I'm reading that right. The tooner should know what to make of that chart though.
 
Last edited:

tektic

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Dec 19, 2012
Messages
1,497
Location
ronkonkoma, ny
40 lbs/min. Therese some computations necessary to get the psi. the turbo runs up to 79% efficient everywhere in that smallest center island. That's the sweet spot of the turbo and that's where it will be best utilized.

Is this a track car, Weekend warrior, or a dd?

--Edit--

Conversion factors:

(PR X 14.67psia) - 14.67psia = Boost
kg/sec X 60sec X 2.2046lb/kg = lb/min
m^3/sec X 60sec X 35.3ft^3/m^3 = CFM
CFM X .07 ≈ lb/min
 
Last edited:

92_talon_awd

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Feb 11, 2014
Messages
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Location
Knoxville, TN
Quoting MX4:
30psi on pump? Really??


I ran 30psi on pump for years on my talon. Never had a problem.
 

MX4

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Joined
Apr 9, 2001
Messages
780
Location
New Zealand
Quoting tektic:
40 lbs/min. Therese some computations necessary to get the psi. the turbo runs up to 79% efficient everywhere in that smallest center island. That's the sweet spot of the turbo and that's where it will be best utilized.

Is this a track car, Weekend warrior, or a dd?


CFM X .07 ≈ lb/min



Its a weekend warrior. I realise a GT35R is probably too big for a daily driver on pump, but I picked it up for a good price.
 

MX4

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Messages
780
Location
New Zealand
Quoting 92_talon_awd:
Quoting MX4:
30psi on pump? Really??


I ran 30psi on pump for years on my talon. Never had a problem.



And this was without knock, and safe o2's? And on what size turbo? It sounds like alot for pump gas (not that I dont believe you. /ubbthreads/images/graemlins/smile.gif )
 

92_talon_awd

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Knoxville, TN
Yup, no probs with either. click It was a garrett 70 trim.
 

prove_it

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Sioux Falls, SD
Probably didn't have issues with it because of tuning. Run more fuel and a little less timing and I'm sure it was happy at 30psi.
 

diambo4life

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Jul 7, 2013
Messages
315
Location
Edmond, Oklahoma
People have done 30-35psi on pump 93. It's all in the tune. /ubbthreads/images/graemlins/dunno.gif Start conservative...20psi'ish and work forward.
 

prove_it

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Sioux Falls, SD
Not all in the tune, you do need head bolts and a gasket that will hold the pressures. Also a lack of carbon build up helps a lot too. Other than that, it's the tune.
 

diambo4life

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Edmond, Oklahoma
Stock HG and the stock head bolts will handle ALL the power a GT35R will make on pump gas. It's been done....MANY times before. Tune is the key. /ubbthreads/images/graemlins/cool.gif
 

prove_it

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But for how long?
 

Wookalar

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Nov 27, 2013
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458
Location
Arizona USSA
From a safety stand point when tuning on pump gas wouldn't the "tuner" watch air fuel ratio first, or wide band o2 levels, then injector duty cycle, and then also take into account fuel pump flow rate? Then think about boost levels last.

There is a formula for hp power/fuel flow rate for pump and injectors.

I'm not a "tuner" but it seems like the air fuel ratio for proper combustion would be more important than how much boost you want to run. The amount of boost is a byproduct of the correct afr? /ubbthreads/images/graemlins/dunno.gif
 

prove_it

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You are correct. That's why you start out at a known good boost level. Say 15-20psi. Dial in your AF ratio, check injector duty. Once that's set then you can play with timing at the low boost. Find the sweet spot then take it back small notch(you can always add it back). This gives you a baseline for timing to avoid knock. Then you increase boost based on where your at. If injector duty is maxing at say 50% and the pump is barely working, then go up 5lbs, recheck, adjust as needed, then go 5pi more. Keep going til either your out of injector, turbo, or pump. Once your psi is maxed, you can play with timing and boost to find a compromise for best power. Sometimes less boost with more timing makes for better power, sometimes more boost and less timing makes more. There are a lot of variables and every engine responds different.

Generally with pump gas, you use boost to add power rather than aggressive timing. On race fuels/e85 you can max out timing for more power, plus lean it out more for better lean torque.

Please correct me if I'm wrong. I'm not a pro tuner, just a simple street tuner with limited experience tuning.
 

diambo4life

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Edmond, Oklahoma
Different ways to skin the cat...really. I personally shoot for a target AFR first. Once I get that dialed in...I turn the boost up to a certain level to achieve the airflow I need...then start adding timing to it until I establish the knock threshold for that particular setup. At this point I can either back off the timing a little and add more boost or reduce the boost and add timing. Of course...going with whichever nets me more power while keeping knock away. This is just what I do. Of course on stock stuff....being less aggressive with timing and running more boost usually is the safer route in most applications.
 
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ghostinthevr4

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Jun 11, 2008
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587
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Fresno, Califonia
Quoting prove_it:
But for how long?



A long time if you know what your doing and yes I'm talking about stock head bolts and composite gasket. I got a friend who found a low mileage block put a massive Borg Warner turbo on it added nitrous ran 10 sec quarter miles and raced it almost every weekend for money and street tunes his own sh*t.

It will last for a while if you play your cards right.

Sorry it wasn't on pump gas though E-85 and a auto.
 
Last edited:

92_talon_awd

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Knoxville, TN
Quoting prove_it:
But for how long?


In my case, felpro gasket with ARP's lasted about 3.5 to 4 years hitting 30psi at least 4-5 times a day. Plus some good rally-x
 

MX4

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Apr 9, 2001
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780
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New Zealand
Thanks for the info everyone. The car is in the workshop now but wont be getting tuned until mid november (unless there is a cancellation). The tuner will phone before the car goes on the dyno to see what the RPM/boost limits are that I want him to work to. Will post the results as soon as I have them
 

prove_it

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Sioux Falls, SD
Quoting 92_talon_awd:
Quoting prove_it:
But for how long?


In my case, felpro gasket with ARP's lasted about 3.5 to 4 years hitting 30psi at least 4-5 times a day. Plus some good rally-x



Fel-pro composite or MLS? The orginal quote was for a stock composite and stock head bolts. Of course a MLS and Arps will take that abuse.
 
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