I finally got my car tuned and i made 260rwhp at 11psi. I was hoping to get a lot more power but my car was leaning out on the stock injectors so the tuner didnt want to raise the boost. im just curious how some people get away with running higher boost (13-14psi) without leaning out on stock injectors.

MODS:
PFC
streetport
poormans Non sequential
rewired supra tt fuel pump
v-mount
3" highflow cat
3" DP/CB

 

There is something wrong with your car or the tune. We have tuned cars with less mods then yours, that still have the factory smog equipment, no porting, stock injectors, etc to right around 300whp@12psi.

If you were going lean then add more fuel in those cells. If it was maxing out the injector duty cycle at such low boost and hp then there is probably an issue with the fuel pressure.

 

Original Injectors? Mileage? Also, what about the fuel filter when was it last changed? Just a few basic questions that could be at the source.

 

my car is similar to yours. i ran out of stock injector at 240whp and then i had 550/1300's and ran out at 330whp. not all rx-7s are the same on how they flow fuel. i have another rx that runs 550/1300 and makes 380whp with more injector to go. since you already have the pfc i would go right for the 1600's you will be happy.

on the power concern....

bring it to the drag strip and post up your trap speed. dyno's are the most inconsistant way of indicating power. they are just a tuning tool. our local dyno's here read extremely low even the dynojets. i made 450whp when i went 132mph through the trap. there is also another member making 340whp going 123mph. which does not match up for power to speed.

 

Definately seems pretty low hp numbers though, even if dyno's are innacurate. I made 275 stock ports, 10psi, automatic, downpipe midpipe and catback, and intake. Was not leaning out at all.

 

brand new fuel filter, turbo and engine rebuilt 30k miles ago, and stock injectors.

the tuner said he has highest afr at 11.9, so i guess it is my streetport, i was afraid that it was something in my fuel system. id like to hear more from people with same mods and dyno #'s.

thanks to everyones responses.

 

Your streetport is not causing you to run out of available injector at such low boost and power. If anything you should have had higher then normal power at lower boost. You are making less power then a stock ported engine with similar mods as you. You do have a problem with your fuel system or the tuning, like I said before. My guess is that the fuel pressure is dropping off, for one reason or another, possibly a faulty o-ring at the pump allowing fuel to blow by.

Another example we have a customer with stock ports, full exhaust, stock twins, SMIC, stock injectors 326rwhp @ 13psi. All of our dyno tuning is done on a Mustang Dyno, which is "supposed" to read less than a Dynojet

With your current power reading, even if you were to upgrade your fuel injectors, and up your boost to 14 you would only be at 290ish hp, very low. To put this is perspective we have a different customer with the same mods as you, NS twins, streetport, FMIC, w/ 1600cc secondaries that is at 359rwhp at 15.7psi.

 

What was the duty cycle of the injectors? Not that you should do it but I went 100% duty on my twins and that was @15psi.

Had I stayed in a safe range I suppose I could have maxed them out much earlier. Don't get focussed on the dyno number. Each machine is different and the end number they produce can be wildly different.

 

JDM: Who tuned it? I'm curious.

 

nelson @ rotary racing reliability.

when i installed the supra fuel pump i reused the oring and spacer. i might have to recheck the fuel pump.

 

i was wondering the same thing. what is it roughly best to tune for 85% duty cycle at most? or did u really max 100% out? ive ran mine to 95ish, but not on a dyno lol

 

I made 286whp @ 15 psi on the stock motor, twins, and IC. On the 4x850 setup, I don't remember the duty exceeding 80% and my tune was fairly rich. The stock injectors might have been able to hack it, but I would be hitting near 100%. The stock SMIC was a huge bottleneck as I found out later when I upgraded it.

 

first time i got tuned. stock i/c stock injectors stock ports, full exhaust , no smog... i made about 276 at 90%inj duty... at 11-12 psi

after some other mods, aka whats in my sig, i just made 380hp with 1300s and seq turbos at 90%.. i really wish i got 1600s instead so i could of break to 400.

 

I went completely 100%. I only did it two runs on the dyno, then I upgraded the fuel system.

 

i didnt get a dyno sheet so im not sure of any numbers right now other than what they told me. ill go back today and try to get a print out.

thanks everyone for the input.

 

Mods:
Stock Ports
Precision 60-1 with .96 hotside @ 15psi
550cc primaries/1600cc secondaries
HKS Ignition Amplifier
Nippondenso/Supra TT Fuel pump
Apexi PowerFC/AVCR Boost Controller
Koyo N-Flow radiator
Greddy FMIC

I made 309 whp and 263 torque

 

do a pressure test on the pump to the fuel rails, it should be static around 90 PSI or so, leave the pressure tester on and unclamp the return line and see if the pressure regulator is raising pressure normally under boost.

the fuel filter is one of the most neglected tune up items on an FD because of it's screwed up location.

 

The OP has provided zero information on the dyno itself or the dyno conditions.

 

Ignoring the dyno numbers since those are meaningless, that sounds about right in my experience. With a street port and stock injectors you start running out of fuel around 11 PSi. It varies from car to car depending on size of street port, fuel pump setup, and injector health but around 11 PSi is the average. On stock ports, you can run up to 14-16 PSi (varies from car to car) on stock injectors but not with a healthy street port. Your tuner was wise to not up the boost anymore.

Upgrade your fuel system and then go get it tuned again.

thewird

 

I have 4x 850 CC injectors in a milled rail with A/N fittings for sale.

 

Good luck passing CA smog with 850 primaries...

 

Oh, how I am so happy to live in BC. Aircare here is a joke.

 

Completely possible with an worthwhile standalone.

 

I went to the tuner today and they told me that my tune is conservative and safe. there is nothing wrong with my fuel system, its just time for some upgraded secondaries or like some of you dual pair of 850's. like the wird said my streetport has made a difference on the tune. thanks everyone for the responses.

this is what they gave me, they used an external A/F gauge so i was not given any of those #'s


RunFile_001.drf: 75.35∞F 30.15in-Hg Humidity:16% STD:1.00 Average Gear Ratio:57.08

s RPM x1000 hp ft-lbs
0.14 3.00 N/A N/A
6.90 4.50 175.56 204.90
7.13 4.60 183.10 209.05
7.34 4.70 190.40 212.76
7.55 4.80 197.84 216.48
7.76 4.90 200.77 215.20
7.99 5.00 206.16 216.55
8.19 5.10 212.64 218.99
8.41 5.20 214.97 217.13
8.62 5.30 218.74 216.77
8.85 5.40 222.72 216.62
9.06 5.50 226.32 216.12
9.29 5.60 230.34 216.03
9.49 5.70 233.10 214.78
9.72 5.80 235.45 213.21
9.94 5.90 240.63 214.21
10.17 6.00 242.24 212.05
10.39 6.10 245.18 211.10
10.62 6.20 249.71 211.53
10.85 6.30 250.28 208.66
11.08 6.40 254.53 208.88
11.31 6.50 258.67 209.01
11.55 6.60 258.93 206.05
11.79 6.70 260.01 203.82
12.03 6.80 258.32 199.52
12.28 6.90 256.10 194.94
12.57 7.00 247.35 185.59
12.85 7.10 243.50 180.12
13.13 7.20 243.49 177.62
13.43 7.30 242.50 174.48
13.72 7.40 239.74 170.16
14.03 7.50 238.95 167.33
14.33 7.60 238.53 164.84
14.64 7.70 237.08 161.71
14.97 7.80 234.80 158.10
--------- --------- --------- ---------
MAX: 14.97 7.80 260.01 218.99
MIN: 0.14 3.00 175.56 158.10

 

Injectors are part of the fuel system

thewird