Dyno Questions - Too Rich N/A?

GT2000JAY · Feb 29, 2004

I was wondering if anyone could help me with a little advice? I put the car on the dyno yesterday w/ wideband to make sure the fuel system was dialed in and I'm a little disappointed with the HP/TQ numbers - 239.1/275. I have to figure something is possibly "off" somewhere - others with similar mods are showing 15-20 more RWHP/RQTQ.

Does anyone have any idea what I'm giving up with my A/F on a naturally aspirated motor? I've read every thread I could search and seen information from anything in the low 12's is "pig rich" to 13 is too lean. I realize each car reacts differently, just trying to get an idea of where it should be to operate most efficiently and remain safe.

Anyway, here is the A/F graph (moved to .xls to calculate a "moving average". Interestingly enough, when the air/fuel dropped to 12.1:1 at 4000 RPM the TQ DROPPED 1.7 ft/lbs (from 273.5 to 271.8 - then rebounded at 4100 RPM to 275.1 when the a/f jumped up to 12.4:1.

So, how much am I leaving on the table with this A/F????

Thanks guys!

THE BLUE LINE IS THE A/F - THE ORANGE LINE IS A MOVING AVERAGE

2002BLGT · Feb 29, 2004

I would say its pretty flat considering some I have seen , I dont know if you would see any real gains by changing anything , every car is not the same , I would put some long tubes on it and you should see atleast another 20 rwhp

XStanger · Feb 29, 2004

I dyno'd at 229hp 270tq with just a High Flow H-Pipe and K&N. My A/F was actually in the 11's and that was pig rich!!

Ryan L · Feb 29, 2004

What's with the 30# injectors? You can use the 19#ers for another 75 HP. BTW, getting long tubes will not give you 20rwhp. Since you already have shorties and a mid-pipe, the peak gains may not be measurable.

GT2000JAY · Feb 29, 2004

The injectors were simply done out of opportunity and preparation. It was a bit of a pita to get everything set up correctly, but the car runs perfectly fine with them. They'll support whatever direction I choose to go next. I have a set of VT cams that will be in shortly and, honestly, I figured I'd be closer to 270-280 RWHP with the cams considering everything I've done.

After that is a blower - the injectors will be good to around 400 RWHP, so I have the fuel system covered and capable of handling most anything I throw at it. Just trying to figure out where I might be sacrificing some power. 239.1/275 seems low considering what I've done.

I agree with you on the l/t's. Yes, to go back and do it over again, l/t's may have been the way to go, but imo it's not worthwhile to change to l/t's and either chop/bend the midpipe or replace it.

Jay

daver01 · Feb 29, 2004

what kind of dyno was it done on?

GT2000JAY · Feb 29, 2004

It was on a dynojet - I've had the car on an MD in the past - this was a dyno day nearby. So, I can't rationalize the numbers based on the "MD reads lower" school of thought (which they do).

Which brings me to another point - before the headers, upper intake and MAF I pulled 218 on an MD - odd to me that I would only pull 20 additional horses on a dynojet with more modifications. Somethings going on, just gotta figure it out...

Jay

TacBear · Feb 29, 2004

GT2000JAY said:
It was on a dynojet - I've had the car on an MD in the past - this was a dyno day nearby. So, I can't rationalize the numbers based on the "MD reads lower" school of thought (which they do).

Which brings me to another point - before the headers, upper intake and MAF I pulled 218 on an MD - odd to me that I would only pull 20 additional horses on a dynojet with more modifications. Somethings going on, just gotta figure it out...

Jay

Every car is different, I was disapointed with my Dyno yesterday:

241 rwhp
290 rwtq
with the mods below.

GT2000JAY · Feb 29, 2004

TacBear said:
Every car is different, I was disapointed with my Dyno yesterday:

241 rwhp
290 rwtq
with the mods below.

TacBear,

You're absolutely right - they are all different, but dayum... I was still hoping for a little more - well, if she won't take it herself guess I'll just have to force feed her.

I am going to have them bump the timing a little and take a small amount of fuel out just to see what happens.

TacBear · Feb 29, 2004

GT2000JAY said:
TacBear,

You're absolutely right - they are all different, but dayum... I was still hoping for a little more - well, if she won't take it herself guess I'll just have to force feed her.

I am going to have them bump the timing a little and take a small amount of fuel out just to see what happens.

I'm having a delema just like you. One way or another mine will be 300 rwhp or more by the end of the year. either by P & P heads,cams and headers,Nitrous or SC!

Dyno Questions - Too Rich N/A?

GT2000JAY

2002BLGT

Well-Known Member

XStanger

Ryan L

GT2000JAY

daver01

GT2000JAY

TacBear

GT2000JAY

TacBear

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