just got back from the dyno.car was not making as much power as before running too rich. what can i do to lean out the car? i am running my vec at -20high and 0 low. when i dynoed 4 months ago it ran perfect with the settings at -20 and +6 but cant figure out why it is suddenly running rich. did get 593rwhp @5100 rpm and 746rwtq @3400 rpm. my torque numbers seem low compared to others squeezin the bottle. and hp is low also.
dyno running too rich
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Doug Supercharged Vipers
Enthusiast
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by trent:
did get 593rwhp @5100 rpm and 746rwtq @3400 rpm. my torque numbers seem low compared to others squeezin the bottle. and hp is low also.
<HR></BLOCKQUOTE>Some people would kill to have your problems
.
Those are great numbers. Without knowing the specifics it's very hard to compare before and after dyno numbers spread over a variation of time, especially when using nitrous. Too many factors to consider i.e. weather conditions, bottle pressure etc... In the world of nitrous; pressure is power (of course within certain limits). And running on the rich side is better than running on the lean.
Good numbers,
Doug
did get 593rwhp @5100 rpm and 746rwtq @3400 rpm. my torque numbers seem low compared to others squeezin the bottle. and hp is low also.
<HR></BLOCKQUOTE>Some people would kill to have your problems
Those are great numbers. Without knowing the specifics it's very hard to compare before and after dyno numbers spread over a variation of time, especially when using nitrous. Too many factors to consider i.e. weather conditions, bottle pressure etc... In the world of nitrous; pressure is power (of course within certain limits). And running on the rich side is better than running on the lean.
Good numbers,
Doug
Tom Welch
Enthusiast
How do you know its too rich? You must dyno at a dynojet facility with a wide band 02. Anything else is wasting time and money.
The VEC-1 needs to be disconnected. The air fuel meter can stay on but the unit takes too long to reprogram the computer after settings are changed and you may end up damaging something. It takes several key-strokes to see a change made on the vec-1 even though you may hear and feel that the motor is running different. I have spent dozens of dyno runs testing this device as a means to retard the timing for nitrous. Problem is that you can't just reset the dials and get an instant change in actual settings, we saw that it took several start and shut off sequences before changes in a/f were noted. This is not acceptable for adjusting "on the fly" to use nitrous. This is not to take anything away from this device, its just not perfect for this situation.
You are correct, your numbers are down from most, but not bad. The average NGP system on a car with good headers and exhaust will make about 640 RWHP @ 800+ RWTQ. Its not the system, it is simple jetting and liquids under pressure. You have other issues. You mentioned on another thread about a backfire and changing plugs. I suggest some more investigation into these things.
On a final note, are you using stock gears? Higher numerical gears have been known to skew dyno numbers down a bit. Please feel free to email me anytime with questions.
Tom
------------------ Http://btrviper.com
352-690-9600
1997 GTS, BTR 750 SS
9.92 @ 143 MPH
776 RWHP @ 954 RWTQ
All for less than $ 20K Installed
<FONT COLOR="#ff0000" SIZE="1" FACE="Verdana, Arial">This message has been edited by Tom Welch on 12-05-2002 at 07:40 PM</font>
The VEC-1 needs to be disconnected. The air fuel meter can stay on but the unit takes too long to reprogram the computer after settings are changed and you may end up damaging something. It takes several key-strokes to see a change made on the vec-1 even though you may hear and feel that the motor is running different. I have spent dozens of dyno runs testing this device as a means to retard the timing for nitrous. Problem is that you can't just reset the dials and get an instant change in actual settings, we saw that it took several start and shut off sequences before changes in a/f were noted. This is not acceptable for adjusting "on the fly" to use nitrous. This is not to take anything away from this device, its just not perfect for this situation.
You are correct, your numbers are down from most, but not bad. The average NGP system on a car with good headers and exhaust will make about 640 RWHP @ 800+ RWTQ. Its not the system, it is simple jetting and liquids under pressure. You have other issues. You mentioned on another thread about a backfire and changing plugs. I suggest some more investigation into these things.
On a final note, are you using stock gears? Higher numerical gears have been known to skew dyno numbers down a bit. Please feel free to email me anytime with questions.
Tom
------------------ Http://btrviper.com
352-690-9600
1997 GTS, BTR 750 SS
9.92 @ 143 MPH
776 RWHP @ 954 RWTQ
All for less than $ 20K Installed
<FONT COLOR="#ff0000" SIZE="1" FACE="Verdana, Arial">This message has been edited by Tom Welch on 12-05-2002 at 07:40 PM</font>
Tom Welch
Enthusiast
Trent,
I just took a look at the record keeper database on this site and even though your numbers are a little off, your car is amoung the top 15 cars with regards to HP and TQ. Lots of folks have not entered their numbers yet, but its a decent place to compare what you have done for mods, and how much you spent in comparison to everyone else. All you need is a bit of tweeking, and to make sure that you have no internal issues with that backfiring that you claimed earlier.
Best of luck,
Tom
I just took a look at the record keeper database on this site and even though your numbers are a little off, your car is amoung the top 15 cars with regards to HP and TQ. Lots of folks have not entered their numbers yet, but its a decent place to compare what you have done for mods, and how much you spent in comparison to everyone else. All you need is a bit of tweeking, and to make sure that you have no internal issues with that backfiring that you claimed earlier.
Best of luck,
Tom
Take a previous pull and graph it alongside one of the recent pulls and post it. Make sure you include the a/f's with the power/torque reading. Without seeing the two juxtaposed everyone is guessing.
Stating a peak rating is not the whole story you can have similar peaks and have huge differences in the area under the curve. If you can post the two, also include the jet sizes and the temperature.
Stating a peak rating is not the whole story you can have similar peaks and have huge differences in the area under the curve. If you can post the two, also include the jet sizes and the temperature.
did hook up to a/f wideband. car was running 10/1 or under and lean at low throttle but kept fluctuating. i did have the check engine light on a week ago and had it reset. then drove the car about 150 miles before i dynoed the car. the stock plugs are back on gapped at 34 (thought it may have been the ngkfr5-1 that was causing my backfire). checked the wires to make sure they were secure and also made sure the exhaust was secure today and they were. only thing that i can think of is maybe my vec bit the dust or connection went bad. what else should i check? the gears are stock.
tom what internals could cause it backfiring and running rich?
tom what internals could cause it backfiring and running rich?
the car is running rich on motor only too. was down 20 hp on motor alone. 444 hp 4 months ago temp was over 100 degrees. yesterday dynoed 425 on motor temp was 58 degrees.
i am glad it is running richer than leaner but too rich i would guess is not good either.
i am glad it is running richer than leaner but too rich i would guess is not good either.
don't have a printout of the a/f but only the hp/tq graph.
got the back fire problem fixed by disconnecting the pcm for 10 minutes and it seems to have reset everything.
went to the track saturday and ran 11.22 @126.4 mph. lost .2 seconds compared to last time at the track when i ran [email protected]. i think it was a little cooler saturday then the previous time. i have my n20 system 10 jet sizes higher than my previous run but am losing time and mph.
got the back fire problem fixed by disconnecting the pcm for 10 minutes and it seems to have reset everything.
went to the track saturday and ran 11.22 @126.4 mph. lost .2 seconds compared to last time at the track when i ran [email protected]. i think it was a little cooler saturday then the previous time. i have my n20 system 10 jet sizes higher than my previous run but am losing time and mph.
phiebert
Enthusiast
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Tom Welch:
On a final note, are you using stock gears? Higher numerical gears have been known to skew dyno numbers down a bit.
Tom
<HR></BLOCKQUOTE>
Tom, I swapped to 3.55 gears and had a lower HP than I had previously. But everyone I've ever talked to says that gear changes won't make difference on a dyno. My theory though is that if you are supposed to be in 4th gear for a 1:1 ratio and you change the rear end, you aren't really at 1:1 in motor to back wheels anymore are you?
On a final note, are you using stock gears? Higher numerical gears have been known to skew dyno numbers down a bit.
Tom
<HR></BLOCKQUOTE>
Tom, I swapped to 3.55 gears and had a lower HP than I had previously. But everyone I've ever talked to says that gear changes won't make difference on a dyno. My theory though is that if you are supposed to be in 4th gear for a 1:1 ratio and you change the rear end, you aren't really at 1:1 in motor to back wheels anymore are you?
jack the temp before was 88.7 and the last time it was 68.6 degrees. the propane was at 160psi and nitrous at 950. i cured the backfire problem by unplugging ecu. but now when i try to adjust the vec settings it starts backfiring again so i have to keep resetting the ecu. now that i have no backfire issues(with the vec set at zero) im gonna go to a better dyno shop. tom gave me a few tips on different jetting so i'll try that also.
Re: propane pressure
Were you using a bottle heater on the propane also?I only show 109psi (@70 deg) which is what the fill specs say on the bottle...will that be way to lean?Should I not use the nitrous heater without a propane heater also?thanks!
Were you using a bottle heater on the propane also?I only show 109psi (@70 deg) which is what the fill specs say on the bottle...will that be way to lean?Should I not use the nitrous heater without a propane heater also?thanks!
Re: propane pressure
MW:
Excellent observation, propane has many merits, however, it has to be kept warm or you will start to run lean, however, that seems to be the opposite of what is happening.
On a nitrous car I do not understand the need to use the VEC1. I had the same experience that Tom had. The VEC1 simultaneously controls both timing and fuel, thus, limiting what can be done. Air/fuel ratio is easily controlled by proper jetting. Why would you want to throw in another variable when you can achieve the proper a/f with a simple/fixed repeatable process.
Look in any serious nitrous book and everyone will strongly emphasize that tuning should only be done with steps that are instantly repeatable. As an example it is not a good idea to use a single bottle for a two stage system, because, the pressure is a variable at the time the second stage comes in.
I found that I had to use a bottle heater to get consistency out of the propane. The problem is exacerbated on the Gen1's since their injectors can't flow as much fuel as the Gen2's. You don't want to run when the propane is at 120 psi. The pressure drop and resultant temperature change across the bottle valve will drop the pressure even further causing a lean condition. I have charted the pressure drop in the propane delivery system and 120psi does not flow enough fuel.
MW:
Excellent observation, propane has many merits, however, it has to be kept warm or you will start to run lean, however, that seems to be the opposite of what is happening.
On a nitrous car I do not understand the need to use the VEC1. I had the same experience that Tom had. The VEC1 simultaneously controls both timing and fuel, thus, limiting what can be done. Air/fuel ratio is easily controlled by proper jetting. Why would you want to throw in another variable when you can achieve the proper a/f with a simple/fixed repeatable process.
Look in any serious nitrous book and everyone will strongly emphasize that tuning should only be done with steps that are instantly repeatable. As an example it is not a good idea to use a single bottle for a two stage system, because, the pressure is a variable at the time the second stage comes in.
I found that I had to use a bottle heater to get consistency out of the propane. The problem is exacerbated on the Gen1's since their injectors can't flow as much fuel as the Gen2's. You don't want to run when the propane is at 120 psi. The pressure drop and resultant temperature change across the bottle valve will drop the pressure even further causing a lean condition. I have charted the pressure drop in the propane delivery system and 120psi does not flow enough fuel.
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