150 to 200 shot? .16 mph??
150 to 200 shot? .16 mph?? So with the setup in my sig right now I have trapped a best of 122.55 with a 150 shot of spray and this past weekend I changed to a 200 shot to get my 10 and my best MPH was 122.71 so going from a 150 to a 200 shot I only gained .16 MPH in similar air. With stock heads and cam motor can the motor just not ingest anymore nitrous than 150 shot and thats why I didn't gain anymore MPH? What do you guys think? Anybody else have a simiar experience with this?
So with the setup in my sig right now I have trapped a best of 122.55 with a 150 shot of spray and this past weekend I changed to a 200 shot to get my 10 and my best MPH was 122.71 so going from a 150 to a 200 shot I only gained .16 MPH in similar air. With stock heads and cam motor can the motor just not ingest anymore nitrous than 150 shot and thats why I didn't gain anymore MPH? What do you guys think? Anybody else have a simiar experience with this?
Yes weather conditions very close to the same. On the 200 shot I was pulling 6 degrees of timing and on the 150 shot pulling 4 degrees of timing with my interface unit. Yes bottle pressure the same also, 1000 psi.
Its a compucar kit so the jets for their kit are a 70 nitrous and 40 fuel and I called Compucar to verify that the solenoids would support a 200 shot and they said that they would but they could have been lying to me, who knows really.
Did check your plugs or data log any of those runs to see if you were pick up any knock retard? 6 degrees for a 200 shot isnt enough. Should be pulling around 8-10 degrees for a 200 shot.
Yes I datalogged and was only getting .4 degrees of KR and that was on the initial hit off the line and by the 60' is completely gone so there is a chance that its not even true KR. The general rule of thumb I have always heard is 2 degrees per 50 HP shot but from my findings that is very conservative. I have always started high like that pulling lots of timing then I start reducing it down a degree at a time watching my KR and I have found that 4 degrees works well at 150 shot and 6 degrees looked good for a 200 shot, however I did not gain any more MPH so thats the only thing that has me boggled. I am pretty famliar with nitrous as this is the third car I have had it on. At this point I am just curious if I have nitrous saturation of the motor or if with the 200 shot I am blowing through the converter a little bit causing me to lose the MPH I would have gained through the 200 shot. I have not pulled my plugs since this weekend when I sprayed the 200 but I have pulled them after the 150 shot only pulling 4 degrees and they looked great with no signs of any detonation.
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First, a .070 jet is not what I'd call a 200hp hit. It's closer to 160-170 at the tires. I'd like to see the plugs also, because I have a feeling it's got too much timing in it.
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Correct me if I am wrong but the knock sensor is there to detect knock or detonation so if I am not getting any knock or KR then how could it be too much timing? As I said this is not my first go around with nitrous, I have had it on 3 different vehicles pretty much setting it up the same way and I have never had a problem with burning plugs or melting pistons. The only difference this is my first time spraying a 200 shot, previously the highest was a 150 so as my original question stated has anyone ever had any experience going from a 150 shot to a 200 and what kind of MPH increase did you see doing it? I just want to see the average gain on a stock heads and cam LS1 going from a 150 shot to a 200 shot. Anybody?
I will pull the plugs over the next day or two and take pictures and post them up too see what you guys think. I don't think its a timing issue but I want to rule it out so its a good thing to do I guess.
Last edited by tording99Z28; Nov 9, 2010 at 05:39 PM.
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Knock sensors are not accurate enough to use to tune on motor, let alone on nitrous... you need to read the plugs after a run when the engine is shut down from WOT...
As far as MPH goes, stock bottom end, stock 853 heads, stock ls6 intake, stock injectors, stock maf, stock TB (homemade port job) and I went from 126 on a 150 shot to 131 on a 200 shot. It's not a saturation problem, it's a converter, timing or fueling issue. The plugs will divulge the truth, we need pics
Yes I datalogged and was only getting .4 degrees of KR and that was on the initial hit off the line and by the 60' is completely gone so there is a chance that its not even true KR. The general rule of thumb I have always heard is 2 degrees per 50 HP shot but from my findings that is very conservative. I have always started high like that pulling lots of timing then I start reducing it down a degree at a time watching my KR and I have found that 4 degrees works well at 150 shot and 6 degrees looked good for a 200 shot, however I did not gain any more MPH so thats the only thing that has me boggled. I am pretty famliar with nitrous as this is the third car I have had it on. At this point I am just curious if I have nitrous saturation of the motor or if with the 200 shot I am blowing through the converter a little bit causing me to lose the MPH I would have gained through the 200 shot. I have not pulled my plugs since this weekend when I sprayed the 200 but I have pulled them after the 150 shot only pulling 4 degrees and they looked great with no signs of any detonation.
One more thing, you're not just looking for detonation you are looking at your "fuel ring" (via cutting off the porcelain) and your "timing mark" (via reading the strap).
So then say you are getting 2 degrees of KR but you pull the plugs to check the "fuel ring" and the timing mark and the plugs look great, you should use the fact that the plugs look good over the fact tha the computer is detecting detonation? That kinda seems like trusting the butt dyno over a real dynometer to me. I am not disputing just asking, just seems bass ackwards to me.
I will pull 2 plugs on each side to start with and take some pictures of them and post.
I will pull 2 plugs on each side to start with and take some pictures of them and post.
So then say you are getting 2 degrees of KR but you pull the plugs to check the "fuel ring" and the timing mark and the plugs look great, you should use the fact that the plugs look good over the fact tha the computer is detecting detonation? That kinda seems like trusting the butt dyno over a real dynometer to me. I am not disputing just asking, just seems bass ackwards to me.
I will pull 2 plugs on each side to start with and take some pictures of them and post.
I will pull 2 plugs on each side to start with and take some pictures of them and post.
So the KR tool you are using is just that, a tool to get you close the answer you are looking for. Reading the plugs IS the ANSWER. And as far as your analogy goes with "trusting the butt dyno over a real dynometer to me" you have it backwards. The KR is the butt dyno in this case and the plugs is the real dynometer.
I see what you are saying about the WB being a tuning tool and gives you the A/F over the 8 cylinders and you wouldn't know which cylinder is the leanest until you pull the plugs. The computer doesn't average the knock over the 8 cylinders though and then give you KR, if it detects any knock on any cylinder it pulls pulls timing and reports KR so as I said I see what you are saying but it still seems that using KR would still be more beneficial than say using a WB.
I see what you are saying about the WB being a tuning tool and gives you the A/F over the 8 cylinders and you wouldn't know which cylinder is the leanest until you pull the plugs. The computer doesn't average the knock over the 8 cylinders though and then give you KR, if it detects any knock on any cylinder it pulls pulls timing and reports KR so as I said I see what you are saying but it still seems that using KR would still be more beneficial than say using a WB.
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what fuel was used on both settings?do a compression test or a leak down.what rpms are you shifting at ?check your valve spring pressure.what fuel pressure are you running?short shift with NOS!run a taller tire,and maybe you exhaust is restrictive.is your trans stock or upgraded?