Stepped up the N2O/ car slowed down

[Redrooster]

I stepped up the gas on my 93 coupe from a 125 shot to a 150 and the car slowed down. I'm trying to get some ideas. The car should be running like a raped ape. Its stock other than gears/ lts/ electric fan/ cai/ 255 lph pump/Upr uppers and lowers.

The car ran a 12.75 @ 109 on 93 octane w/ the timing at 8 degrees.

I upped the jets to 150, added an aeromotive adjustable fuel pressure regulator, put some 112 octane fuel in, and turned the timing up to 14. This thing should be stupid fast. It slowed to a 13.1 @ 107.

The only thing i can think of is I had too much octane slowing the burn too much. A few days prior i had mostly pump gas in it and ran the car on the street and it felt like a monster. Just judging by the seat of my pants i would have guessed the car was going to run low 12s @ 112-114.

Before i get flamed i had a tuner helping with the car. We put in a new set of plugs and checked them immediately after spraying the car on the street. They looked fine.

Anyone got any ideas other than too much octane?

 

[Swarzkopf]

I think you need to monitor the air/fuel ratio on a wideband...the plugs only tell you if your in the "safe" zone, not the "maximum power" zone.

You could be either way too rich or slightly lean. The 112 octane is probably too much (I do assume you don't have cats too).

 

[Redrooster]

No cats, bbk lts, off-road x w/ Mac cat-back.

 

[jjd975]

I would try it with 93 octane and 6-8* timing and go from there.

I ran a 150 shot many times on pump gas w/o issues.

As for the test run on the street. Did you shut the motor down as soon as you finished spraying the car or did you continue to drive it? If you drove it some and then pulled the plugs you didnt get good info. Same thing at the track. You need to shut it down after the traps, not drive it back to the pits.

 

[Redrooster]

No I probably went maybe 1/2 mile after the run through the gears on the gas.

What gets me is, I basically ran the thing on pump gas at 14 degrees timing and it ran fine. i just put the 112 in there thinking it would be added insurance.

 

[86bluecobra]

i bet you are running 2 rich now. the other thing is perhaps you lost a little time over traction? what were your 60 foot times for the 2 runs? perhaps you are losing a little time there.

 

[1SLO306]

yup u need to find out what the air/fuel ratio is on ur car.

buddy has his 02 WS6 tuned for 13.0 A/f and when he sprays its 14.5 a/f he is getting it tuned for the 125 shot soon.

 

[Speeds8erM-1]

Nitrous hates timing! That and adding all that octane probably didnt help. You should try the timing backed off again and see if it picks up anything, then play with the octane if it is safe. Get it on a dyno with a wideband or buy a wideband for the car!

 

[Redrooster]

i bet you are running 2 rich now. the other thing is perhaps you lost a little time over traction? what were your 60 foot times for the 2 runs? perhaps you are losing a little time there.

Yeah, i lost a little time on the 60'. I couldn't get it to 60' better than a 1.94. I ran a 1.85 before, but that still doesn't account for the mph lost. I would have been okay with running a 13.1 at 112. I could have blamed it on the tires.

 

[86bluecobra]

i was re reading your post and i agree that it is your timing that is hurting you. when you add more juice you need to back off the timing. since you were adding another 25 hp shot back timing to 7. or leave at 8 degrees. try it there also don't run that gas go back to 94 octane fuel. thats what i run aswell. this should get you quicker. i believe 13 hp is good for 1 more tenth in the 1/4 so adding that N2O may get you closer to 12.5's. but don't expect 11's.

 

[mustangsally93]

Nitrous hates timing! That and adding all that octane probably didnt help. You should try the timing backed off again and see if it picks up anything, then play with the octane if it is safe. Get it on a dyno with a wideband or buy a wideband for the car!

thats what eat my rings in my pony with 30k miles. Retard the timing!!! This time I got a msd for my SH$&@$&(@(*&$@*$&)@$&@)*$&@)*$&@)@)$)$*(@)$)$$)*$)*$)*$)*$$$*)*%&)*(#_#*%$&)*%&)$7%@)IT

 

[Redrooster]

Why would you say nitrous hates timing? Assuming there is no detonation it should make more power with more timing to an extent.

 

[stang8urimport]

Why would you say nitrous hates timing? Assuming there is no detonation it should make more power with more timing to an extent.

I agree 100%... Timing will be based on how much fuel/octane you have. If you run a 150 shot with pump gas, your timing will HAVE TO BE lower then if youre running 150 on 112 octane. The octane helps prevent detonation, and allows more timing. But, the only way you'll know what the timing should be is by getting a wideband, or getting it on the dyno would be the best idea.

 

[mustangsally93]

it like every 25 psi of nitrous you need to retard the timing like 1 or 5. When I had my motor rebuild they were telling me about it. Thats why I'm going to a msd with nitrous controls.

 

[bluevenom867]

Nitrous increases the burn rate,the key is optimizing the timing,a/f ratio,and plug heat range.The higher octane fuel you were runing probably had an increase specfic gravity,witch means its heavier and there for doesnt need as large a jet (or for EFI as long of an injector pulse).

Also,general rule,retard you timing 2* per 50hp sprayed.

Btw,was that leaded fuel?

 

[86bluecobra]

surprised it took you so long to chime in venom.

 

[bluevenom867]

surprised it took you so long to chime in venom.

Lol,yea sorry bout that I was looking around in talk a litle too much lately...

 

[86bluecobra]

so iff you ran 114 octane odds are you wouldn't need the reccomended fuel jet on the 150 hp shot? it would be over kill and making the car run very rich?

 

[bluevenom867]

so iff you ran 114 octane odds are you wouldn't need the reccomended fuel jet on the 150 hp shot? it would be over kill and making the car run very rich?

Depends,figuer out what the specific gravity of the fuel is you want to use.

For every .01 increase in spec. gravity,decrease jet size by 1,and vice-versa for less spec. gravity.

Oh,and pump is normally .74ish area spec. gravity.

Edit:I was talking about carb jets,nitrous fuel jets will probably be the same,just lower the pressure.Oh,and if your runing the NOS recogmended fuel jet,then most likely your runing rich as it is...lol.Always play with the pressure first,and if you cant get it leaned out enough,then reset the pressure (back to 7-7.5psi or whatever your "base" pressure was) and go down two jet sized for the fuel solinoid (i.e. If you had a .048 @ 6psi go up to 7psi and drop down to a .046 jet,then lower your pressure till its right).

 

[Daggar]

...and just for "gee-Wiz"... a higher octane does not "slow" the burn rate. I'm not sure where this particular myth comes from. Octane rating describes the fuels resistance to detonation and has nothing to do with it's flashpoint or quickly it burns.

Something else worthy of note: Race fuel is not the same as pump gas. If you run race fuel then you need to tune for race fuel. Switching back and forth between the two without the necessary modification will kill performance. Thinking that the only difference between pump gas and race fuel is its octane rating is also a huge mistake.