Ksths2

iTrader: (1)

I went to our local 1/8th mile track Friday night & decided to put 175 to my C5 Vette instead of my usual 150hp shot that works great in my car for many years. Car is a heads, cam, intake, blah blah blah etc setup.

Neal @ Nitrous Outlet gave me the jetting for it 73N/38F in my HSW 92mm plate. I took 4 deg out with my timing twister when N20 is on & i'm running BR7EF's gapped at .035 - I also run a N2O outlet progressive controller as well. I also had 5 gallons of 93 pump gas in it & 5 gallons of Sunoco 110 (leaded)

I had the programmer at 75% for 1.0 second then it dumps 100% - It ran great, pulled the wheels, 1.46 6.51 @ 106.2mph - I was super excited, no popping, surging etc, super clean pass.
I went right back up @ put the prog @ 100% right from the line & it ran 1.45 60' @ 6.49 @ 106.6mph. Outstanding!

I went back out later on that night, & it started popping on the big end when i clicked into 3rd gear so i lifted, came back around for my final round (no time to check plugs) & it started popping/breaking up/detonating as soon as the n2o kicked in so i lifted

I drove home, ran ok, pulled the plugs & they all looked really good but #7 had some peppering on the porcelin. Ground straps would good and sharp, couldn't tell where the timing mark was cuz i drove it home but I was going to put B8EFS in it and try it again but wanted to see what you guys thought first. & trying to figure out why it was perfect & then it started popping etc. Any suggestions?

Ksths2

iTrader: (1)

no help?

Chris, Neal, Fbodyjunkie, etc?

1) Bascially I need someone to confirm that putting in the B8EFS plugs are the right choice for my 175hp shot
2) Help tell me why all the other plugs look good except for #7
3) Why the popping or detonation on the hit now when the rest of the passes were super clean?

10secZ28

iTrader: (6)

1) a number 8 should be just fine for your setup
2) 7 will likely be one of your "hot" holes with that being said what color was the peppering?
3) I can't give you a clear answer.

plugs are unreadable once they have been driven on so you really have no data plug wise to work from.

Ksths2

iTrader: (1)

Yeah I thought #7 was always one of the hot holes, what other holes are hot ones? 6 & 8? I'm using a 92mm FAST intake.

Peppering was brown when i pulled this plug, I put a bright light on it & didn't see aluminum shinning back but I agree 100% that since I drove this back home this is now useless. Next time I'll make a run I'll log the A/F ratio & shut it off at WOT & check them again but i wanted to make sure I wasn't over looking something obvious.

Sofls1

iTrader: (16)

I run a very similar tune up with the 7 and have had success. The peppering your talking about is most likely detonation. I would pull at least another degree out.

Put some new plugs in it when you get to the track make a rip, then pull them out at the end. That will give you an idea of what you need to do from there.

You could run an 8 plug which may work better, but that is not going to be a substitute for pulling timing.

Also- as someone else said after you drive on that plug its basically unreadable for tuning purposes.

10secZ28

iTrader: (6)

we need to know more about the tuneup, what is your base timing on motor? what is it on the kit? The peppering sounds like fuel, you asked about other hot holes, 7 and 8 will usually be the hot one's due to a lack of cooling, but i believe Carter01 reported his #6 as the hottest. so get us some other info.

Ksths2

iTrader: (1)

to be 100% honest i'm not sure what the timing is on my engine. but i'm sure its aggressive. I had Jim at Speed inc do all the tuning & i'm taking -4 out with the MSD twister, N2o outlet said -6 - I don't have hp tuners to verify what any of my parameters are...... it is on my list of crap to buy though.

I went back and looked & 7 has very slight silverish hase/peppering on the radius's of the porcelin as well but all the other plugs look really good.
I agree w/ Sofls1 as well, I'll pull at least 1 more deg out total -5 maybe -6 like N20 outlet said pull the plugs at the end.

It just surprises me that it ran so good then all of the sudden started detonating like that, I would of thought that if it was a timing/fuel issue it would of done it from the start? BTW, the bottle pressure was a bit high on all these passes at 1150 at the beginning before I do my purge.

speedtigger

iTrader: (16)

The advise I was give by the nitrous guys on Yellow Bullet was to pull 6 to 8 for a 150 shot. They mostly said pull 8 to start.

10secZ28

iTrader: (6)

if your actually getting detonation 1 degree will not fix your issue, low timing will only hurt performance, too much will hurt parts, i like being on the other side of that line. If it were mine I would not be doing any more nitrous pulls until i know what was going on in my motor.

speedtigger

iTrader: (16)

Here is an interesting read on nitrous timing from one of the NOS experts.:
http://www.yellowbullet.com/forum/sh...is+-the+answer

Sofls1

iTrader: (16)

1. You need to drop that bottle pressure, that is too high. get it to the 950 range.

2. You need to find out what your base timing is. Call speed and ask him if he can tell you. He probably has a copy of your tune. I assure you that need to pull at least the 6 degrees like N2o outlet advised. I run almost the same tuneup and needed to pull more. (with straight vp 103 gas) If it were me I would pull 8, make a pass and tune your fuel first. Then once you get the fuel looking good try adding .5 deg, if it goes faster (which I doubt it will) and the plug looks good add another .5 deg

3. These changes need to be done on a fresh set of plugs and they need to be read right after the pass for you to be able to use them to make changes.

4. Read that link that someone posted by Monte Smith. That is the real deal there.

ATwelveSec02Z28

iTrader: (17)

It reads like you were hot-lapping the car.

Higher temps in the cylinder could easily lead to the popping you had. Also, Im assuming all passes were made on 1 bottle. Without a push system, once you go below 45% bottle capacity your bottle pressure fluctuation can lead to tuning issues.

There are a few ways to tune for the nitrous. Plug reading being a good way - like said, you need new plugs, tow to the line, once through the traps cut the engine, and tow back.

Just as an FYI - peppering on the porcelin would not indicate a major problem, just that your tune is slightly off. - Ive had damn near the entire ground strap burned off (Tried to run an 8 plug) and the car still ran without popping or surging. As for timing, Im running about a 225 shot and max timing is 17.5 degrees total, with a few more degrees pulled on a couple cylinders that tend to run hot. When I run one of my current tuneups in the car I dont even check the plugs anymore - I tune the timing using crank case vacuum.

Ksths2

iTrader: (1)

Motor is flawless, it'll run back to back 150hp shot all day long, i was just experimenting at the 175hp level cuz i run in a heads up street legal class, aka I needed to be faster.

I agree on the pressure & the -6 deg & the new plugs. That is first on the list to do

yes i was hot lapping the car, due to the way they run the eliminations for my class. You win the round, you come right back up & run again.
I run 2 bottles for that exact reason, recovery time between rounds & keeps steady bottle pressures, & i run 2 heaters.

Thats exactly how my 150 setup was, i had it down to where i didnt even need to check the plugs.

I'm planning on putting a new set of 7's back in it, run the old 150hp setup thats tried & true, if all goes well, put it back to the 175hp, with -6 degrees out, on a new set of B8EFS plugs, shut it down, tow it back & see what they look like.

Sound right?

ATwelveSec02Z28

iTrader: (17)

Just because something didnt happen with the 150 dont write it off as not an issue with more nitrous.

All of these things can effect the tune up. As said before too little timing (within some limits) hasnt hurt parts.... Too much will burn stuff up in a hurry. When I launch, Im leaving on 3.5º Total timing.... You wont hurt anything pulling a few extra degrees out.

Pull 8 or 10 degrees out at first, then work your way up til either the timing mark looks good, or you stop gaining ET. No need to put timing into it, just to get a timing mark on the strap if youre not gaining ET.

As for getting a good plug reading, Im not sure how youre set up at the track, but you need a fresh set of plugs - do not run the engine until youre ready for your burnout,.... once through the traps, turn engine off, and tow back to your pit

Ksths2

iTrader: (1)

k, sounds good, i'll let you know how it goes

Sales@Tick

iTrader: (3)

Fbodyjunkie here(I'm now Martin@Tick for those that didn't know)

These guys have you lined out.

I'd pull 7 and go from there on the B8EFS plugs and see what it does to the MPH.

Go from there. You have the timing twister and ability to change it on the fly use it.

Everyone has touched all the bases in here already no need for me to reiterate

BLWN1

iTrader: (6)

What are your mods?




http://www.yellowbullet.com/forum/sh...&postcount=270


from this thread
http://www.yellowbullet.com/forum/sh...489904&page=18

just curious about this?

Sales@Tick

iTrader: (3)

I don't think his problem stems from not a cold enough plug, but his problem stems from over advancing the ignition timing.

Usually I won't recommend sticking a colder plug in a different hole unless you've already tried pulling the timing back or tried other things to keep that hole happy. After you've tried those things and it still persists is a good time to then stick a colder plug in those holes.

Ksths2

iTrader: (1)

FYI, i sent Speed inc an email requesting my base timing info

Mods for engine are.
Still stock LS1 (stock bottom end) 50k miles
92mm FAST, 36lb injectors, ported LS2 TB, Speed inc rails
TEA 5.3 heads 2.02/1.55 stg II porting
SI6 cam 235/240 .643/.621 111+1 lsa
Flycut stock pistons
HSW 92mm perimeter N20 plate w/ Daves N20 outlet jetting & progressive controller

Neal@NitrousOutlet

Sorry we didnt get to you. Im passing it on to Dave so he can help you out. Feel free to call us as well if you need some help.