jdawg04 4.8

iTrader: (1)

Hey guys/gals,

So i did some quick searching but didnt really find what I was looking for.

So the motor is a bolt on only LQ9 6.0 (mods in sig). I have the TrickPerformance P guage which is a progressive controller.

Im planning on throwing a cam in (TR220-224 or similiar) and have been toying with the idea of raising the CR by getting my heads off my 4.8 milled and worked or finding some 243s and going that route.

Now this is a daily driver and on Cali pump gas I would like this motor to last a bit if possible.

Besides the cam and the head work if I choose i dont plan on taking this truck much further if at all after the cam.

So i guess just let hear some of your opinions on what yall think or what you would do and also this is on a budget.

Nitro Dave's Nitrous Outlet

iTrader: (25)

I am confused to what you are asking? Are you asking if raising the compression is a good idea? What would the compression ratio be?

On another note..
Did they ever do the magazine article?
Dave

jdawg04 4.8

iTrader: (1)

Im asking at what point would the CR be too high for a relatively big shot 150+, i beleive using the 243 heads will put me around 11.0 iof not mistaken.

Also i plan on spraying atleast a 150 shot and will do more.

And about the article im sending you a PM after I post this.

Bullitt347

Compression is not the issue with nitrous. The type of fuel is the issue. If you are going to be using pump gas (92 octane) then your limit on how much nitrous used will be all in the ignition timing and how you can control taking the timing out. Nitrous makes the fuel burn extremely fast, kind of like hitting the oxygen lever on a cutting torch, so keeping the timing under control is the big issue. With over a 100 h.p. shot you should be looking at colder heat range plugs as well.

jdawg04 4.8

iTrader: (1)

i got colder plugs and im in California so we get the good stuff haha 91 octane.

So fuel and timing are the issue?

Sorry for the ignorance but im a nitrous newb sorta have had kits before but didnt know the why and how of stuff.

As long as i can keep control of my timing either thru tuning or a device that pulls timing on the fly when needed (if such a thing) or better fuel a CR of 11.5 is ok?

Bullitt347

Actually a compression ratio of 11.5:1 on pump (91) gas is a concern without the nitrous. It is very important that the engine be in excellent condition N/A before running nitrous. If the engine will not run on pump gas before nitrous, it will not run on pump gas with nitrous. I would guess that you would need a octane of 100 or better with 11.5:1 compression. Unless your talking about the LS7 engine which is 11:1 compression stock and runs on pump gas. The thing with compression is that you get the engine to run good with the compression you have. A 13.5:1 compression engine will run great on C-12 (112 octane) but you need to use C-16 fuel if your going to spray a 13.5:1 compression engine. C-16 was formulated for high compression Nitrous engines. (over 12.0:1) So when I said compression was not the issue, I was assuming that the engine ran the proper fuel for the compression you have BEFORE you use nitrous.

jdawg04 4.8

iTrader: (1)

i think im getting a better idea.

As long as everything is running very good N/A what ever the CR is and by what ever method your using to dial in a N/A after it good to go then thats when nitrous can be safe on a high CR motor.

So in other words if i decide to raise my CR i have to dial it in N/A and get it running by whatever method before adding the gas but adding the gas would be just like my truck now i dialed it in N/A then added the gas.

Am I even close or way off here? Thanks ahead of time

Bullitt347

Now you got it. Once you start spraying, say above 100 h.p then things like spark plugs, ignition timing and even fuel delivery come into play. Is the fuel pump your using big enough to handle the added demand of the nitrous ect.

jdawg04 4.8

iTrader: (1)

With the setup i have in sig (colder plugs as well) i have sprayed it with a 200 shot thbe tuner told me i was runnig rich. I actually have a walbro the shop ordered if i needed it

Now im not lookin to go crazy with it (may be too late) but im lookin at my next possible step other then cam.

Bullitt347

Running rich? How rich? What were the air/fuel #s? What did the plugs look like? Is it rich because the fuel jet is to big, or because you cannot light off the mixture? There are so many things to take into consideration to get it right.

jdawg04 4.8

iTrader: (1)

To be honest i couldnt tell you the A/F ratio i leave the work up to the guys at the shop i go to and they said pig rich.

What i do know is they spent most of the time dialing in the 150 shot and said id need more time tuning if i wanted to stay at 200.

98Z28CobraKiller

iTrader: (17)

Static compression is not so much the issue as the dynamic compression (determined by the cam). A high overlap cam will bleed off compression and still allow you to run pump gas. I have just a hair over 12:1 compression and run pump (93 oct in FL) without issue. As for nitrous, well the more you run, the more timing you have to pull out. I would think that once you are tuned for pump gas on whatever compression you end up with, you just pull another 4* or so for a 150 shot.