I had a few questions about nitrous.

I have a 10.5:1 comp ratio. Is that safe for a 100-125 shot of nitrous?

I have 4 bolt main, hyperuetic pistons, cast iron vortec heads.

Is there anything that I have to worry about besides my compression ratio when spraying this much nitrous? Im talking as far as material tolerances. I know I would want a bigger fuel pump and such.

 

is this lt1/4 or l98 or other?
stock crank/ rods?

i mena stock lt1s have 10.4:1 i believe and lt4s have 10.5:1
i have a 125 shot on mine. and i have an all stock internal lt1.

the weak point is the hyper pistons those things have been known to shatter with too much tq aka cylinder pressure. but with a 100-125 shot it should be ok.

also u want a wet system. if your engine goes lean.... boom
ull have to get a heat range or 2 colder... u want short burn recessed electrode.
92 + octance is a must.

 

looks like he has an 86

 

Yes I have an 86. So that seems like a safe number? even with hyper pistons? the crank and the rods I would assume are no stronger than the original stock. i dont know what the guy put in this new engine as far as that part of the bottom end. So changing the plugs is the only other thing eh? how does your car feel with the 125 shot? do you have times?

Thanks for the info

 

i can tell you what uneed to know but ultimately u should a little shaky on the subject of nitrous oxide. so do alot more research and give it a month or 2.

changing the plugs is not the only thing

first you need to make sure the car is in good running order. compression test would be a good idea. but u said its a new engine.. still i dont trust ne one double check.

2nd u need to make sure the engine is tuned well... meaning there is no big loss of power and you have good AFR.
the goal AFR for n20 should be about 12.6:1
say you are running 14:1 at WOT w/o n20 youll need to go with more fuel with the wet system.

if you dont know anything about this and adjusting the AFR under WOT then have an installer do it.
id start with a 75 shot wont do you wrong. the first couple of months u wont believe the poiwer increase then u want more.. maybe go with a 100 shot that is once u find everything runs great with a 75 shot.

do you plan to install yourself?

if you do im sure we can help u step by step it via this forum... there are alot of guys here who can help... aka skateparkdave me etc...

awhile ago i bought a book or installing and tuning nitrous oxide systems and man did it help.
if you install yourself you need to know the system and all of its components and their functions to be able to install and diagnosis ne problems u may encounter.
there are alot of little things that u might miss that could cost you big.


as far as times idk i havent run my car yet. and i have an lt1
but it is said that for every 100 shot its about 1 second gained in 1/4.

later your friend
Sean

 

Thanks for the info Sean, I would defininatly like to know as much as I can before getting into n20. You are right I am still learning about it. I would like to install the system my self so I could be totally self reliable if somthing went wrong with it. Ill let you know when I get it, propblably not for about a year. Thats why im looking into it now. if you have any other info im all ears

 

search amazon.com and look for nitrous oxide books i got one.

also the lt1 has a 10.5:1 and lt4 has 10.8:1 sorry for any confusion.

 

I have an LT4 w/ 10.8CR. 100 shot is the limit without using any timing retard. I will be installing a kit myself shortly and even at only 100 shot I will be running a mix of 100/93 octane. Detonation is not your friend and he's not welcome in my car! 125 should be safe at your CR but I would highly suggest a timing retard. Good luck

 

Sean with 11 inch DR on the rear ,I run 315 nittos and a 125 shot your car at 2200 ft DA should run 11.21 at 123 mph.
That is if you shoot the nitrous after the 60' mark.I have never shot mine off the line.
I shot my L98 off the line with 150 shot lots and it only runs 11's at 117mph.
I would change the plugs in your L98 to a recessed electrode I forgot the one I used on my L98 .ON my LT1 I use the ngk B8EFS on my Lt1.
ON your L98 I did not run a retard box ,You can set your timing so I just disconected the EST set the timing 6 deg retard hooked up the EST and blew a 150 shot through it.
I wouldn't use more than a 100 shot on your L98 they peek in RPM to soon and the engine will not gain anymore power.

 

so a timing retard is in need eh? I could get one of those from msd right?

 

anything over a 75 shot and it is strongly recomended...
thats right l98s do thave the conventional distrib...

you did 6 degress retard... i always though for that power itd be more like 2-4 degrees. the nos book says 1-2 degrees retard 1-2 heat ranges colder and 92 plus octane

how far do you retard it with the lt1 and 150? 2 degrees

 

I would be concerned about the 10.5 scr and the cast iron heads with regard to detonation. This combo is not quite as forgiving as the L-98 or 113 heads when running higher compression and a decent shot of N2O.
Aaron

 

I have the wheel retard MSD on my LT1 ,they said it coulden't be done.I run about 6 degrees or 8.
The knock sensor module from the LT4 instead of the LT1 will handel the engine just fine.
Just don't use it off the line I blwe the motor mount and right front shock ,just turning it on just out of 1 st gear.

 

got ya.
yea i wouldnt spray off the line. for 2 reasons traction and driveline shock.
do you spray through shifts?
i dont unless its absolutely imparitive that i win.

i need to get a built 4l80e a nice bottom end and up the just to a 300 shot.. man $ $ $ ughh oh well..

my tuner just showed me how to retard timing with LT1 edit yesterday...
its retard vs airflow. and you do it like the mainly max airflow and 3000 rpm up. i need to play around with it. i guess itd be good for the track i could take my laptop and retard timing for the runs... but the MSD wheel retard its alot better and easier to do ... as you can switch in between. the maximizer 2 is pretty cool too as i was reading you can have it activate the a retard box if u program it in i cant wait to buy one of those things and play around with it. but thatll be awhile too



Sean

 

Before you go playing around with the computer in your car,make sure you run a floopy disc on the info you have in your computer now.
That when you screw up it can be returned to the original settings.
Just a word to the WISE!
I use my computer at the track all the time ,just set it up so when you launch ,you can hit the space bar to activate the computer.
I also use a hyper puke programmer,it is good for quick changes to the trans.
YOu should have one anyway ,GM was selling at gm dirrect at christmas time for $199.00.
A 4L80E if you want to cut up the tunnel in your car and pay $6100.00 for a trans I would get a real race car first.The 80's are only good up to about 1300 hp maybe 1500 if you bring the weight down on the car.
I have the same LT1 and auto as you,I shoot 100 shot once and a while 125 shot ,yes through the gears.
I bring back the timing as I go down the track from 8 degrees to about 4 degrees.

 

I do not believe you need to cut the tunnel to install the bigger trans.I seen a post or link on this board with good pics.and info on doing the swap

 

yea ive seen it too.
oh well..
i see bout that if i get to that.

 

I ran Nitrous on 3 different Lt1s. The first had 140,000 miles on it and was iron headed and I sprayed 150-175 for 1.5 years, with dragstrip duty every weekend. I never retarded the timing. This engine eventually lost a few ring lands and started smoking. The next engine was aluminum headed and I sprayed 150-175 and then sprayed 225. With the stock fuel pump, and NO timing retard, this engine blew to pieces on the 225. This information has been provided to let you know the high limit of N20 on stock stuff.

Peace

 

yea thats over the limit with out retard and 100 plus octane!

also what went in the engine? the pistons rods? caps?

 

Well... Truthfully N2O LOVES compression!! That's why we tend to build 14.00:1-plus motors for the bottle in competition. But, it's not really the compression you need to be concerned about on the L98's (and LT1's) that have stock bottom-ends. It's the weak-*** pistons. You can keep the damned thing out of detonation all you want and will still pop ring lands because of the excessive cylinder pressure; detonation isn't the ONLY thing that kills nitrous motors. Cylinder pressure on top of cast pistons with a short top ring land are not good partners; on a cast piston motor I wouldn't recommend more than a 150 shot and that's pushing it if you are spraying it REGULARLY. The cylinder pressure just beats the hell out of the piston. Most N2O mfg's have very conservative jetting in their kits and that's to alleviate instances of breakage; on a stock bottom end L98 or LT1 I wouldn't deviate much from the jettings (particularly the fuel side). Generally you can get away without pulling ANY timing up to 150 hp on a motor that can take it a little better but the mfg's rule of thumb is 2 degrees for every 50 hp... If you're going to run a 150 shot start out by pulling out six degrees...I like to use EGT's for tuning N2O and tune for a specific temp... I play with the timing until I'm very close and then I'll usually play with the fuel side to get it spot-on.
-Jeb