your opinion, will i hurt it?

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rustbucket · #1 Post by **rustbucket** » Wed Sep 20, 2006 10:53 pm

I just built a motor this year and want to run more nitrous, but im afaid im gonna screw up my motor. Im not sure how much is safe. Heres the set up:
406 cid 2bolt block with STOCK MAIN CAPS.
eagle 4340 crank
eagle hbeam rods
bottom end balanced
forged pistons (dome 12.8:1 comp.) with 64cc heads
patriot 225 aluminum heads 208/160
msd multi retard box.

Im trying to race the 6.0 class 1/8th and the car runs 6.90 on motor.
I have tried 275 jets on a bigshot plate and only ran a 6.60.
Most of my buddies are getting close to a second with that much juice.
Im still running a big 10 bolt rear end (456 gears) and a turbo 350 tranny. The car weighs about 3000 pounds.(72 nova)
I have been waiting on the tranny or rear end to go but Im mostly concerned about my new motor. The block is filled up to the lower water pump holes. Im not sure if I have supplied enough info to base your opinions but any would help me decide how much is safe.
thanks, tony

mytmouz · #2 Post by **mytmouz** » Thu Sep 21, 2006 1:12 am

You may need to tune your nitrous combo some more. I ran the same pretty much the same combo as yours except for the heads. It was consistently going from the 6.90's to 6.06. to 6.12 on a big shot kit with 175 jets depending on the air. It sounds like you had too much fuel. I'm sure someone else on here will have more info. Depending on the head gaskets you have, you should be good if you get the set up dialed in. Hope this helps.

#3 Post by **John_Heard** » Thu Sep 21, 2006 6:47 am

Sounds like your tune up is all messed up. That 275 shot should have been a lot more exciting than that. What jets, fuel pressure, timing, etc. are you using? Have you tried a smaller shot than the 275?

rustbucket · #4 Post by **rustbucket** » Thu Sep 21, 2006 11:32 am

I dont have the exact jet sizes with me but it was the jetts recommended in the big shot instructions. My fuel pressure is free flowing 5.25. I have tried 225 jetts but it really didnt make that much difference tahn the 275. I did however have low bottle pressure on the pass with a 6.60. I just bought a bottle heater. Maybe that will help.
Does my combo sound tough enough for a larger shot?

#5 Post by **John_Heard** » Thu Sep 21, 2006 12:54 pm

Don't start playing with a bigger shot till you get it to run right on what you're doing now. You are no where near the performance you should be getting out of a 275. In fact I think I would back it down to maybe a 200 shot, get it running good there then start back up. NOS jetting for the Big Shot is generally really fat and might be the reason for the poor increase. Start out with the recommended NOS jetting, timing, etc. then start pulling plugs and see what you have. More than likely you'll find that you'll need to square the jets up at 5.5 psi to get it to run. Low bottle pressure, depending how low might be part of the problem. Seriously I would back up to a 200 and get it running good there first.

ytnova · #6 Post by **ytnova** » Thu Sep 21, 2006 2:56 pm

What selenoids are you using also? Check the plunger on the nitrous selenoid, If they sit for a while or if it gets fuel contaminated the rubber tit on the plunger will swell impeding flow. Is it rolling black smoke or huffing on the gas? That thing should pull like mad on that size of a shot. nos make a teflon upgraded plunger for 30 bucks or so witch usually cures this.

rustbucket · #7 Post by **rustbucket** » Thu Sep 21, 2006 3:20 pm

its a new big shot kit. my bottle had a couple of passes on it and when i hit it off the line it felt like a mack truck hitting me in the back, and then after a second or so it nosed over so i let off the n20 and hit it again, it took off again and nosed over again. even hitting that hard i only had a 1.456 60ft "hooking".

#8 Post by **John_Heard** » Thu Sep 21, 2006 3:24 pm

Better figure out what the deal is. Is there a chance you were losing fuel pressure after launch? Did it pop or miss?

MOOSE · #9 Post by **MOOSE** » Thu Sep 21, 2006 4:14 pm

Better yet what did the plugs look like after that kind of pass. If you checked the plugs tell us what you found and i bet we can get real close as to what is going on.

MOOSE

rustbucket · #10 Post by **rustbucket** » Thu Sep 21, 2006 5:06 pm

It didnt pop or miss, it just went flat. i checked the plugs and they didnt look bad. The last time I ran it lean one of my heads looked like I took a torch to it and it also burnt the ground off the plugs. I going back this weekend to mess with it.

Racer704 · #11 Post by **Racer704** » Fri Sep 22, 2006 5:30 pm

You need to also know your bottle pressure and mount your fuel gauge for the nitrous in a place you can watch it. Pull the plugs at the end of the pass with a clean shut off and dont drive it back to the pits.

madness67203 · #12 Post by **madness67203** » Fri Sep 22, 2006 6:12 pm

rustbucket wrote:its a new big shot kit. my bottle had a couple of passes on it and when i hit it off the line it felt like a mack truck hitting me in the back, and then after a second or so it nosed over so i let off the n20 and hit it again, it took off again and nosed over again. even hitting that hard i only had a 1.456 60ft "hooking".

are u using a 10# bottle? How many passes can u get out of a 10# bottle setup for a 275 shot?

rustbucket · #13 Post by **rustbucket** » Mon Sep 25, 2006 11:00 am

I am using a 10# bottle, and have added a nos bottle heater. I didnt get to go this past weekend due to rain so im planning on next weekend. Im not sure how many passes i can get on a bottle yet.

madness67203 · #14 Post by **madness67203** » Mon Sep 25, 2006 6:24 pm

have u weighed the bottle to see how much nitrous is in it. My buddy was running a 250 shot on a 9.40 car and could only get two good passes before switching bottles.

rustbucket · #15 Post by **rustbucket** » Mon Oct 02, 2006 12:52 am

ok, went to the track today.With a full bottle and 900 pounds of bottle pressure, I staged and ran a 60 ft time 2/10's slower than a motor pass, due to extreme tire spin. (On test and tune they wont prep the track.) witnesses say I was fishtailing for 300 feet, and ran a 6.52 @ 105mph. Theres hope yet. I didnt change the jetting and feel pretty confident that its gonna go good with a prepped track. thanks guys for your help.

your opinion, will i hurt it?

your opinion, will i hurt it?

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