I am going to try and post this pic.. My N2O hits good and hard off the lineBest 60 ft last sunday 1.53) and then it seems when i go into 2nd and 3rd it just doesn't pull as well. My best ever was a 7.28 @95mph(look in my signature) That was with a 175N2O. It normally has run88-89 mph then I decied to lock up the converter(yank slipped badly) it went to 95mph. This is where i screwed the pouch sorta of speaking.

I decide after running the 7.28@95 I thought if I changed to hooker long tubes,(X-pipe,true Duals), Changed to a 2 stage (added the dual shark nozzle and another set of solinoids), Walbro 340 Pump, Adj Regulator, and a non lock up ART CARR converter(4000 stall on N2O).

I have check Fuel pressure and found somewhere in the stock TPI rails there was a restriction at the fuel solinoid(psi drop to 20). So I tied into the fuel line before it made goes in the fuel rails..no more pressure drop. I have a solid 45psi(bottle psi950-1050psi).(thats what my jets are set for). I rebuilt both stages(plungers). Clean N2O filters, I am running AC 43 heat range(what I have always run) gapped .020-30" I change to see if it made any difference. I have normally run 6 degrees of timing(150N2O) on pump gas and race fuel for 175N2O. I pulled timing back...no change. I pulled plugs they looked fine..maybe alittle rich. I have had a scanner on the car while i am making a pass. NO KNOCK and mil were .875-.900

My car runs 8.20-8.30's on motor at 80-82 mph. I have run a compression test all were right at 160-165psi

When I installed the long tubes i had to move my Knock sensor over to the drivers side...could that be it? I won't think so.. but who knows. I wonder if valve springs could be it? they are about 2-3 years old...not sure. I have never had one act like this. It doesn't pop or spit.. just doesn't pull as hard as it once did.

Any Ideas?

 

Without actually seeing the car, I think:
- your stall speed is too high (even with the messed up yank you were able to lock it and after the launch it didn't make a difference)
- your tune is probably somewhat messed up
- if you were running it before with less pressure going to the N2O setup I'd bet that you're running way rich spraying. Remember that N2O manufacturers jet their stuff to spray about 2x the gas you actually need. Leaning things out will make you go faster (but will also make you more likely to carry your engine home in a bucket when something gets messed up)
- I think that the plugs are too hot and you're retarding the timing too much (although a lot of people spraying are running similar timing)

 

The car just about aways runs 7.60's. Just the yank was so loose(would slip to 5500-5800 175N2O shot) I decide to lock it up. Yank was blaming my tranny for the slippaged. So that is the only reason i did. I don't think my converter is to loose. It will flash to 4000 ON the bottle and 3200 on motor. It it about 1500 tighter than the yank(not locking up).

My bottle pressure is what I have always run. I try and shoot for 1000psi and my fuel 45psi. Thats what my jets are set for. I don't pull any timing out for 150N2O...maybe just 2 degress on a 175.unless I am running race fuel. Stock timing is 6 BTDC.

It ran 88-89 mph Sunday.I even grabbed another 50HPN2O on the second stage... it revved alittle quicker..but not much change in mph.

I pilled up to 175 and 60ft dropped , but then the mph fell 86-87mph. I am not sure. My friend just bought a chassis dyno and I will go see what is up with it.

 

Thats too much converter for a nitrous setup. You are skipping over a ton of low end torque because of the converter you are running.

As for the high rpm problems, have you pulled your plugs and checked your ignition system lately?

 

yank is very good at blaiming everything else when there is a problem. There stuff is great when it works, but…

You're still running too much converter. Based on the rest of your setup that you listed I'd bet that you'd go faster with about 3200 on the N2O, but it would hurt you NA… choose your battles. A good compromise would be to use something in between that you can lock up.

Woops I misread (I thought that you were pulling 6 degrees).

What I was saying is that in your original post you said that you were getting 20some psi originally. My point was that with the stock jets you'd be making more power at 23psi then you would at the rated 43psi… It wouldn't be as safe a tune but it would run faster.

 

I had a 2800-3200 stall(on bottle) and this thing was a turd. It would bog with 125HP N2O. I was afraid of pilling up and filling the motor with more N2O and it bogging. I mean bogging in a way of to much traction and not enough motor. I have a hot cam with the lower intake,SLP runners and plenum are siamesed ported ALOT. I really don't need any more torque..look at my pic and my 60ft time 1.53.. I have already broke the rearend 3 times. Any more and I will install my 9". My engine feels pretty good and pulls good to 5500. and shift little over that... I also shift at 5000 and slowed down.

 

If it was bogging its a tuning issue. Loose converters wont last long behind a healthy dose of nitrous. Look at all the seriously fast nitrous cars running in the 8's and you would be surprised how many are running 3000-3200 rpm converters with a lot more camshaft than you have.

 

What trans are you running? Is it a 700r4? I had a converter built for mine and love it. It is a "Neal Chance Racing" converter. With the 350 and a 125 shot I was running 7.70's at 88 mph with a 1.64 60'. Now I have a 406 and off the bottle it ran 8.06 with a 1.72 60' and trapped 92 mph. http://www.racingconverters.com/

PH:316-542-9869 Ask for Marty Chance.

Also, what rear ends are you breaking? I am running a 10 bolt with stock axles and an Auburn posi with richmond 3.73's. I'm a little worried.

 

^^^^^^^^^^^^^^^^^
My post from this thread:
https://www.thirdgen.org/techbb2/sho...hreadid=223734

 

yes I am running the 700R4. I have just about everything you can do(that I know of) to a 7.5 rear end. I have upgraded Moser replacment axles(35% stronger), Torsen Carrier,Richmond 3.73's, TA Girdle,Axle tubes weld, Solid spacer...no crush sleeve. I didn't have any problems it until I started running in the 1.5 60 ft range.

I know I have the best converter that I have had in it to date. I have run the stock converter(26" tires), a 10" 2800(26"-28" tires) , Damn YANK 9.5/12" converter(lock up 26-28"), I now have a 9.5" Art Carr (27"). I can still run about the same on motor ET wise(60ft off alittle) and mph about the same. The only way I could run the tight 2800-3200(ON bottle) is with 26" tall tires, I even run drag radials one time to help mph. NO luck

I ran 88-90mph(1.56 60ft) with that LOOSE yank(not locking up) I soon as I grabbed the bootle 5200(125hp) 5500(150) 5800(175) it would not come off that rpms until I revved it past that point. So I had less than a 500 rpm window from shifting to redline.

Now I have one that is a 4000(at the most) with 150(1.53ft) and my mph is about the same 88. I now have a 1500 rpm window(4000-5500) instead of 500(it was past my peak anyway)(5500-6000). So this converter is alot tighter than the yank and should reflect sometype of mph improvement. ITS NOT

I have a T400 with a brake and (4000)with lock up converter I might throw in it to see what happens(along with the 9').

ALso I am thinking of taking the long tubes and dual 3" pipe off and seeing if the hooker shortie and Flowmaster 3" cat back will help. I just have stock heads so maybe the smaller 1 5/8 headers and single 3" will help. Not sure. I thought that is might hurt me ET on motor(dual 3") but I figured it would help on the bottle.

My friends dyno is up and running..he is waiting on the wide band O2 to come in.

 

put a scan tool on it to check for knock

 

i did the last time i ran...no knock.

 

We I dynoed my car today. On motor 331HP and 400ftlbs. I sprayed 75HP N2O and it went 365HP...then I swapped in the 175HP it went 375HP. 480ftlbs..alot more N2O but 10 HP more. So I took off my entire kit and swapped everything but my old Single nozzle. I used my friends BIG SHOT set up, but with my single fogger nozzle. With 175 N2O it went 529 HP with 750+ftlbs
Damn TPI HP was flat (500+) between 3200-4300rpms and then dropped to 480HP 4400-6000rpms. Damn I was happy! I gained almost 175 RWHP and 300+ftlbs

Well We started back tracking to see what made the most difference or to find the problem. Here are the gains

Different(bigger) solinoids and -4 line to nozzle( old -3AN) 26HP+
Bigger -6AN Bottle Feed Line (from -4AN) 35HP+

HERE WAS THE MAIN PROBLEM DUAL SHARK 110HP+ NOZZLE)

the Nitrous Express dual shot nozzle(shark) . I took it apart and cleaned it( not dirty). The dual shark nozzle CAN'T FLOW FOR %$#@!. iT IS THE SAME SIZE AS THE SINGLE SHARK, BUT IT HAS 4 PASSAGES INSTEAD OF 2. This POS was the problem since last summer. Monday I am calling Nitrous Express and cuss them like dog and want my money back.
I can't wait until tomorrow at the track(hope it don't rain)

 

Wow, I'm glad for you. Doesn't it feel good to finally figure out what's wrong? You'll more than likely be in the sixes now.

 

went to the track today and finally got do make a good pass after 9 months. I didn't deck it off the line like i have been since it is making more power..I didn't want to snap the rear end again. SO I waited until about 20-30 foot out then grabbed it.

First Pass (taking it easy,bottle psi was low) 1.81 60ft 7.67 at 93mph

Second pass(little harder,bottle psi ok) 1.61 7.28 at 94

Third pass( Little harder launch, run out N2O)1.54 7.28 at 91

Forth pass(switched bottles, same as third) 1.54 7.13 95mph
The 4th pass i had to wait along time in the lanes and my bottle psi was borderline(low 900psi) I normally run 1000-1050psi

I plan on installing my 9" and sphon torque arm before may(first REAL STREET EFI RACE in paris,tx this year) I want to pill up to 200HP and leave right off the line.

Thanks everybody for there help.

 

Great times man. Congratulations on the fix.