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Nos help

1K views 15 replies 4 participants last post by  boostdcoupe 
#1 ·
Hello all new here been lurking for awhile.
I have a 88 notch with a gt40 plate kit. I think it's the big shot
It came on the car and the guy was not sure of the jets.
It has 2 fuel side .30 and 2 nos .42

I have been searching trying to find out what size shot this equals
Have not seen anything that explains the 4 jet sizes.

Can someone help out?
Thanks
 
#2 ·
The mods on car are. Gt40 intake, patriot freedom 185cc sct chip 2.02 intake valves and 1.6 exhaust valves upgraded springs on the heads hardend pustrods full rller rockers 1.6 ration comp cams nx282hr 306 forged trw pistons main girdle and windage tray moroso oil pad AOD trans with art car internals one piece input shaft lentech valve body/trans brake 8.8 rear 3.73 24lb injectos c&L maf 65mm bbk throttle body msd 6 plus nos plate kit. 28x10 rear tires
Any thoughts on what car had done. I'm planning on going to track once I figure out the jets
Thanks
 
#4 ·
Someone spent some money, that trans isnt cheap! And thats a good size cam for a 306. It should like the juice with that too.
 
#5 ·
So that seems like a lot to start out with should I lower the jet size and work up say start with 100 shot or 150 what would the jets be for that? Could someone explain why I have two jets for fuel and two for nos. Is that how they get the larger shot?
Thanks
 
#7 ·
iirc, the old plate (the one you have) had two fuel jets and two nitrous jets, one fuel and one nitrous fed each end of the plate, basically the plate was split in two and each half was fed seperately. the current plate has one set of jets and is fed from the rear, jetting on the current setup for 200 is 71n/42f, close to what your jets would come to together.

if you cant find the old jetting suggestions, you could just take the current jetting and cut it in half for each half of your plate. you can find the manual for the current setup here...
http://documents.holley.com/199r10329rev2.pdf
 
#8 ·
on second look, using my theory (totaling the jets and comparing them to current) your jetting would be closer to 250-275... i dunno bud.
 
#9 ·
Interesting how the NOS plate is setup. I like that it splits off.
 
#10 ·
Ok i cant post a link to the thread , so ill just lust the jet charts .
The most recent ... and richer settings from nos were
150hp 38/24
200hp 45/30
250hp 55/32
275hp 63/36
325+ hp 73/42 .
The older , jet chart that was alot closer on advertised hp
150hp 39/22
200hp 47/26
250hp 55/28
275hp 63/36
300hp 73/41
Nitrous is always the bigger jets . Hope this helps
 
#11 ·
Nitrous is always the bigger jets . Hope this helps
I just wanted to mention, this is only true with Hi pressure fuel, EFI stuff. Low pressure setups (carb, standalone, etc) are sometimes square jetted and fuel can be bigger as well. Jet maps are basically a starting point to tune from.

Thanks for posting the jet maps for him. I couldnt find anything.
 
#13 ·
Personally, i think thats a little small of an estimate. A .48 jet thru a single nozzle is good for a 100 shot (88 to the tires), so normal logic would say to double that, but they guys at nitrous outlet probably know better than me.
 
#14 ·
Still been figuring things out on the car. The timing was set to 18 deg that seem really high so I set it back down to about 10deg.
I have a few more questions
I have the msd digital 6 is there away to test to make sure it will retard the timing when the nitrous turns on. Everything looks to be hooked up correctly how do I double check?
Also was wondering since there are two nos and two fuel could I cap two of them off to cut the shot in half? While I'm learning things?
THanks
 
#15 ·
first... dont cap off anything, you have nitrous going to some cylinders but not all... theres no telling what kind of damage you will cause lilke that.

on testing the retard... simply connect a timing light to the running motor and trigger the retard on the box. i.e. with the bottle closed (disconnected would be better) and the fuel side disconnected (capped) do whatever it takes to trigger the system and see if the timing drops to the expected setting with the timing light.
 
#16 ·
it would be better to just disconnect the wire from the kit that triggers the retard and trigger it from another source.
 
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