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Discussion Starter #1
Alright guys Im debating if I should put a 150 shot on my 97 cat. I'm asking for input if I should or not. So far I got the block bored 30 over, Mahley rod's diamond flat top pistons, Cobra crankshaft, pi head's ported, stage 1 crower cams, getting a 3500 stall converter, 3.73 gears with posi, and all the other minor **** to get it all set. Should I go with a 150 shot or something a little smaller?
Any input is greatly appreciated.
 

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West Virginia Chapter Director /, MA Drag Race Te
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DMcBrideBoston said:
mnnn, smaller to start with...

like a 75 shot, and a nitrous tune , then bump it up during a nitrous DYNO tuneing session.
Good point!!! Just cause its built at the bottom dont mean it will live if you screw up.

Go small, tune for big then give her a whirl. Sounds like a good combo, Im interested in seeing the results.

:)
 

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Whining Intakes Rock
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Good advice to follow. Check your plugs after every run. Tune your fuel and nitrous at each stage and you'll last alot longer than if you went "balls to the wall" right out.
 

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Discussion Starter #5
Alright so once I get everything all back in and ready this summer run a 75 shot for a little while then bump it up to 150? Yeah I will check the plugs too, now doing that should I check all of them? Sorry for the question's I was never real big on Nitrous, but too many guys saying there gonna beat in there pos car's that won't pass inspection lol. Thank's again for the help!
 

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Whining Intakes Rock
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The right thing to do is check all plugs immediately after each run down the track. The longer you wait the less of a tell-tale the plugs will be. You're engine sounds like it should be able to handle the higher shot but what about your fuel? Starting off small allows you to adjust things along the way and possibly catch a lean condition before there is no doubt you have one. You'll know that when you blow the intake off the engine. (see JoelBender)

What kind of kit/system were you thinking about getting? Wet or Dry? Do you have a tune and what's your fuel pump /injector rating?
 

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Formerly Fdawg97LX
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sounds like u got a pretty stout motor, so if your fuel system is adequate go for the 150 shot. get it dyno tuned specifically for the 150 shot and u should be good to go.

Frank
 

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Yeah check that fuel system. The question is how much more can it handle?
 

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Discussion Starter #9
Man I didn't want to hear about blowing the intake off that's gonna make me second think this!!! Well I was thinking about going with the 255lph fuel pump with 30# injector's but I haven't got them yet. I will also be going dry. I heard of alot people having problem's with wet kit's whether or not it's because of operator error or what IDK. Im trying to do as much research as possible so I don't blow anything up or blow the intake off.
 

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Whining Intakes Rock
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It's mainly operator error. Dry is good. If you go with something like a Zex, the 75 shot will work fine with stock pump and 19# injectors.
 

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Don't let the negatives of a wet kit shy you away. Like AL said it is usually operator error. Wet kits in the long run make more power and are easier to tune.
All the intake horror stores you hear are usually from users who shot to early and ended up with a fuel/nitrous puddle in the intake. A window switch set to around 3000 rpm will keep you safe.
 

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Discussion Starter #12
ok so the stock pump and injectors are good if I only run a 75 shot but if I do run the 150 shot which injectors should I go with?
 

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West Virginia Chapter Director /, MA Drag Race Te
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Al_Florida said:
It's mainly operator error. Dry is good. If you go with something like a Zex, the 75 shot will work fine with stock pump and 19# injectors.
I've ran the ZEX 75-125 dry shot on a 255 pump and 19# injectors for years with no problems on a factory stock engine at that!

You should have no problem with the ZEX kit if it is installed correctly up to 125 shot with your set-up if its all done right. You STILL should get a tune to insure its all safe. You do need the pump to keep the fuel up to par.

As far as the wet kits, they do have the tendancy to make a tad more power but even if installed correctly I have seen problems and blown intakes on more than 1 occasion on our cars. And that is also with window switches set at 3000 RPM or higher. Can't say I've ever seen that on a dry kit!!

MIne has been and always will be on at WOT off the line and has served me well. No need for a window switch here. The TPS takes control of that.

Good luck in your mods.
 

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Whining Intakes Rock
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97qwikcat said:
if I do run the 150 shot which injectors should I go with?
That requires a little guessing and a little math.

You should calculate your fuel requirements to determine the size of your fuel pump and injectors.

The size of fuel pump is based on the brake specific fuel consumption (BSFC) of your engine. BSFC refers to how much fuel in pounds per hour the engine consumes per horsepower. For nitrous, you can use a bsfc of .65 I think I read.

The formula is:
(Estimated HP x BSFC) x (1 + Safety Margin) = pounds/hour

((lbs per hour / 7.25) = gallons per hour) x 3.785 liters = Liters per hour.

The safety margin should be greater than 20%. But lets use 20%. SM = 1.2

Lets assume (unless you already know) that your engine puts down 250 hp and you add a 150 shot. Lets further assume that that will actually add 150 hp to give you a total of 400 hp.

400 x .65 = 260. 260 x 1.2 safety = 312 lbs/per hour
(312 / 7.25 = 43.03 gph) x 3.785 = 162.89 lph

Since fuel pumps are rated at 0 lift and I don't have the calculation here for figuring out loss of flow per foot I would say a 190lph pump may be fine. You can go with the 255lph pump so don't have to worry about it.

To figure injector size:
((Power x BSFC) / # of injectors) x (1 + Safety Margin) = pounds/hour

Using above numbers we get 400 x .65 = 260lbs. 260 / 8 = 32.5 lbs/hr/ injector. 32.5 x 1.2 = 39 lbs/hr/ injector.

You could use a 36# injector but if you want that safety margin a 42# injector is what you would use. Although a 190lph pump would flow enough fuel to feed the 42# injectors on paper, it doesn't take into account lift. I would use a 255 lph pump with 42# injectors.

I hope my math is correct... :tongue:
 

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I agree also to go with the 255 pump. If you are going wet you do not need injectors as the nozzle takes care of the Nitrous and the fuel. If you do get injectors make sure you can get the chip or tune in your car before you decide to ride the car out to the dyno. As the bigger injectors will make your car extremely rich.
 

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Discussion Starter #16
alright so the best thing to go with is the zex dry kit, 255lph fuel pump, 42# injectors. Yeah also when I finish everything I will have it towed or take the flat bed from work and take it to get tuned.

I can't beleive this car started out as a grocery getter for an old lady and now it's only gonna be used for sunday crusing around and the track. lol
 

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Whining Intakes Rock
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I'm not sure there is a dry kit that can go to 150. Zex goes to 125. I can't remember off the top of my head what the others are rated. If the dry kit you plan on getting only goes to 125 then the 42# injectors would be overkill.

I'd still go with the 255 pump since dropping the tank is just a pain. Easy to do but I wouldn't want to do it again to upgrade my pump.

Wet kits also add fuel along with the nitrous which is why they are called "wet". With the added fuel, you could use a smaller injector or a larger shot with 42# injectors. If you want to seriously get into racing, I'd setup a wet kit and trailer your car to the track.

One other thing to consider is the cost of refilling the bottle. A 10# bottle will last about 7-10 runs approximately. Check if there is a place to refill the bottle near you and consider getting a spare bottle. I have only 1 place around me that sells nitrous. The only reason he does is because he uses it in his mustang. Otherwise he wouldn't bother because he makes no money on it. The cost to refill my bottle was $32.
 

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Formerly Fdawg97LX
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if i remember correctly the zex solenoids are good up to a 175 shot, u just need to get the correct jetting.

also i dont know if the nitrous will last 7-10 runs on a 150 shot. mine used to last that long on my bird with a 75 shot. i'd say plan on the nitrous lasting 4-5 runs.

Frank
 

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Discussion Starter #19
Yeah there is a place right down the road about a minute from me that sell's nos. I really don't want to get real big on racing with it yet for the fact that I don't want to put a roll cage in it. They make bigger tanks don't they or couldn't I run 2 10# tanks if needed.
 
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