How much nitros can my engine take?

[jerry S]

How much nitrous can my engine take?

My 351W was recently rebuilt. My crank is stock and was rebalanced and reinstalled with new main bearings, caps, and bolts. I have forged I beam rods and forged flat top pistons. My CR is 11:1.

I want a dual stage shot of nitrous with a progressive controller. How much can the engine safely take? I was thinking about 100 shot for stage I and 150 shot for stage II to be safe.

 

[351carlo]

If the block is stock, and does not have a half fill of hard blok or any reinforcements, I would be first concerned with the cylinder walls cracking.

That being said, I would go with a 200 shot total or less, preferably just a 150 shot. This is where I feel comfortable, and I have a very similar setup with a Cleveland block.

Make sure you pull timing, have your setup tuned in right, use a hobbs switch, I like the use of a window switch, WOT switch is a definite, and I would use some higher octane fuel with 11:1 compression.

In fact, most setups with compression as high as yours and a street motor I've seen the guys run 2 fuel systems. Standard motor setup, and a secondary fuel cell with dedicated pump for the nitrous system. Use premium gas for the motor, and then fill the nitrous tank with high octane race fuel.

 

[mustangman70]

Helli used a secondary pump just for my 100 shot lol

However we need more info man, what else is the engine containing? heads cam etc...

How about your exhaust, with a dual stage i would defiitly open up the exhaust a little more, maybe give those heads a nitrous port job....

Also what are you using for ignition and fuel currently?

Theres a couple of us nitrous junkies in here and i personally wouldent go over 250 myself so i think you might be allright, it just depends how much power were looking at allready N/A

 

[jerry S]

Helli used a secondary pump just for my 100 shot lol

However we need more info man, what else is the engine containing? heads cam etc...

How about your exhaust, with a dual stage i would defiitly open up the exhaust a little more, maybe give those heads a nitrous port job....

Also what are you using for ignition and fuel currently?

click on the "About my car" link under my sig to see what I have done to the car.

In a nut shell, I have an MSD pro-billet dizzy, 6AL box, and digital timing computer. Fuel is 94 octane. Exhaust is through long tube headers and 2.5 inch tubes with X-pipe. Heads are Edelbrock RPM Performers and will be ported. Here are the post porting flow numbers

Intake/Exhaust .100" 79/61
Intake/Exhaust .200" 145/121
Intake/Exhaust .300" 198/168
Intake/Exhaust .400" 241/178
Intake/Exhaust .500" 279/196
Intake/Exhaust .600" 284/205

cam is

ADV DUR: INT 297, EXH 308
- LIFT: INT 538, EXH 534
- DURATION AT .50 DEGREES: INT 236, EXH 242

rear gears are 3.70

I can even use a dedicated fuel pump for the nitrous. I have an electric holley blue for gas and still have a new stock replacement fuel pump on the engine just sitting there doing nothing. I can dedicate that for NOS.

I am currently at 400-415 NA right now (before the heads are ported).

I want to spray only as much as is safe for the engine.

 

[iskwezm]

backed when i worked at NOS, we wouldnt recommend anything more then a 150 shot on "stock"(pistons,rods,crank) internals. A block is a small part of the equation, but the internals will take the abuse first. I have ran up to 140 shot on my stck 94' gmc truck and ran 150 shot on a stock 96 cobra. I think 125 is plenty and 150 will scare you.

 

[mustangman70]

If your at 400 or so horsepower allready.... i think a 175 shot will do the trick

iskwezm...do you think that "stock replacement" pump on the block will be sufficiant enough for him to run a dual stage system?

 

[jerry S]

If your at 400 or so horsepower allready.... i think a 175 shot will do the trick

iskwezm...do you think that "stock replacement" pump on the block will be sufficiant enough for him to run a dual stage system?

What he said.


The only thing stock on my internals is my crank. How much juice can my engine take? Can I use my stock replacement pump in conjunction with my holley blue to run a dual stage?

Inquiring minds want to know.

 

[mustangman70]

It would "take" a 250 shot no problem....the fun part would be waiting to see how long that stock block can handle 650+ hp or TQ

Ive been under the impression that the stock pump would be fine for about a 100 shot, i may be wrong, but im a little parynoid when it comes to the juice and just to be safe i would throw a little upgraded holley or edelbrock mechanical for the spray, and of course use a pressure saftey switch!!!

 

[iskwezm]

If your at 400 or so horsepower allready.... i think a 175 shot will do the trick

iskwezm...do you think that "stock replacement" pump on the block will be sufficiant enough for him to run a dual stage system?

I ran mine with a Holley Blue up to 150 shot and newver had a lean problem. As long as the pump can sustain the needed psi, it should be fine, if it bleeds off under a load,then theres a problem.

use the block pump and kick on the Blue for the second stage if you like

 

[10secgoal]

I wouldn't go above 150-175. Try a super power shot, and a jacobs mastermind. Look into the description of it online. Wonderful little toy.