Hey all, recently heard that nitrous is a really good bang for your buck power adder. Does anyone know how big of a shot of nitrous a 1981 corvette with stock internals could handle without any issues? Thanks.

 

None. comes to mind.
if you wish to break s@$t go for it. not just the engine , but everything behind it.

 

Those cast pistons engines will handle a 100 shot if you do the timing correct and the fuel side of the plate is functioning properly but I would NEVER put nitrous on an engine that had stock exhaust.....you can heat the exhaust valves up and crack them, plus you would gain maybe a 50 shot out of a 100 shot because of the miserable **** poor 81 exhaust.......but wait, there's more! Putting nitrous on the 81' CCC engine leaves it a crap shoot of how much timing to pull.....no telling what the ECM will try to do when the valve is open.
So, unless you have long tube headers, nice exhaust and a real mechanical distributor/carb to install.......I just wouldn't.

Jebby

 

I’ve got headers that go to side pipes, and deleted the ECM. I’ve also got an HEI distributor and an Edelbrock 650 cfm avs2 carb.

 

By stock internals I meant pistons, crank, heads, etc. Sorry.

 

Ok.....then 100 shot is it. Is the AVS 2 on an aftermarket intake or do you have that terrible carb spacer adapter on it? If you have the adapter......you need to either run a 2701 Performer EPS or put a Q-Jet back on it....

Jebby

 

I’ve got an edelbrock performer intake that the previous owner Installed. Would that work?

 

That is fine as long as that AVS is sealed well to the carb pad....
For 100 shot....you need to pull 4 degrees to be safe so set total timing at 32. I highly recommend a new fuel pump and pump gas that is of high quality....

Jebby

 

Thanks guys

 

Yeah it looks fun in the movies when someone pushes a button and they *GO* but it's not a matter of slap it on and you've got an instant rocket sled. The entire engine & drivetrain has to be built to take it. And you still might fry your engine.

The nitrous releases oxygen when it reaches a certain temp threshold and if combined with additional fuel makes a bigger bang in the cylinder. But the fuel ratio has to be balanced and delivered just right. A high-compression oxygen fire in your cylinders doesn't do good things to your engine.

It's something that hard-core racers do when they have enough money that grenading expensive engines and transmissions doesn't matter. If you don't fit that category I wouldn't monkey with it.

 

The only reason for "nitrous" around an '81 Corvette is if there is a small tank in the interior for the passengers to 'sniff' on occasion.

 

It sounds like a couple guys are echoing my comments above. Jebby is such a nice guy he actually gives you specifics.
If my Son came to me, owning your car and said, Dad, what do you think about nitrous on my 81?
I'd tell he he's nuts. and he WILL find the weak link. What will blow first? the Diff? the half shaft U joints? the trans? perhaps the rod bearings?
We should start a lottery!

 

AZ,
Another .02. Per Jebby’s recommendation and assuming your engine is healthy, I wouldn’t hesitate a minute. Have run Nitrous on assorted carbureted cars for over 25 years with no catastrophies. Just don’t get greedy, make sure ign is retarded as Jebby instructs, and ensure your fuel supply is efficient. Your car, your way. Go for it. To get all worried about all the perceived potential running gear breakage as a reason not to increase your horsepower is a classic case of the shoe telling the foot how big to grow. Again just my .02

 

Not a chance of hurting much if you throw a bunch of fuel at it and the timing is pulled......100 shot is nothing really......no different than building a 400 horse engine out of a Goodwrench 350 as far as stress on components.......and on street tires, they just go up in smoke, it is when you hook that you break ****.
But I will say this one more time: MAKE SURE you have adequate fuel supply to the plate.......the instant it goes lean, BOOM!

Jebby

 

P.S. And you're probably still going to get smoked by a guy with a stock Tesla. Go to 3:40 in this video to see a couple of nitrous Mustangs get left, along with an assortment of other cars.

 

Any 350 cubic inch [or larger] Chevy engine can produce adequate "FUN" if you set up the ignition system properly and have a decent 4-barrel carb [or larger] which is operating properly.

If you have a car with such an engine and it isn't "FUN", you either have problems with the ignition (retarded timing) and/or carb 'issues' (not opening completely, bad throttle cable, etc.) and/or serious mechanical problems with the drive train.

Moral: FIX THE EXISTING PROBLEMS WITH YOUR POWER SYSTEM BEFORE YOU THROW MONEY AT IT. Then, if it's still not fun for you, increase power however you want.

 

Sounds like a lot of advice from guys who have never actually run nitrous- or much of it. I ran Top Sportsman for years with a 565 in. nitrous engine; 500 hp tunes and never nipped a plug or burned anything. Went 7.17 at 192 in a stock wheelbase 63 vett in 2011. Here is the bottom line; just about any 8 cylinder engine will handle 150 hp nitrous hit. No need for an extra fuel pump or anything else if you keep it at 100 hp. If it were me I would run pump gas and pull 4 degrees of timing (although you probably do not need to pull any timing with such a little hit.)

Going lean does not burn up near as many engines as over timing them. You do not need a special exhaust, etc, etc. Bolt it on, make sure everything works, and have some fun. Good idea to weigh your bottles after they are filled. Assuming a 10 lbs bottle you will get 4 or so 1/4 mile passes out of the bottle at 100 hp. Once your bottle weighs 6-7 lbs. less than it did when filled, time to fill it again. Run your bottle at 900 lbs.

100 Hp with make about 150 ft. lbs.

Here is a video of my 7.17 pass if interested. This was back in the day when we used to bang the system through the engine. Fast forward to 50 seconds, You can hear the engine eat 500 hp at idle and then spin 8675 rpms at the shift. Car was so short it would not 60 foot at all; carried the front wheels all the way through 1st gear. It had 6 second MPH.

 

I ran nitrous all through the 90’s on everything that had a piston in it.....bikes, jet ski, cars....
Spraying through a stock 81’ exhaust with 39 year old converter and manifolds is stupid....you wouldn’t push 6-7 psi through a stock exhaust that can barely handle 150 horsepower but a 150 shot is ok....
Not running secondary fuel supply is stupid....
Sure....about any V8 can handle 150....but start at 100 and go to 150....which you will surely need a fuel side for.....
A 7 second NHRA nitrous engine has about as much in common with an 81’ 350 with a plate as Slayer does with Celine Dion.....
I built Nitrous engines for NHRA for years.....so what? 3 stage 632 Big Chief’s were bread and butter....
Obviously erroring on the side of caution was never in your vocabulary.....
Love it when folks jump in and just let me know how much I don’t know.....

Jebby

 

Have you ever actually flowed a nitrous system? Do you know how much fuel a 150 shot actually takes in volume of fuel? If not, then you oughta hold your opinion as to whether a secondary fuel system is required. I have not seen a secondary fuel system on a nitrous car in at least 15 years. Everyone runs one pump to make sure that nothing goes wrong with the secondary system- pump is not turned on, fails, etc.

My car was sponsored by Nitrous Supply (owned by the founder of NOS systems Mike Thermos) I assume you know who he is. Seven second cars is not all that I tuned; I tuned everything from my car all the way down to every day street strip stuff, big fogger tunes, plates, top shots, little tunes, etc. NEVER burned a plug, ring, anything I ever worked on. To say I did not error on the side of caution just shows how clueless you are about me. I was representing a company and could not afford to give bad advice or hurt a customers engine. I knew what I was doing. The reality is small tunes are very forgiving. You almost have to try to hurt something if you keep things around 150 or so.

My jobs for Nitrous Supply were testing, fuel and nitrous flowing, testing new products, R and D, etc. If you run a 150 shot worth of fuel into a pickle jar for 10 seconds it will fill about an inch in the jar- you need a secondary fuel system for that? LOL, no. Most people way over fuel and way over time nitrous engines. I did an educational video for Nitrous Supply 10 years ago where we filmed runs with my car and listed the nitrous to fuel ratio on my fogger / timing and run times. We went to about 400 hp that day with an 8 jet spread (nitrous bigger) and 19 degrees of total timing. 1050 hp 565 (14.5 to 1) Sunoco Max NOS 120 octane fuel. Nitrous system was not staged; all in at the hit minus a little timing staged for .75 seconds to keep it from blowing the tires off. This was filmed when everyone ran square tunes (same size jets on the nitrous and fuel side). I was trying to convince people to stop over fueling and timing their engines. Now staggered tunes are what everyone who knows anything runs, but back then guys were convinced they were going to burn this stuff up- so I made a video.

One last thing on fuel systems; I tuned a customers 71 Cuda; had a built 496 that made about 700 HP, NA, ran 10.6's. He wanted to surprise his friends at a test and tune so we hid a top shot under the air cleaner. Keep in mind the engine and nitrous system was all fed by the stock 5/16 fuel line. To keep everything hid I cut the fuel line connecting the duel carbs bowls and stole fuel going to one of the carb bowls to feed the 100 or 150 hit (don't remember which it was) So....... stock 5/16 fuel line, 700 HP NA, split the carb feed to fed a small nitrous system. We pulled 4 or 6 degrees and on a 5 lbs bottle he went 9.9 x. He ended up making multiple runs with that combination and never hurt a thing.

https://studio.youtube.com/video/_ZlqUWl9Ug0/edit

Btw; enjoying the debate- bench racing is a lot of fun.

 

It is.....it makes the world go round I guess......
When I say secondary fuel supply, I mean split off the one fuel pump and plumb to the opposite side of the plate...a tee.......I have not personally flowed system but watched as one was flowed (Big Shot NOS) and have a good idea of how much fuel is needed. Now....if you have a nice HP Holley, you could get away with spraying 150...an HP booster will recover quickly..but for the guy with a 650 Eddy AVS or equal will have trouble, these units calibration window won't cover fuel requirement that the instant 150 needs......not to mention the lag if it could. So you know that introducing it at the spray bar is the best way and idea.......the NOS is its own catalyst so you throw fuel at it, like a second concentrated atmosphere.....the engine revs when you bump a solenoid with the throttle blades shut.....which is another issue, throttle blades shutting quick and nitrous not so quick......lean spikes.
Anyway.....fuel side spray bar, 2 degrees of timing for each 50 horsepower is the safe bet......these cast 5/64th rings will only take so much abuse and a buffer from heat and detonation is a good thing.
Change my mind! LOL!

Jebby