First, let me tell you about myself. I built my first engine about two years ago and have been hooked ever since. A true learning experience. Its a 355 mouse motor with vortec heads, a comp XE268 cam, steel crank, rods and hyper pistons. I built it to spec from a Chevy High Performance article. They dynoed the combo at 390hp/410tq. A great start to the world of hotrodding. Almost three yrs later I am gettin the itch to build a more powerful motor. Which brings me here today. I have never touched nitrous before. But I have several hundred hours invested scouring the internet and reading books on how to build a reliable nitrous motor. Meaning this going to be a 10 to 12,000 mile per year street motor that will see track time 50% of the time. The rest of the car is set up to take this punishment.This is what i am planning on building please tell me why this wont work!!!

I am starting with the heads, the valve train, fuel pumps (they are listed below) and a machine shop checked, high nickle 71' orange block, with aftermarket splayed main caps 4.040 mouse motor.Scat rotating assembly (for $1300 from sallee chevrolet) you get a 4340 3.75 stroke crank, 4340 i-beam rods (full floating and bushed) and good forged pistons(d-cup dished), get a premium engine rebuild kit ( for the nitrous you need great rings and head gaskets $200 out of jegs or summit),arp fastener kit($200 jegs) vortec heads modified for larger cam (from sallee chevy or scoggin dickey chevy from $650) compcams XE cam 262 or 268 ($150 from summit or jegs), victor jr. manifold($250 from jegs or summmit), holley, demon ($300-500 thru jegs or summit)...finally build it to 9.0 to 1 static compression, get a NXS nitrous kit 150 hp to 300hp adjustable ($450 jegs) without juice 400-425hp, but a flat 450lb torque curve that will be a blast to drive.

Now for the Nitrous System. I plan on using a Jacobs Nitrous mastermind controller($225 from summit or jegs) and a MSD ignition controller ($400 from Summit or Jegs). With the Jacobs box I can set the nitrous to ramp up to say... 5500 rpm's. So at 3000 it will only be at 25% of a 300 shot and it will be a full 100% at 5500 rpm's. One the street it will be jetted for 150 shot and at the track it will be set at the full 300hp shot. Also the Jacobs controller will handle all timing retarding needed.

One the fuel side i will be running at holley mechanical pump for the carb. I will be running a dedicated 2 to 3 gallon fuel cell. It will have 110 race gas in it. It will be pumped with a holley blue electric fuel pump.With the arp stud kit and the splayed main caps the block itself should be good up to 650-700HP.

LeeMoses

Forget the progressive controllers, they beat the snot out of the solenoids and you'll have to replace them far sooner than your wallet will like.

Pick a camshaft designed for nitrous use, wide lsa and a huge bias towards the exhaust lift and timing. They help the engine run smoother and you won't need a high stall converter, unless you pick a cam that's too large.

Start with the smallest jet combination on the nitrous and work your way up.

Get a converter with an anti-ballooning plate. I know the necessity of this from experience, it wasn't pretty.


Aside from that it looks like you've done good homework.

Larry

I appreciate your post Larry. Can you tell me a little more about the anti-balloning converter? Thats for the cam recommendation I will take a look at it...


LeeMoses

Here's a nice converter for a street car with a small-medium camshaft. At the bottom there is a little info on the necessity of a converter designed for nitrous use.

http://store.summitracing.com/partd...26&autoview=sku

This or a very similar cam from any reputable company would work fine for you and match the above converter very well.

http://store.summitracing.com/partd...40&autoview=sku

Larry

Thanks Larry that cam looks like just what i need!!! I am going to use a race prepped GM 200R4 overdrive trans w/ a lock up converter. I am going to search around and find a nitrous converter with the lock up function. I think this motor will be a truly streetable motor. I expect to see b/t 18-20mpg and I can use 87 octane w/the 110 race gas helping avoid detonation.

LeeMoses

I am researching the rings and head gasket best suited for a healthy nitrous motor any suggestions!?!?!


LeeMoses

Fel Pro's new MLS gaskets and Speed Pro plasma-moly rings are what I use. There are plenty of alternatives that work just as well. I stick to what I know works for the peace of mind it gives me.

Larry

thanks Larry with check out the rings and gasket recommendation


LeeMoses

The vortec heads are great, but they have thin castings which can crack under the abuse of nitrous. I think you will be ok if you only run around a 100-150 shot. As far as the progressive controller goes, I agree that your money can be better spent elsewhere. Unless you are going to be running a 250+ shot, you shoulden't have much of a problem hooking up. There are a couple of things that nitrous specific motors like. These will make the motor slower on motor, but it will react better when on juice. First, as was stated, use a nitrous cam, something with more lift and duration on the exhaust, and a 113-115 lsa. That way, you are not shooting nitrous out the exhaust valve. As far as the heads go, it is best to over head the motor a little bit. Nitrous adds almost twice as much torque as it does horsepower a runner that is too large would usually make the motor sloppy, then nitrous adds all the torque back in, and you have the flow numbers of the larger head. Again, your motor will not be as fun on motor, but watch out when you thow the nitrous at it. Another thing to think about with nitrous is gear and stall. When you use the nitrous, it will push your stall up higher in the RPM range, so it is best to run a little less stall than is recommended. Also, you dont want to run a bunch of gear. Again, you want to let the torque do its work. I think a set of 3.55 to 3.73 gears would work fine. If you did think about getting a different set of heads, I would recommend the AFR 195cc heads. They are expensive, but make great hp, and have really thick decks for nitrous use. This all being said, if you are only going to be running a 100-150 shot, and you want this car to be fun on the street also, I would design the setup mainly for running on motor, but get a nitrous cam, and dont run too much gear.

Adam

Adam thanks for the head and gear recommendation. I was looking into a race prepped 200R4 w/a lock up converter (anti-ballooning one if found) and a 3.55 rear gear. I have talked to several guys at the track where I run at they are all running 383's and 406's with vortec heads and 300-400 hp shots on a dual stage setup. So not to say that you are wrong at all!!!But this is the first I am heard of this. Can you tell me what the weak link on the heads are. Are you implying failure or reduced performance? As for performance, I am building this motor to run on the street with little or no nitrous, with a streetable power band of 2000 to 6000 RPM. Also i fudged the manifold, I think a Torker will be better suited for my powerband. I really appreciate your recommendations keep them coming.


LeeMoses

If guys are doing it and not having problems, then go for it. The head cracking thing is just something that I have been warned about. I used to have a 355 just like yours with an xe268h cam and vortec heads. As far as the intake goes, I would go with the performer RPM air gap. This is a great intake that will match your setup perfectly. I have never used the torker II but I have heard very little good about it. From what I have heard, it is an old design, that was an attempt to have a single plane that had dual plane mannerisms. The RPM is recommended for 1500-6500 RPM, that sounds perfect for your motor to me, and that manifold is a privet performer. I tried to do some research on the cracking issue with the vortec heads, but I could not find any conclusive information. I may have just been misinformed. What are you planning on running for a stall? If you would be ok running a 2600-2800 stall, I would recommend the NX274H cam (230 244 @.050 .487 .501 lift 113 lsa). I really think you would be happy with this cam. The reason that I recommend the larger cam than you had before is that the larger motor will make it seem like you have a smaller cam. Because of the size difference of the motor from your last one, the NX274H in your new motor should behave similarly to the xe268h in your old motor.

Adam

From Experience, Get the best ignition you can get. Nitrous hits the intake at minus 128 degrees, making the charge rather cold, it needs a fat spark to ensure good combustion. Also set the quench distance accordingly, anything you can do to help combustion efficientcy helps with nitrous use, as the better the mix, the more power made.

^I think the "hot plug" recomendation is backwards but, w.e.^

I didn't notice if you had indicated whether or not the block had been decked. Lots of block decking will react alot like a thin deck on a head. Thin head deck and/or thin block deck = difficulty controlloing head gaskets.

I dont run laughin gas and never have but I think that I would be certain that my fuel delivery was way overkill. I even guess that the holley blue wont be enough at the larger diameter fuel lines you'll need.

Was that a 2 bolt block converted to a 4 bolt splayed system?

Good advice DV but lets be clear that you shouldn't use hot spark plugs. That's a no-no with nitrous. Lets say powerful spark rather than hot spark, as in a stout coil and a CD type control box, to help keep any nitrous newbies from a possible meltdown.

Mallory's digital HyFire box pn. 685 will do everything both of the Jacobs and MSD will do and make wiring less of a nightmare. Use that with a matching Mallory ProMaster coil and there should be planty of juice to light it up.

I agree with Firestone on the slightly larger cam for a 383. I missed that in the first post.

Larry

I would go with more compression and an even larger cam. The 383 will have no problem making enough torque for the stop lights, so I'd lean a little more towards the upper mid range power for track use. Also, 9.0:1 is playing it plenty safe for a nitrous engine, and if you're considering going with 110 leaded octane at the track there is no reason to step it up some. I've seen plenty of happy 10:1 383's and going with about 9.6 or so will still leave you some room for safety and comfort. The intake is workable on a 383, but not really suited for the street- definitely not the cam you chose, so either go with a nice med/low single plane and a slightly larger cam, or keep the VicJr but get a cam in the high 280's for intake, and 290's for exhaust. Also, sligtly larger headers than you would normaly run on the street- maybe like 1 3/4 or 1 7/8 it depends on your nitrous use and your willingness to sacrifice some street manerisms.

For rings- I love TotalSeal Gapless, yea, the good ones cost twice as much as some others, but when you think about it the rings are the most critical part of the engine (they keep the pressure on the pistons) and spending around $250 for a nice set is worth it.

Take a look at the Fastburn heads from GM- a little better than Vortecs. The AFR's that were already mentioned are great too.

I just think that you're selling your engines potential a little short- don't skimp on the cam (383's have a long arm and like a fat cam to complement it), match the intake to your cam, your heads as well, give it some compression, and don't go cheap on the basics- after all its the basics that hold it all together.