I'm building a 350 to swap into my '89 Camaro. Since I knew all along I wanted to juice it, I upgraded a few of the internals. I put Speed Pro forged pistons in it (Flat top 4 valve relief), as well as Summit stage II connecting rods. The engine still has the stock crank in it. How much nitrous can I use in the old girl? If a stock engine can use up to a 150hp shot, could I get away with using a NX 225hp shot? What do you guys consider "safe"?

 

I think you could do it, if the mustangs do it.

 

225 Sounds like a lot but probobly not to much just make it run a little rich and I wouldn't recomend it unless you completely know what your doing. Definetly start low though start at like 100 and work your way up like im doing. Dont even try it with the stock pump. Retard timing about 2 degrees for every 50. Just so you know I have seen alot of engines built solid like yours then they just end up blowing a head gasket. But hey head gaskets are next to free just a pita.

 

yeah my bad I assumed you had some nitrous expirience, dont just jump out of the box with 225. 383GTABoy is very correct.

 

If you try to go over 400-450 hp on a factory cast crank you are asking for trouble. That crank will being flexing so much in there you would think that it was doing the mambo. It may make quite a few runs or break somewhere fairly early. If you have the tune on the nitrous good i am going to say the crank will go first.

 

Minus Chronis-titan, where are you guys basing your info off of? Word of Mouth?

With your setup, I would not run more then 250 shot, chronis is right on the crank, I also have a stock crank, and did that shot but had a progressive system. Definte Second Pump is necessary. Always check your plugs and make sure your timing is right. I wish I would of went with a steel but it is too late

If you had a steel crank, you could do 350 but the engine would need to be pulled apart after a season for inspection.

For the head gaskets, if you have not put them on yet, call felpro and ask them what they recommend, I cant remember my part number, but when the heads came off it was fine.

 

what do you mean?

 

A 150 shot is fairly easy to tune for and you can still use the power. When you start shooting 200 up you start blowing the tires off. I usually go 2 degrees every 50hp and check the plugs. If there is no alum flecks on the white porcelin (piston detonation) up the timing a couple degrees and run it again, check it again. As long as the alum flecks stay away and fuel pressure is sufficient it should be okay. I've sprayed 250 on stock cranks with no problems just watch the plugs, if I remember too much timing kills head gaskets , low fuel pressure melts pistons.

 

I don't know how much horsepower you guys plan on putting down at the rear wheels but I am scared to run more then 150 shot in my car. #1 reason why is because I don't think my two bolt mains can handle any more. If I were you I would get the block machined for 4 bolt mains .

 

Actually a lot of people prefer 2 bolt mains, esecially in a 400. The outer bolts make the webbing in the block weaker around the mains. As long as the clearances are right 2 bolts are not a problem. The only way I'd bother with a 4 bolt is splayed main caps. I've sprayed 200 to a mexican block/heads motor with no problem. Just watch the timing and make sure of the fuel pressure and it'll be ok.

 

Now granted that I don't have a third gen block, but when I put my car on a chassie dyno and my numbers came up on the screen, the first thing the guys said in the shop is "Do you have four bolt mains." I said no why. They told me I better not do anything more to the car (motor wise), until I fill my block and get four bolt mains. Just for referance my car is putting down around 500rwhp, and 600rwtq. Like I said I don't no much about third gen blocks, that is just my 2 cents worth.

 

good call JC93Z, and for you 4 bolters the 350 4 bolt blocks are great and have thick webbing. the 400 (I now exclusively run) are best in two bolt for the afore mentioned thin web. my 412 interim motor is being given a few more upgrades to take more punishment before install, like a stud girdle and a short fill of Moroso block fill because it is .060" overbored and not sonic checked and will be street driven make no mistake. I'm just not totally sure what 14-16# of P1SC boost and 9.21:1 compression is goanna do to it. I also got a crane HI6-(w/boost reatard) to help save it.

 

My cousin runs in the fast street class on 10.5 tires and just yanked his 400 2 bolt stroker. It had the hard block, bored .060 etc. He was running a 300 shot off the line thru the 1/8, with 12 to 1 comp. Ran 6 teens in a 72 Chevelle, 3200lbs at 7400rpm. It was starting to crack from the head bolt holes in the block towards the cylinders. The crank looked good, the block was coming apart. If you wanna 400 look for the 509 casting block.

 

Cool...just ran out and checked mine. Sure enough, it's a 509. What is the significance of this casting? Very curious...thanks! Just ordered a forged crank...doing this one right the first time- no regrets. I'll probably just stick to a 150-200hp shot with this motor.

 

I don't remember all the details but I think it has a higher nickel content in the steel or something. The stampings under the timing cover tell the nickel,iron etc content in the block. Rest assured you have the best block, get some arp rod bolts to go with the forged crank and it'll be good to go. Also make sure and recondition the rods. Might wanna get some BFG drag radials, you're gonna need em...

 

Key is right. The 509 has more nickel in it. At least that is the rumor. It is probably a 2 freeze plug plug too which are also rumored to be stronger.

Good luck.

 

Many a discussion has been made on that deck crack from the bolt holes and the verdict has been passed by ARP and other fastener manufacturers that it is related to how the fasteners are installed. they actually said that a over installed head stud can cause that crack on a bowtie block.

 

Thanks for the info you all. It seems to have drawn all the big dogs in hehe. :-)

Interesting...mine says 207 509 under the timing cover. There is also a 512 and a G33 and it does sport 2 freeze plugs on the side.

I'm going with arp bolts all around. Also, cant skimp on the rods - going with H beam 6 inch rods with forged, coated pistons.

Traction will still be a problem, that's for sure. What kind of mileage have you all gotten out of DOT slicks?

 

as far as the street legal slicks go, l wouldnt reccomend using any on the street. some are decent, but if you can, just buy a cheap set of wheels and mount a pair of DOT approved slicks, and swap em out when youre racing. thats what l did. l bought some cheap U.S wheels brand wheels for 30 bucks. theyre not so bad looking, chrome with nice chrome center caps, mounted a set of hoosier 8 inch slicks on em, and swap em out whenever.

I had a set of bf goodrich comp ta's - they lasted for about 2 1/2 months of weekend driving and racing. imo a big waste of money.... street legal slicks don't nessecarely mean theyre streetable getting caught in surprise rain, and the fact that they just don't last maks them imo not so streetable.

my friend with a GN had a set of the nitto street legal slicks on and his blew out not twice but three times before he decided to finally ditch em

 

With the forged crank you ordered you could probly get away with a 300 shot. There are mustang boys running 300 on the stock short block. I personaly think if you built the motor to handle it go for the 400 shot. Ls1 guys are getting into 10's with the stock internal engine and a 250 shot. All i have to say is spray away. one of these days if i ever get a job i am going to build a drag car with atleast a 500 shot.

 

Not to insult your intelligence, but remember the NX kits dyno thier jets at the wheels. So that 225 is almost 260 on the motor.

 

NX kits are also leaner the some other makers kits. I like the power they make but you gotta watch the plugs..

 

On the other question from JucinGTA, I'm basing my info from 20 plus years of racing all kinds of cars and all makes of motors, even a rotary rx7. I've tuned Nitrous kits from five different makers. I've yet to loose the bottom end in a 350 or hurt a part from nitrous. I don't know it all by any means but I WILL ask someone who knows when I'm not sure. Not to flame but you asked. I do agree that you need the manufacturer jetting with you at all times, when you need it it's priceless.

 

Keyz28, since you are the man with much experience with N20, I would very much appreciate some advise from you also.

I have a Compucar TPI plate kit. I am wanting to run a nozzle instead of a plate setup because of throttle body clearance issues on my TPI retrofit. The nozzle I chose was a single NX brand Shark Nozzle which is able to handle a 200+ hp jetting. It is placed in the intake ducting.

I was wanting to know if my compucar kit is rated at the rear wheels or at the flywheel because I need to know what maximum flow the compucar solenoids will take and if I will be needing to upgrade my solenoids. I am not certain, but I belive NX rates their jets at the rear wheels and Compucar rates jets at the flywheel. As you can see, mismatching this setup could prove to be a costly mistake if the mixture goes lean due to the gas solenoid being too small. I want to use the NX jets and nozzle to 200hp ratings with these compucar solenoids. Thank You for your help on this mattere

 

I believe you are right on their ratings. If I were you I'd call NX and ask for tech help, tell them what you are doing and they will recommend the right nitrous solenoid and maybe a fuel one also. What was the max hp rating on the compucar kit? You would be safer to get a fuel and nitrous solenoid that NX recommends. Then you would basically have their system to tune. Mixing components with success is sometimes harder than the tune.