300 hp NOS shot on a 360ci.

[Way2QWK]

I am currently running a 200hp NX plate system, with seperate fuel system in trunk on my stock 30,000 mile longblock 360. It feels like 12's on nitrous. On the motor it is slow due to low comp and stock heads, and mild cam.
I would like to run high 12's to low 13's on the motor and jet up to a 300hp nitrous shot. What would my 360 need to be fairly reliable to handle the increased nitrous. Im not looking for anything exotic, and would like to use cast crank and stock rods. Would lower comp ratio (9.0 or less) be better for more nitrous due to less cylinder pressures?
The 360 seems to be fine on the 200 jets, Plugs are good and Im running good gas in the fuel cell, and stock tank, colder plugs with less gap, and 8.0 comp. So it should live with forged pistons, studs, careful assembly, and more precise tunning.
Am I just dreaming or is it possible with a mild 360??

[DartMan360]

Well so far you have done everything right with the fuel system set up. I would say 200hp for a stock motor is pushing it by alot. It could be done but for how long it will last know one knows. I would say for the new motor go .30 over so you get a clean bore and wall. Go with a good nos piston. I have heard Ross makes some nice peices. Expect to pay high doller for them but that is what you will need. As far as the cam goes I would not know the set up you would want. Which heads do you have? Get a nice set of heads and open them up. Get the car running 12's on all motor. With a mild set up that would not be hard. Then with a 200hp shot if everything is working ok you should be running 10's. One of our good friends has a mustang with a fogger system. He bought everything seperate and built it him self. On all motor he runs 12'50's on a mild small block ford. With a 175hp shot he runs constant 10'50s on 8in slicks. It was not easy to do that as the car has stock suspension and everything else but it can be done. Call Ken at Hensley. He would give you the best advice on what to do. Also pick up a could books on nos and building a nos motor if you havent already.

[cdignition]

The best way to think about when building a motor like you want, is to build it for a Horsepower level....If you are looking at 350 HP on the motor alone, then a 300 shot, Youll be looking at around 600 HP engine. This will require a better oiling system, better rods, better crank, Pistons will need to be JE Forged for NOS use. ALos need to ust the right rings, and gap them accordingly...The heads will need to flow alot, and I would not use a NOS only cam...Build it with a Normal cam, and add the NOS shot. The one thing to remember is MAke sure the rest of the car is up to the task first....MAke sure the rearend is a good Dana, or a beefed 8 3/4. MAke sure your trans in Built right, and you are using a good Race Converter...USE a converter with ANTI balloning plates. Then make sure it has an 8 point cage, and frames tied, minimum. Then fron suspension needs looking at.....


If you miss these things, then the money you spent on the motor can be wasted.

[PRO]

Yikes!!!! your addicted to power!!!!!!(cool)but a stock block has its limitations,in this case the main webbing,its can only support around 500-550hp max,so if you run a 300hp shot you can only make 250hp on the motor which your probably already doing,also the rods are your weakest link with the 200hp shot,the "compressability" of the rod is usually where itll come apart,reconditioned rods are not acceptable in a N2O motor,in fact even the SIR new rods would only have a marginal level of safety,youll want either the manley or some other H beam rod for a real world motor,there around $489,main studs for sure,the lightest weight forged piston you can afford,be sure to balance it and run half grooved bearings and blend your oil ports at the filter passages,use a windage tray and aftermarket main caps would also be in order.I ran almost the same combo for years that you are,including a stand alone fuel sysytem for my N2O,67 Coronet,8.5:1 440,4 spd,3.91s,it ran 13.70s off the bottle(@4600ft)and 12.33s with a 150hp shot(11.88 corrected) with an amazing 1.49 60 ft with slicks and it was a backyard ring and bearing rebuild!!!,it ran 4 hard years w/no probs but eventually I wanted to go faster too,have fun........PRO.......

[Way2QWK]

Thanks for the tips guys. A lot of good points I had not have thought of. I diidnot know the rods are weak points in the motor.

Would a stroker combo be a good idea on a nitrous motor, since I would need better rods and crank and pistons?

[DartMan360]

LIke pro said about the max hp level the block could take. I think the stracker motor would make it worse for you. I would rebuild yours using the parts everyone has said here. I have not really read up on the JE pistons but know alot of people that run Ross. Some on the bottle and some off the bottle. Rember to start out small. LIke around 150hp shot. You also might want to look into a fogger system. You can save amost 2 runs on same about of hp. Which on average of 10bucks a run thats 15-20bucks extra. Well worth the extra money to build one. And since you have the selniods and everything just go buy the foggers for 30 a pop and drill them into your intake. I would say if you put some money into the motor you have now 12's should be in easy reach. Then add a 200hp shot and that would put you if not is real close to 10's. Even running 10.99 and faster is where alot of saftey stuff comes in. Stuff is not cheap eighter like a tranny and converter sheild. Also just getting the car set up for that much hp. In realty it dont seem like alot but it really is.

[cdignition]

Im no small block pro, but I would bet the block will take more that 550 hp...I have seen some 8 and 9 second small block cars running alot of snot(and with factory blocks, not aftermarket)....It will take some planning though. Alum caps, and possibly a girdle.

I will say this....Build the biggest cubic inch stroker you can afford to build...especially when you are getting new rods/crank/pistons anyway. Just make sure the heads flow enough to support it....more Inches means you need more flow. Just research and Plan ahead....and go with all the Compression you can afford gas for...it is free horsepower.

[Way2QWK]

ttt

[Rob Voyles CA]

Hey guys...how much fuel are you guys using out of your N20 fuel tank? either, per bottle of N20 or per run (and with what size shot?) Basically, I'm trying to deciede on a tank size for the nitrous fuel (I wanna put race gas in the Nitrous tank and And premium in the main tank). Some guys around here say they use a small fuel cell from a junior dragster for the N20 fuel cell.....and that its more than enough for a full nitrous bottle. Those little cells (1 QT?) are only $30 from summit.

[DartMan360]

The guy that has the mustang I was talking about has a 5gallon cell. He fills it up and it will last him the hole day. He is using a 175hp fogger system. Summit has these 5gallon cells on sale last week for 50. I still do not know if they have them and I think you can only get those prices on in store purchase.

[cdignition]

I run a 5 gallon cell in the trunk for main fuel system....When I reinstall the NOS on my car, Ill use a 1 gallon cell up front next to the radiator. All you need to do is re fill it between rounds...I run a 175 shot, but can go to 400 if I want to, hehe

[Fast One]

A fellow near where I live pulled a 10.90 some weeks ago at our track, 200 plus Nitrous kit ( can't remember the exact HP kit ), 360, cast crank, stock stroke, factory rods, JE pistons, 915J heads, flowing about 550 HP & all the other usual bits & pieces.

How long will the factory rods survive ? Your guess is as good as mine but they seem to be holding up pretty ok..

[Jims451]

Some weak points to consider:
Blowing head gaskets, Use head studs, maybe "O" ring heads or block.

Connecting rods, use aftermarket with good rod bolts. If this is a race engine consider Aluminum rods to soften the shock from the nitrous.

Block, might be OK with main studs, but a race block would not be out of the question when talking 600+ HP.

Forged light weight pistons, The lighter weight pistons will put less stress on the engine. You may want to talk to the manufacturer about the position of the rings from the top of the piston for nitrous use. Piston ring gap will be critical when using large amounts of nitrous.

Crank, the cast cranks seem to hold up pretty good, but a forged crank would be better (but more expensive.) The 4" stroker crank is also a cast crank. I would think a longer stroke might help control the cylinder pressures in the chamber (piston moving away from TDC faster), but the longer stroke will also put more stress on the crank and rods.

Cam, A nitrous grind cam that has a quicker opening exhaust to help blow down the cylinder (less pumping loss) and a wider LSA to reduce overlap.

Nitrous controls, Maybe a progressive nitrous controller or multiple stages so the full nitrous hit only occures at higher RPMs. Also, an ignition retard or programmable ignition curve to prevent detonation.

[one bad dakota]

I've been running a NX 200 shot on my magnum EFI 360 for two years. I have added Eagle H-beams and Ross light weight pistons with good rings. The crank is stock and the motor is studded top and bottom. It puts out a estimated 600 HP(500 RHP on a 150 shot). My biggest problem is with keeping a head gasket in it. This usually happens off the line and my stall is 3600. A progressive system is nice because you can soften the hit and lower cylinder pressure when piston speed is slow. A lot of guys don't understand that hitting it at a low rpm is much harder on parts than holding it out at say, 6000rpm. With N20 flow being relatively linear that slow piston speed increases fill time and makes for tremendous cylinder pressure.
With your type of block, I would personally only run a 300 shot with a progressive. I don't think you'll be happy with a straight 300 shot in terms of reliability. You can upgrade the assembly all you want,but in the end it's the block that will doom you. You could hardblok it or put a main support in, and that will help,some. You must also religiously avoid detonation. Run it fat, watch the timing, and run the coldest plug you can stand. Make sure the rings are gapped appropriately for N20 use.
Good luck,
Tom

[Way2QWK]

Thanks for the replys guys. I'll start saving up, and play with what I got for now......

[Way2QWK]

Would a 440 be more suitable for large amounts of nitrous over a small block???

[DartMan360]

As far as the blcock it dont matter. It is what is inside is what makes the difference. Pick up a couple of NOS books. Read read read..and when you think you read everything read some more. It helps out big time.

[PRO]

A 440 has a very stout bottom end even in stock 2 bolt form,I know of several stock blocks that have lived under 670hp for many years and a block thats filled can go very near 800hp.If you look at a BB youll see the pan rail is flat,actually the crankshaft centerline is about 2" up in the block and is reinforced from the pan rail up.this adds some weight but also adds some bottom end stability.So you could build a 400 hp 440 and add a 300 hp shot as long as you use main studs,4 bolt mains would be good here,steel crank,aftermarket rods and forged pistons,......PRO...

[leon441]

First get a block 70-71 360 or preferably a 68-71 340 block. Buy a steel 4" crank they are available mine just came in friday, and they are available for 340 or 360 blocks. Get a set of splayed 4 bolt caps from diamond racing. Fill the block 3/4 way with block filler this will dampen detonation and strengthen the block. Bore the block to 4.100" this is safe. This will make 426 cid. Since you are using nitrous the heads are not as important as normally aspirated. But get some elderbrock's they have 2.02 intake valves or the new Indy heads are a lot better but a considerable amount more money. You would probably find that you didn't need Nitrous anymore. Ross or Diamond Nitrous pistons. Use a sealed power Hell Fire ring and gap to at .026 and second at .020. I would recomend you call Muscle Motors, Indy cylinder Heads, or myself if you need help doing this. I ran those stock blocks for years but have stepped up to R3 now with W8 heads and without a real big wallet and an excellent car chassywise you would be in for a lot of trouble.

[Prochargedmopar]

Have heard of many go past this and hope to do it myself one day.

[LA360Dart]

Hello All;

One of the magazines just had (ok a few months ago) a 440 that made right at 500 hp on Westech's dyno. The engine was a stock rebuild like a 440 sixpac bottom end, mild hydrualic, with a single 4 bbl. The next thing they tried was Nitrous and when they stepped up to the 250 hp set up, the heads lifted off the block puking coolant everywhere, I'll look for the articile and give the magazine and month. As I remember cylinder pressure went though the roof and over came the clamping force of the stock head bolts.

Denny

[DartMan360]

WEll that sounds like a stock reubild amost. 250hp is way to much. They say a stock motor can only take 140-150hp shot at most.

[one bad dakota]

Agree with PRO on the 440. It's much stronger than the 360. Be careful with a big stroker and a lot of N20. Those rod angles start to get crappy and the side loading on the pistons isn't great either. Maxing out a blocks HP limit by using N2O is the last thing a shop will recommend. There are safer ways to do it,howbeit more expensive.
Tom

[Fast One]

Just as matter of interest Herb Mc Candless pushed a factory 360 block with cast crank to 630 HP, no block fillers etc.....

[LA360Dart]

The guy that had that pretty Blue Demon in HOT ROD about a year ago had a W5 headed stock block and #1 cylinder split on him. His Demon weighed right at 2900 lbs and car went 10:90's. Once you execeed 500HP on most production blocks you run into the first weak link in the chain the block, several racers I know agree with that on small blocks anyway. Their experience has been that unless a lot if checking and preperation was completed before working the block that hard. Early blocks are thicker in the bore but rare now.

[leon441]

Some guys talk about engines based soley on what they read in some magazine that didn't know crap. Some rely on what some parts salesperson tells them. I for one have a little experience at what a smallblock will take and what it will not. Early blocks are 360's up to 74' they can be bored to 4.100" safely and make over 700 hp reliably without fillers or trick main caps. 1971 was the last year for the higher nickel content blocks that is why I reccomend using one of these. A 340 block means a smaller main journal therefore it will require less oil to maintain lubrication to the bottom end. I might add put a #68 holley jet in the oil gallery feeding the head on both sides of the block and smack the hole with a ball peen so it will not fall out during disassembly later on. If you o-ring the block and run copper gaskets and use head studs this head lifting problem does not exist. Another person wrote of rod angle problems. If you plan this kind of horses why would you even think of using a short rod with a 4" crank anyway. You have a deck of at least 9.580" stock so there is plenty of room for a longer rod. I run a 6.385" with a 4.125" stroke right now and that's with a huge small end of the rod aka Bill Miller series 500. So unless you are sure about what you are talking about DON'T SAY ANY DIFFERENT!

[one bad dakota]

I'm not exactly sure who your referring to, but you did a nice job of muzzling any more useful info this guy might have received from others. What makes you think your limited anecdotal evidence is better than someone elses? A reliable 700HP on a modest build,huh. Are you refering to making that on RPM or N20?I love to see that motor go through two seasons of weekly bracket racing. Perhaps your definition of reliability and mine are different. BTW, I've run 600HP on my 360 for two years and kept it together, except I did it with a magnum block and the stock EFI. This isn't my first rodeo either. I also don't run it at that level on a weekly basis either. Perhaps if I had your wrenching skills I could.
Tom

[Fast One]

Don't recall hearing about a Leon441, his claim to fame doesn't ring a bell to me, now Herb Mc Candless I've heard plenty about him over the years, a good guy & someone you can trust not to tell crap in a magazine or in person.

[leon441]

Somehow Bracket racing to me means to allow a person who doesn't have the capabilities to go as fast as others a chance to race. To me that means if you try to make more power than the other guy this isn't the ideal way to race. In fact I don't see bracket racing as a form of racing although I do see the sport of it. I prefer heads up racing, this is where the one who does the most to go fast and suceeds, wins.

Now that I have cleared that up. The W5 engine that split the cylinder if we are speaking about the same article was a late model block and didn't have as thick a cylinder wall as the 74' and older blocks. I start racing in February and don't finish until November. I generally show up at a track on Friday and start testing. I will make about six passes and use up about 20lbs of NOS. On Saturday for qualifying I start with five full 10lb bottles and I always start each run with a full bottle. After elliminations on Sunday I go home. Between the big races I go to Piedmont Dragway on Thursday and Saturday and test and tune at this eighth mile track. My engine will consume 40+ lbs of NOS between the two test sessions and one big race. I ran the same smallblock engine from Feb 98 thru March 00 and from then to now I've been running my W8 combo. There are no bracket racers in my area that put the same amount of passes on their engines despite the fact that they are not making this kind of power.

As for the 440 blocks it is my understanding that the main webbing is stronger than a small block but the caps are weaker.

[Prochargedmopar]

Leon,
If this is so and it takes that much abuse then your machine shop must know it's S.........! Can we say slick, straight, smooth, and round?. go go ARP.