How much Nitrous on a mild 360?

[Tim_K]

I've got a mildly built 360 (# match motor) in my 1979 Dodge Aspen R/T.

3730 lbs with me and tools and spare tire, 1/4 tank of gas.
Comp Cams Xtreme Energy 274 cam
I ported the heads, but kept the stock 1.88" intakes because I was cheap. It has new 340 springs. 7.70 measured compression, 150 psi on a compression test.
LD-340 with an 850 TQ
Headers and Flowmasters
Non-lockup 727, 2500 stall 340 converter
8-1/4" axle, 3.90 Sure-Grip.
Orange box electronic ignition.

The car's best time so far is 14.57 @ 93.3, shifting at 5500. Higher shift points are no faster.

My goal for next year is to run in the 13's at 100+ mph, even on bad air days. So I think good air days should be about 13.7-8 at 101-102. Faster is always better!

To do this, I could:

Port heads and install 2.02's
Higher compression pistons with valve reliefs
Lighten car (I may get a little weight out of it anyhow, to maybe 3650 or so by adding fiberglass bumpers if they are available (?) )
UltraDyne cam
Would a Holley 750 mechanical secondary double pumper make more power? I don't think it would.

Or, just put in a nitrous kit. The calculators at www.prestage.com say I need another 60 RWHP to reach the 100 mph mark. So that might be a 75 or 100 shot. I wonder if a stock 130,000 mile 360 piston can handle that much, or should I just get another early casting 360 and build it instead? Forged pistons will cost too much, and I've heard a lot about Hypereutectics shattering, so what pistons will take it? And what buildup route to 100+ mph would you suggest?

And will the 8-1/4" handle it safely?

[gsmopar]

You should be safe up to a 125 hp shot. Spend a little $$ on a good electric fuel pump. A fuel pressure switch is also a good insurance for a #'s matching block.

Here is a little idea of what you can expect. We bottled my friends '70 Olds 442. It ran a 14.8 no nitrous at 5200ft elevation. Running a 175 shot in just 3rd gear put the car into the high 13's. Running it in 2nd and 3rd yielded a low 13 almost 12. Running through all 3 gears with slicks it hit a best et of 12.8. The 125 shot through all gears was a low 13, but not as much fun

The dangerous part of nitrous is the giant grin it puts on your face. It's so easy to make the car fast peple keep increasing the jet sizes until they break something. I'd suggest a NOS Power Shot (non adjustable 125hp), or Super Power Shot (adjustable from 125 to 175) if you plan to upgrade to forged pistons later. Both kits are small enough that you can't get too crazy. I'm sure other companys are good too, but I only have experience with NOS.

Good luck!

Greg

[Tim_K]

If I use a nitrous system, I'll rebuild another short block. I'm not going to take a chance on ruining the numbers matching engine.

Since the air cleaner clearance to the hood is already tight, I think I'll need to use a direct port system (tubes to each port on the intake manifold), because any raising of the carburetor with a plate system won't clear the hood and I'm not going to use a hood scoop. Since I already have an aluminum intake, it'll be easier to fabricate aluminum blocks and have them welded on.

[1972roadrunner]

or you could get a NOS fogger system...

it'd probably be a little more work, but i think you'd be happy in the long run if your motor can take it.

gsmopar - is a fogger system dry, or wet? i know the plate under the carb is wet, so fogger is dry, right? dry is harder on the pistons etc, right?

just somthin to chew on...

good luck!

[Mr.Mopar]

Get the cheaper Sniper kit. It is adjustable from 100 - 150 hp and the plate is only 1/2" thick. You will save yourself lots of trouble and grief just using the kit. I run 125 hp on my 340 and it really works good. Went from 14.3 to 12.35 with slicks. Too much fun! Didn't hurt a thing either. Never blew up anything and if you want to be safe run the 100 hp jets, its still gonna put you in the 13's.

[gsmopar]

The Fogger is Wet. Most of the Carburetor kits are wet. Dry Kits use the Sensors on the newer computer controlled cars to richen the fuel mixture once the Nitrous is added. I think the really small kits like the "Sneaky Pete" are dry, but you're only looking at a .10 of a second improvment. Sneaky Pete

The Sportsman Fogger is a direct port kit that's adjustable from 50 - 250 hp. You won't have any hood clearance problems, nor will you need to weld up an intake. Honestly, its an overkill for what you're looking for, and it's big $$$ (Summit price of $639.95 to be exact).

Whatever you decide I'm sure you'll have a blast!

Later,

Greg

[451Mopar]

With a small shot of nitrous (100 HP and under) you just want a good fuel system and ignition system. The stock engine should be able to handle it if it is in decent condition.

With a small block, larger HP shots can cause the head gaskets to blow out because there is only 4 bolts around each cylinder.

If you have seen the new PHR magazine with the Indy built small block, they used the race block which has the extra cylinder head bolts, and the Indy heads appear to use them too.

[Tim_K]

As I said earlier in this topic, THERE'S NO ROOM FOR A PLATE SYSTEM. The air cleaner can not even go up 1/4", much less 1/2". Even like it is, there are paint rub marks from the air cleaner on the underside of the hood.

Are there any air cleaners available to drop the filter element down around the carburetor an inch or so? I have a modified 440-4 air cleaner on my TQ right now. An 11" or 14" open element would be nice, but NO CHROME air cleaners!

Besides, I like the idea of the direct port system being able to totally control the nitrous/fuel mix going to each cylinder, even though my LD-340 doesn't appear to have any significant problems in the fuel/air distribution.

[Mr.Mopar]

Try Edelbrock or Comp Cams, they have some polymer air cleaners that may work for you, otherwise I'm afraid its open element time for you. Maybe Mopar Performance's catalogue has something in a factory type 340 air cleaner. TD performance products definatley has a drop base air cleaner that would work. Or you could spend $700.00 on the fogger system, sure would look pretty and might impress all the girls.

[1972roadrunner]

look in PAW, they have a bit of NOS foggers...

heres some others
http://www.summitracing.com/ part #: NOS-02622 - NOS-05088
the first one goes above the manifold, and the second one goes below and requires the intake to be off the motor for install

good luck and enjoy!

i kinda feel sorry for your wallet though, it'll take a hell uv a beating...

[Tim_K]

After some research and looking at the car, I'll have to use a plate system. It'll do just as well, I guess, and be $200 cheaper in the process.

[wedge440]

Here is what your looking for...

(taken from summits web site)

Pack a concealed weapon under your hood.

For V8 engines with Holley square bore carburetors, 75 to 150 HP, 10 lb. bottle, hidden, Top Shot nitrous oxide system

Your enemies will never know what hit them! This Top Shot concealable nitrous oxide system mounts easily inside your air cleaner and delivers between 75 to 150 HP gains. It simply slips over the carburetor/air cleaner stud--without having to remove the carb. The kit comes complete with an unfilled nitrous bottle, nitrous and fuel solenoids, filters, fittings, jets, switches, aircraft-quality steel braided hose, and all other necessary hardware for a complete installation.


Kit sells for $469
Joe

[PRO]

Here are some N2O rules,cast pistons can handle 150hp shot,hypereutectics can handle 200hp,and forged anywhere from 250 to 600 depending on manufacturer.A 130K motor cant handle any at least not for very long,it will come apart most likely a rod brg will fail so rebuild it 1 st. N.O.S. make an injector for N2O and fuel that hangs on your air cleaner stud and doesnt raise your carb hiegth and is cool because its concealed.Dont be afraid of hypereutectics as most failures are due to so called engine builders that cant read the instructions for piston to wall clearance and ring end gap.Be sure to run a decent electric fuel pump(100gph min on mild sb)with a 150hp shot or less and ALWAYS run a hobbs switch,it cuts off the ground circuit of both solenoids when fuel pressure drops below 3.5psi thereby turning off the system long before it goes lean.You'll have to retard the timing some to take full advantage of N2O,usually 2* for every 50hp,so at 150 youll be 6* retarded which could mean as little as 4* initial which makes it hard to drive so you may want a custom curved dist just for N2O or an MSD ign with a timing retard thats activated when the bottle is on.14.57 is a pretty respectable for your present combo...kudos,your TQ isnt a good 60ft carb,youll find a better launch with a 700-750 holley vac sec,(670 avenger would be perfect) and the 8.25 is a c clip piece which ought to scare the hell out of you and anybody next to you,when the c clip fails the whole axle and wheel come out of the housing.....wheeeee! get a c clip eliminator kit or find an 8.75,have fun.......PRO......

[Tim_K]

Thaks, PRO, that was a very informative post. I forgot to mention that this engine was rebearinged (tri-metal full groove) and reringed (moly) when it had 115,000 miles on it. It is a factory E58 motor, so it had very little bore wear.

It still has stock rod bolts, stock main bolts, and the original pistons in it. I was thinking of either a 100 or maybe a 125 shot. No more than that unless I build another motor with good parts in it.

The 8.25 axle does make me nervous every time I launch it off the line because of the C-clips, but I know several people using them in 13 and 14 second B-bodies who claim they never had a problem. I know someone who has a '69 B-body 8-3/4" which will almost bolt in. I just need to redrill the holes and move my front leaf spring mounts out about 3/8" each.

I was thinking of trying a 750 mechanical secondary Holley double pump.

It's nice to know that at least one other person thinks my combination is running as good as it can right now. I took it to the track last night, and tried a high rpm run, shifting at about 5800-5900. It ran 14.87 @ 91. 2.11 60 foot. I knew that was too high to shift, and confirmed it. Then it rained, and I didn't get to make any normal rpm passes.

[fastback340]

your combo looks pretty good to me. I would change a few things. mainley the carb. The thermoquad is good but how far can you get with it. parts are getting hard to find so I'd make a swap to a holley 3310 750 vac sec. or a 770 street avenger. If money allows maybe a 650 or 750 speed demon (ask cuda66273 about em). Id stay away from a Doubble pumper on a heavy street car.The nos kit that fits in the aircleaner sound like the way to go with your hood problems and if you can get that 8-3/4 you can go with more gear. maybe some 4.30s to get you moving or 4.10s if you gonna keep juicing it. Ofcoarse with the 4.30s then the doubble pumper 700-750cfm amybe the way to go.

[Tim_K]

Okay, we're getting this thing fairly well sorted out. Here's all I need now:

1. A quality (Dynamic) 3000 stall converter
2. New 6 leaf springs. Mine have a reverse arch worn into their front sections. Rear of car just DROPS down on the launch and the 1-2 shift!
3. Polyurethane front suspension rebuild kit
4. Gear Vendors OD unit.
5. Fiberglass bumpers to lose about 100 pounds.
6. Holley 750
7. A way to pay for it all.

Anyone got about 5 grand they want to donate to a worthy cause? Christmas is coming, 'tis better to give than to receive, and there must be a way to make it into a nice tax deduction.

Come and see the '79 Aspen R/T in question here at:

www.angelfire.com/pa5/timk225

[DEMON SIZZLER]

A properly jetted/set-up T.Q. will work fine on your engine combo;
I personally tuned/jetted a bracket racer's 340 with a T.Q. and he used a NOS Cheater(125 hp shot)and the car picked up 1.04 sec
in the 1/8 mi and 5 mph.

There are many parts available for 1972-up T.Q.'S (new):

rebuild kits,
new brass or neoprene floats,
new choke pull-offs,
new accelerator pump check valves,
new primary jets(.090"-.105" id's)
new 2ndary jets(.100"-.189" id's)
new accelerator pump springs,
new metering rod piston springs,
new vacuum port pipe fittings,
new linkage clips,
new 22 degree idle mix screws,
new accelerator "s" links,
new metering rod cover plate screws,
new accelerator pump arm piviot screws,
new 800 or 850 cfm bowls(mid sections),
new main well passage plugs,
any individual gasket,
new pull-off front linkage washer,
and any part that is included in the kits-available individually.

Also, rebuild kits/choke pull-offs/floats for any Competition Series
or SuperQuad carbs.
DAVID.

[Tim_K]

Demon Sizzler, is this your parts list, or do you have a more detailed one? I wouldn't mind building up my TQ some more, but parts are hard to come by.

Here's how my TQ is right now:

All choke and secondary lockout linkage (and choke plate) is removed. The secondaries are zip-tied to be on whenever I want them.
Air door is 3-1/2 turns, I think. It's been a while. The vacuum can is still connected.
Metering rod screw is (I think) 1-1/2 turns up from bottomed out. Stock setting.

.104 primary jets
.145 secondary jets

Carb runs good, but sucks gas at about 10-11 mpg. The way I drive it (and with 3.90 gears), I can't say that's a surprise!

If you have a complete item by item parts list, let me know, and maybe you can email it to me or use the post office. I think there's a few things on that list I could definitely use. Thanks.

[Mr.Mopar]

Tim, I think that your gas guzzling problem may have something to do with the .104 primary jets. My 9811 TQ had .97 factory jets and got great mileage with my 3.91 gears. The Mopar Performance book also states that a .095 jet would even work better for performance. I have learned a lot from Demonsizzler and reading tons of info on the TQ. Thats my .02 cents worth. I wish I could just tweak the TQ as good as he can. Send it to him, you can't go wrong, his work is proven.

[DEMON SIZZLER]

Thanks MRMOPAR! I'm glad that I was helpful to you.

Timk, the .104 " jets are rather large but if the carb is a 9000 series oem carb, then that would explain why the jetting is so large; the bleeds are a much larger id for the idle circuits after the 6000 series carbs and this will lean out the idle circuits quite a bit. As for the above mentioned parts, that is a complete list of individual parts, DAVID.

[Tim_K]

I forgot to mention that this is a 6322S carburetor. (1973 440 carb.)

It had #98 and #125 jets in it stock. I richened it up to #98/#137's, and last winter I had a lean surge problem. In tempertures of 50 degrees and below, even with the engine fully warmed up, under WOT acceleration it would get some violent backfires at the top of each gear. Putting in the #104/#145 jets fixed it.

[1972roadrunner]

that would definently be your gas footage problem... (note, footage, not mileage ) that sure is a lot of fuel though. i don't think you'll have to worry about not having enuff fuel with NOS... i still recommend running a second and seperate fuel line for the NOS though, better safe than sorry!

[Tim_K]

I don't think reducing the jet size will affect gas mileage all that much, but I do worry about going too lean and getting that lean surge back. It was nasty the first time.

[cuda66273]

Well...I've been following this post for awhile now and I guess i'll add my 2 cents worth here..

If you want to stay with the TQ i'd send it to Demonsizzler....

If it were my project and it never would be because I just don't believe in cars on drugs, it would have a 650 Speed Demon on it if the cam duration was below 240 @ 50 and a Mighty Demon if it was 240 -260.

I would recommend a Carter M4864 120GPH mecanical pump and Holley electric blue wired with a relay and through the arming switch, plumbed on it's own supply line from the tank.

I would install a BG 5000 series filter between the tank and all pumps, this is where we drill and tap the BG 5000 to make it a single in/dual out filter system. It will need to fed by a -10 line from the tank or cell, we drill the tank and install a -10 bulkhead into the stock tanks or preferrably a cell. When we drill a tank we remove it, fill it with water and drill with a 12 volt Makita...saves cinging the little bit of hair I have left...

A Rush or K&N 3X14 filter or a 2X14 with the filter top is a must. Careful jetting and a retard box are essential as well as the kill switch from the pressure side of the fuel system.

What your going to end up with is a car that's very difficult to dial and expensive to run, if you start making a few rounds you'll need an extra bottle and a heater to keep it at an even temp.

You need to study up on plug reading techniques and watch for your piston tops transferring themselves to the spark plugs.

May I also suggest that you not use your No2 for the burnout...the oil makes the box greasey and it P/O the other guys your racing with.

Good luck

[dirty dan]

Originally posted by cuda66273
Well...I've been following this post for awhile now and I guess i'll add my 2 cents worth here.
May I also suggest that you not use your No2 for the burnout...the oil makes the box greasey and it P/O the other guys your racing with.
Good luck

I would have to second that idea.