supercharged 304 build

[brickproof]

as the title suggests i have a amc 304 that i bought with the intention of swapping it into my 1989 jeep wrangler. i chose this engine because it was as far as i know the only v8 that wranglers were ever factory equipped with. so anyways i have the engine completely broken down and awaiting rebuild and as most people do i am looking for ways to gain more power from my engine. so my question is iv seen the kits available on this website for the supercharger and am wondering how i should build my engine to prepare for using the supercharger and getting the most out of the supercharger install (like what machine work should be done, cam choice etc etc). iv seen somewhere before a guy talking about easily achieving 500 horses out of a supercharged amc 304 and am wondering how exactly i should build mine to achieve this because iv never built a engine before. i also know a lot of people will say to just use 360 or 401 but i am set on using the 304 because of the cool factor.
any help is appreciated.

[brickproof]

the engine is out of a 1974 jeep cj5 btw i forgot that part

[jeepsr4ever]

Absolutely possible to get 500hp thats not even 2hp per cube. You will want forged pistons to start with (buy them from us or anyone else). You will want to make sure your stock components are up to par (magnafluxing to check for cracks). You may want stiffer springs to allow the intake valve to stay seated depending on the boost pressure and definately hardened pushrods. Other than that their isnt a whole lot you need to do to the base engine.

[brickproof]

thanks for confirming that! i was a little worried after reading what some people said about the 304. is there a specific cam anyone would recommend using with the supercharger? i would prefer to have a choppy/performance sounding idle but only if it actually benefits the engine. so you would recommend just having the block and heads cleaned and keep the dimensions stock? while the engine is apart should i do anything to improve oiling because i know the amc engines are known for oiling problems. I have so many questions because i have never done anything like this before and want it to be done right so my apologies in advance.

[jeepsr4ever]

No dont do anything to the block except basic engine machining but make sure all the passages are drilled through especially the feeds to the mains from the passenger side. There are some profiles that work better than others you can consult most any camshaft mfgs about that.

[brickproof]

alright sounds like a plan i just have to find a shop to do the work and figure out how much its going to cost and il be making some more progress. heres some pictures of the engine 240241242243244

[brickproof]

would i be able to build this engine and use it in a daily driver?

[jeepsr4ever]

Absolutely

[brickproof]

ok I'm pretty much abandoning the supercharger idea for now because of my budget. now my question is i still want to get to a decent horsepower and torque rating out of my 304 so how do i achieve this without the supercharger? i already plan on boring it out and using pistons out of a chevy 305 and do machining to the heads to allow them to flow better. i still haven't found any cam ideas out there except for the edelbrock performer which would be fine but if at all possible i would love to obtain a little of a choppy idle. so my goal here is to bore it out to about 318 or 327 cubic inches and get as close as i can to 400 horsepower and torque while still being able to drive it on the street. i will hopefully be heading to the machine shop here within the next week so any ideas are greatly appreciated because i have no idea what I'm doing and there isn't much out there on building a 304. iv also seen on youtube someone built a 304 similar to what i want to build and used stainless steel racing valves so theres another idea to increase flow a little.

[jeepsr4ever]

To use 305 pistons you need to remachine the valve reliefs to 18 degrees. The way to make power is through compression.

[brickproof]

ok thanks i found a amc 304 that i liked on this website and they list what they have done to it so this might be a little useful to me http://www.c-dperformance.com/CDP_Engines_Others.html

[tufcj]

I had a 304 built nearly the same (10.5:1 compression, flat tappet cam and torker intake). Ran it in my Jeep when I mud bogged. Spun it to 6500 regularly, lots of guys thought I had a SBC conversion until I raised the hood.

Bob
tufcj

[brickproof]

I had a 304 built nearly the same (10.5:1 compression, flat tappet cam and torker intake). Ran it in my Jeep when I mud bogged. Spun it to 6500 regularly, lots of guys thought I had a SBC conversion until I raised the hood.

Bob
tufcj

any idea the horsepower/torque? could i run that compression on pump gas? how did you get to that compression? sorry about the questions but i have never done anything like this before and only know what iv read online. and i also want the exact same reaction when i raise my hood. that it really the whole reason with building this motor and not a common motor like everyone else.

[tufcj]

Mine was running 350+ HP. I had to run race fuel, it would ping on pump gas, even with the timing backed down (which really hurt HP). To run premium pump gas, you're going to have to keep compression in the 9 to 9.5 range depending on cam specs and dynamic compression ratio. The pistons I ran were forged TRW, I know they aren't made anymore. Google "static and dynamic compression ratios", there are calculators out there. You'll need to know the compression height of the piston you're going to use, the volume of any dish in the piston, as well as the volume of the combustion chamber in the head and cam specs. It all has to work as a team. You see why professional performance engine builders aren't cheap.

I ultimately went to a 360. 1 HP per CU IN is very easy to attain, going past that number is where it starts getting expensive and abusing parts. When I went from bogging to rock crawling, I needed an engine with a much different HP and torque curve. The 304 ended up in a Hornet, my Jeep ended up with a much milder built 360.

Bob
tufcj

[brickproof]

i know making power with the 360 would be loads easier but still want to use the 304. is there a certain route someone can suggest i take in order to reach decent horsepower ratings? i have also heard that forged pistons don't do well in daily drivers...can someone shed some light on that subject as well? i appreciate all the help

[tufcj]

You have to build the engine for the application. There is no "formula", you have to pick parts in a combo that will work together. That's where a professional engine builder will help. A high HP engine will lose some torque, a high torque engine will sacrifice HP. In drag racing, torque makes ET, HP makes MPH.

You need to make any AMC engine breathe. Keep compression around 9-9.5:1, Spend your money on valve/head work. With my 304, 1.94/1.50 valves, a good polish/port, and a cam with about .500 lift really made for a potent combo. Balancing is important for both performance and longevity. Forged pistons work well on the street, but they do require a little more piston/wall clearance, so you may hear some cold "piston slap", and you want to warm up your engine before romping on it. I've been running forged pistons in my AMX 390 for 7+ years with no problems. I built that engine with forged pistons and stainless valves so I could give it a 100 shot of N2O if I wanted to, so far, I haven't seen the need.

Bob
tufcj

[brickproof]

i understand that everything needs to work together and since this is going in my jeep with future plans being maybe 40 inch tires i would sacrifice the horsepower for torque and i will use forged pistons but can the piston slap be prevented? if warming the engine up eliminates it thats fine because i always let my cars warm up plenty and don't ever really plan to romp on it i just want to know the power is there if i ever want to shred some tires or tow something. i plan to keep the jeep on the road 90% of the time. with any luck i will be heading to the machine shop within a week or two *fingers crossed*

[jeepsr4ever]

You should not hear piston slap with any forged piston unless your going with a 2618 material piston. The reason is the 2618 needs more clearance due to the expansion clearance it requires when other types dont need that type of clearance. You run a 2618 piston when your in excess of 800hp and over a 150 shot of NOS or your running 12lbs of boost.

[brickproof]

ok so i know not to use that material when selecting pistons thank you for clueing me in on that. I'm going to start comparing prices for the machine work today when i get a chance.

[brickproof]

iv dropped my engine off at the machine shop with the guy saying he will have a estimate within a week. he pretty much shot down all my ideas, saying to gradually increase my bore instead of going straight to .060 over, he told me to avoid polish/porting heads because it will decrease my torque, and he also said he could have me running a 10 for compression with the right distributor and etc. hopefully this guy knows what he his doing and can actually accomplish what he is saying.

[tufcj]

You won't get the HP numbers you're looking for without port/polish and bigger valves on the heads. I'm not talking radical, just cleaning up the casting flash and smoothing the runners. With factory heads/valves, you might get 1 HP/cu in, maybe a little over 300.

Bob
tufcj

[jeepsr4ever]

You definately dont need to polish. Port work can help but compression and a good cam would be a good start.

[brickproof]

alright well il have to see what he wants to do after he's looked at it and try to convince him into using the bigger valves

[newt]

The power numbers you are looking for (400hp) will be difficult w/ the little 304 (difficult is just another way of saying EXPENSIVE). I think you might be happier with a nice 'normal' performance build and then add a shot of N2O for those rare times when you really need the power. This will most likely be the most cost effective way to hit 400 hp and you'll have a reliable / drivable engine for the 99% of the time you don't need 400 hp.

[brickproof]

i agree with that statement but i would also be fine with only 300 horsepower with hopes of getting that and maybe 400 torque so far i only have a estimated price for labor coming in at a little over a grand