clayton3854

so im gonna be putting a new 4.0 in my jeep before winter and im looking to make some modest upgrades to the new to me engine before i put it in, i know ill be replacing almost every seal and gasket but what other upgrades will give me the best bang for my buck and not break my wallet? already got upgraded injectors on the way, already got a cowl cold air intake. im not very familair with engine work so any thoughts ideas parts would be great!! thanks everyone

arorton

I haven't really done anything myself, but I've seen people bore the throttle body to 62-63mm, not sure of the effectiveness. And Also throttle body spacers, and maybe spark plugs? I'm not sure of much else that's somewhat "bolt-on".. and I also have no idea if spark plugs make much or any difference lol.. just the first couple things that came to my mind.

I Leak Oil

Cam, roller rockers if u can afford them. 99+ intake. Bored tb. And enjoy

I Leak Oil

Never......ever......ever recommend tb spacers on a 4.0 again please

clayton3854

yea im gonna bore my tb and just changed my spark plugs over the summer

i have a cowl cold air intake so im not looking to run a tb spacer anyways as iv heard if you run both you cant shut the hood flush

I Leak Oil

Clearance isn't what im talking about. They..........do........not.......do.............. .....................ANYTHING

clayton3854

iv heard that too, but like i said considering the clearance issues i nvr further looked into it as i new i wasnt gonna be buying one.

I Leak Oil

Good

I Leak Oil

I gave i the big ones. Besides machine shop work there isn't much. I mean spark upgrades.

xjshorty21

i was young and dumb and bought one and then decided it was better to get kicked in the pants then believe it does something so turn around and sold it making most of my money back... but always hang my head down thinking i bought that junk

but idk if your somewhere its hot but a upgraded water pump may be a idea, its not speed but something important. get some bombproof motor mounts , but definely just , 99 intake and machine shop.

5-90

Cam, head, and exhaust are good places to start.

Opening up valve timing allows greater airflow into the engine, opening up the exhaust a bit helps get the air out (the pipes are about the right size - use a high-flow catalytic converter and a high-flow muffler to open that up.)

However, the primary restriction in the entire system is in the cylinder head - intake and exhaust ports. If you're not going to put the head on a flowbench, you'll just want to clean up the surfaces without changing the shape or size! It's painfully easy to screw up your work without working in small intervals and keeping track of where you are...

I don't understand the utility of throttle body spacers - they sound to me like an outgrowth of the old carburettor base heat shields - which weren't to do anything to the intake proper, but to keep fuel from boiling out of the float bowls.

Oversizing the throttle body bore isn't a performance adder in se, the OEM throttle body is capable of allowing enough flow for even mid-range stroker engines. The perception that the bored TB is a "power adder" comes from the fact that it does increase part-throttle response (more rapid changes in flow area at part throttle,) which can feel like an increase in power - however, it is not.

Other things that can be done?
- Finer/more injector spray nozzles. This will more efficiently atomise the fuel as it is sprayed in, which increases combustion efficiency. It's not necessary to go with injectors rated for higher flow rates - just get something with a finer spray droplet size.
- Cold Air Intake (CAI) kit - which allows a denser air charge, which allows more fuel to be burned, which allows more power to be made.

(Come to chew on it, the idea of a throttle body spacer may come from trying to refine Helmholtz resonance tuning. But, it's not enough of a chance to make any different whatever - considering the "native crankshaft speed" at which we make peak torque, you'll end up needing intake runners a good 30-36" long before you can even get into Helmholtz resonance tuning in the first place. So, a 1" spacer won't matter - and it's in the wrong place anyhow, since it doesn't move the back wall of the plenum a whit...)

GRANDLICH

When you say ungraded injectures you mean the 4 hole ones?

5-90

Correct.

Gasoline doesn't burn very well unless it's been vapourised (liquid gasoline doesn't burn, gasoline vapours are borderline explosive!) so you want the droplets to be as fine as possible.

Carburettors required some room to allow the relatively coarse droplets of fuel to finish evapourating before they were compressed. However, as fuel delivery happened closer to the cylinder, a finer division of the liquid fuel was necessary.

This was assisted greatly by the fact that most port fuel injection setups run a head pressure of 30-50psig - while a carburettor relied on differential pressure below atmospheric. A higher pressure forced through an orifice can result in finer division of the liquid - and being able to use a smaller orifice to get similar fuel delivery will also allow finer division of the liquic.

The "four-hole" injectors that Ford used were taking this a bit farther - instead of a single port to spray fuel, they used four ports that were roughly the same flow area (altogether) as a single port would have been. Smaller ports = smaller droplets = faster evapouration.

(I believe it is this property of gasoline that is proving a handicap in coming up with a working DFI setup. This would be far easier using propane or CNG - but either of those fuels has about half of the energy content per unit mass than gasoline, and the infrastructure for distribution isn't there yet.)

arorton

Sorry, clearly I put my other statement in the wrong place. I meant to say bore it if anything, and then say some people put spacers, but I don't know of their effectiveness. I have heard some people swear they work and others say the same thing you did. I never claimed to their effectiveness, I've just seen posts about them previously so I thought I'd throw it out there. And yeah I would also have suggested a cam, etc, but the rest of his things were bolt on, so I was trying to come up with anything that was just bolt on. Sorry it appeared I was "recommending it"... I also said I hadn't tried boring it or the spacers so I wasn't positive to the effectiveness of either.

V8XJDavid

Stroke it. Longer stroke will give you more torque and low end power without any other engine mods. If you go with a hotter cam, be sure your intake/exhaust/ignition can deal with it or you are doing more harm than good. If your cam has higher lift and duration than stock, you need better (bigger) valves and having your intake and head ports machined and matched. Also a cam will mess with your vacuum levels.