4bangerjp.com
General Forums => The Mess Hall => Topic started by: Lu on February 24, 2010, 07:31:40 PM
-
In my quest to greedily squeeze every ounce of power out of humble 4banger I wonder many things. One thing I would like to ask is: What are some different, unorthodox ways of increasing an engines power. Except turbo of course, I've heard of turbo. But seriously, are there any odd or weird ways of freeing up some ponies?
-
I would read the build threads by:
1. YJMecahnic
2. Rob the Plumber
3. St. Chevrolet
4. Sharpxmen
There you have 2 turbos, one supercharger and a naturally aspirated engine build.
-
It's all about the leaf blowers these days :dance:
(http://www.bangshift.com/assets/images/news/2009/Feb/15-21/leaf%20blower%201.jpg)
-
It's all about the leaf blowers these days :dance:
(http://www.bangshift.com/assets/images/news/2009/Feb/15-21/leaf%20blower%201.jpg)
:roflol:
better install them pointing back and inject gas in there - home made jet engines
-
The biggest limitation of the basic 2.5l 4-stroke engine is the relative size dimensions of the stroke, piston diameter, and cylinder volume. Then there is the timing flow of the amount of air and fuel into the cylinder and out. There are some things you can do to make some areas better for performance and operation, but the amount of time and effort will be costly compared to that of swapping in something with a little more gusto already built-in.
-
I will have to go to sears and get me a couple leaf blowers tonight and hook up the extra horsepower up that i have been missing out on :wall:
-
It's all about the leaf blowers these days :dance:
(http://www.bangshift.com/assets/images/news/2009/Feb/15-21/leaf%20blower%201.jpg)
Now THAT's what I call thinking outside the box!!!
-
poor poor jeep
-
Notice thats a Ford 5.0 under the leaf blowers? :yikes:
Go big or go home I guess.... :)
Dave
-
What are some different, unorthodox ways of increasing an engines power. Except turbo of course, I've heard of turbo. But seriously, are there any odd or weird ways of freeing up some ponies?
A few I can think of, excluding forced induction...
Uncommon high-end mods:
- Have the engine blueprinted and balanced. This will eliminate vibration in the engine so it'll run smoother and make more power. The engine will also be able to safely run higher RPM than stock.
- Have the head, intake, and throttle body ported and polished. This raises volumetric efficiency, and as such, power and gas mileage both go up a little.
- Have the cylinders bored .030" over and stroked (larger stroke.) Pistons, rods, rings, and all the other stuff to match. This raises CID while still maintaining the stroke-ratio. The compression ratio will go up as well, meaning you may need to run higher-grade pump gas or better cooling to avoid detonation/pre-ignition. If I remember correctly .030" is about as far as you can overbore on the 2.5L without cutting into the water jackets. Remember, there's no substitute for cubic inches!
- PCM performance re-flash, or a custom tuneable PCM like the Megasquirt. In the case of a tuneable PCM, you'd need to figure out the correct figures for the power curve with your current mods.
Each one of these options will be very expensive (some possibly in the thousands.) All of them together will probably cost you more than your Jeep is worth. You can port and polish the head/intake/throttle body yourself with a dremel tool, but be advised, it is VERY delicate work and VERY easy to screw up.
Somewhat Common mid-range mods:
- Increase the distance between the throttle body and the cylinders. You can increase distance by extending the intake runners, and you can decrease distance by shortening the intake runners. Increasing distance will give you more low-end torque, while decreasing distance should give you a few more horsepower and quicker throttle response. The throttle body spacer is a cheaper way of increasing the distance.
- Bigger injectors and adjusted fuel rail pressure to match. Won't gain you much by itself but it always helps with other mods.
- Larger diameter performance exhaust with a custom-fabbed mandrel-bent 4-2-1 header. I wouldn't go over 1" header runners and 2" exhaust pipe unless you're running forced induction. If you go any larger you probably wouldn't have enough backpressure.
- Regrind performance cam.
- E-Fan swap w/ DC control box. This will free up a few ponies that were already being used.
All of these are good mid-range options. These mods should cost less than or just over $300 each if you do the installation work yourself. The exceptions might be modified intake runners and a custom header.
Very Common cheap/easy mods:
- Swap to a larger throttle body. 4.0L OEM or bored out 62mm, it doesn't really matter. Either one is better than stock.
- Buy or build your own 3" intake (cold air or short ram, doesn't really matter) with a performance air filter.
- Upgrade the ignition system (coil, plugs, wires, distributor, battery.)
- Throttle body spacer -- the cheap way to increase distance between the cylinders and the throttle body.
All of these are relatively cheap and easy. These mods should cost less than or just over $175 each. If you swap to a 4.0L throttle body from a junkyard you can expect to spend $30 max. The PD Screamin' Demon Firepower Ignition kit for a 2.5L costs around $190. You can build a 3" intake with ports for the PCV and charcoal canister runners for around $60 including the filter, and you can buy a 3" intake for around $150 including the filter.
If you were to perform all of these mods, I'd bet you could squeeze 200-250 hp and 250-300 lb/torque out of the 2.5L. This is why it's not worth it. You could spend a fraction of the amount needed for all of those mods and swap in a bigger engine that already has more power to begin with.
-
If I remember correctly .030" is about as far as you can overbore on the 2.5L without cutting into the water jackets. Remember, there's no substitute for cubic inches![/li][/list]
I don't know how this 30 and over thing is staying in everyone's minds. My motor is 60 over and obviously it didn't hit a water jacket. If over 30 hits the jacket then even 30 wouldn't be safe to do. For that matter if 30 was max, I be afraid to touch the block at all. My motor turned out fine and I have had no problems with heat or anything else. And by the way, nice to here other people are trying this buildup. Let me know how you turn out.
i don't have any experience with this just throwing some quotes up there. the not over .30 over thing sounds like iron duke territory where every one is saying its to weak of a casting to touch... but then again i have no real knowledge of the 2.5l block
-
i don't have any experience with this just throwing some quotes up there. the not over .30 over thing sounds like iron duke territory where every one is saying its to weak of a casting to touch... but then again i have no real knowledge of the 2.5l block
i think 20 and 40 over are stage 1 and 2 for the 4 banger, can't remember exactly but i'll try to find it and post back if I do
EDIT: i found them in 20, 30, 40 and 60 over for 83-95 AMC 2.5L, so my guess is 20/40/60 for stage 1/2/3 repair (i am talking of 0.020 and so on)
-
I wanted to go .060 on my engine, but when the block was sonic checked
there was not enough meat in two of the bores to handle it so we went 40...
We might have gotten away with it, but my engine guy said it was likely I'd
have hot spots in the water jacket from being too thin.
Dave
-
i don't have any experience with this just throwing some quotes up there. the not over .30 over thing sounds like iron duke territory where every one is saying its to weak of a casting to touch... but then again i have no real knowledge of the 2.5l block
i think 20 and 40 over are stage 1 and 2 for the 4 banger, can't remember exactly but i'll try to find it and post back if I do
EDIT: i found them in 20, 30, 40 and 60 over for 83-95 AMC 2.5L, so my guess is 20/40/60 for stage 1/2/3 repair (i am talking of 0.020 and so on)
I didn't know for sure if you could go to .060. I just knew .030 was safe.
I wanted to go .060 on my engine, but when the block was sonic checked
there was not enough meat in two of the bores to handle it so we went 40...
We might have gotten away with it, but my engine guy said it was likely I'd
have hot spots in the water jacket from being too thin.
Dave
Maybe your engine was already rebuilt once before and already bored over a little to smooth out the cylinder walls? That's all I can think of, at any rate. Still, .040" over is not a bad overbore :biggrin:
-
some numbers, starting with stock 3.875 bore x 3.1875 stroke
cid for stock, 20, 40, 60 thou over in this order
150.3639
151.9200
153.4842
155.0563
1, 2 and 3% increase in displacement
-
Nope all 250K miles were put on her by me... And the cylinders only had about .003 ridge in them.
My engine guy told me Mopar since about 1988 has had a lot of the base castings done overseas or Mexico.
Thier mold quality control is pretty loose. He's pulled down motors that were weeping antifreeze through the
cylinder wall down low between cyl 2&3. NO cracks, or other damage, it had really small micro perforations through the iron.
When he builds a 318 V8 engine he said it usually takes about 4 blocks to find a
good one.
Also my target redline was 7000, and I'm at about 11:1 compression so we had to be conservative
on the bore given the heat I was going to be generating at the upper end, and I planned on pump
gas which means a pretty high burn temp.
Its all a house of cards... :)
Oh, and there are "Iron Duke" castings which will take a .080 rebore and make 300HP.... Mostly Pontiac.
You oughta see what they do when things go wrong....
Dave
-
Oh, and there are "Iron Duke" castings which will take a .080 rebore and make 300HP.... Mostly Pontiac.
You oughta see what they do when things go wrong....
ya but that with the super duty duty block that they made for racing and was never in a production vehicle? thats what i was finding in my search before. sounded cool. they even had a dual overhead cam head kit for it...
-
The super duty block was in some Pontiac street cars, it was also a Marine part number.
I work on a Midget and the other guys we race against several have the Pontiac engines,
some super duty real race blocks but some are stock engines from the old grandma grocery getters.... :)
The voodoo is which engine plant the block comes from, I'll have to try and get the block id info
because that would be handy for the old jeep owners to know... If your gonna buiold a motor go big ! :)
Dave