Cost effective

[r55nls2002]

Truck...
Stock... 1998 Ranger
short cab, short bed
Rwd, manual trans
2.5L, 270K miles

Hello all!

My predicament is..... Bad rod bearing on #2. Since I am going to rebuild the engine I was wondering the most cost effective way to add about 30hp. I would like to have little more power for passing and going up hills. I plan on shaving the head and getting it a nice valve job. I am also going to clean up the ports if need be and work the intact and exhaust manifolds so everything lines up as it is suppose to. I will change out the gears in the rear end or the rear end itself, but that a project for another time.

I am looking to accomplish this as cheaply as possible. Any tips, tricks, links or just point in the right direction. I would greatly appreciated

Randy-.

 

[scotts90ranger]

If you have a die grinder go at the head, it's the biggest restriction on these engines and the cheapest mod you can do if you have the tools and already have it apart. I don't know if you've ground on a head before but the carbide bits are nice, and put a pressure regulator right before the die grinder to give you control that way instead of throttling the valve on the grinder. Your head is different than mine but there was a LOT of extra material in mine that was obstructing flow on both the intake and exhaust, although the intake side will make the most difference. Don't gasket match as the gaskets on these don't generally meet up well on either side, but smooth it out so it looks better. On my intake manifold I smoothed the bumps in the intake manifold for the fuel injectors.

 

[Mikel89us]

Make sure if you do port work to leave a semi rough surface anywhere liquids(fuel) flows. You can polish anything with dry flow. The only real way to hai power is head work. And any cam you might change first is expensive, and 2nd will require a tuner to adjust for the different profile. You also need bigger injectors to make any more power. The stock 2.5 injectors are 15#, and are only good for aprox 115 hp, stock is 110. What ever you do, don't buy some "tuning chip" that claims a hp gain, they are all bogus. Milling the head will raise compression and give you some good boost in tq, but only a few ft lbs. Maybe a hp or two.

 

[4b316]

I also would change over to a tube header from a 95-97.Might not make any more hp but will drop about 25lbs off the front.Some of the guys on here are saying to change over to early rockers to change rocker ratio,I havent done that so i can't recommend..

 

[Mikel89us]

Changing rockers does not change ratio. I've explained this many times, the lifter boss position in the head is closer on the 2.5 to the cam than on the 2.3, that is what causes the ratio change. The thing you change by putting the old rockers in is the roller position, and its not a good change. The old rockers also have a wide gap for the valve and the 2.5 uses a smaller valve stem. Doing this will only cause problems.

The tube header hurts performance.the 8lbs you lose isn't worth the couple hp you lose. The 2.5 cast exhaust manifold is the best stock manifold. However, you can free up a couple hp by putting a less restrictive exhaust system on it, but if you have to have a catalytic converter in your state or county, you are looking at big bucks for this.

 

[r55nls2002]

I do have the necessary tools to go at the head with. Its a perk of having an retired ASE master mechanic for a father. I have done this sort of thing before on heads but is nice to have a reference. Do any you guys have a link?
A descent cat back could be in the cards because the stock exhaust is getting kind of rotten.
Thank you so far!

 

[scotts90ranger]

I just went for it, the ports as stock are UGLY and restrictive, very lazy looking at least on my '85 head , here's a before pic:



Here's the setup I used:



Here's one of the "after" pics I think:



These heads are known for having worse ports on the intake than exhaust, so spend more time on that side. If you look carefully you can see I smoothed out that lump, and the valve guide post thing, and spent more time and effort on the outside of the bend radius than the inside.

 

[r55nls2002]

Thanks for the pictures! The Volvo b2300 motors also have same problem when it comes to air flow and the head.
I also ran across an article talking about using rocker arms off a 98-2000 head and a roller cam from the previous gen engine, as a good budget mod. Will this apply to my 2.5 or the just the older 2.3's?

 

[Mikel89us]

The 2.5 has the head with the shorter rockers and moved lifter bosses, as I have said, putting 2.3 rockers on a 2.5 is useless, and 2.5 rockers in a 2.3 head is useless. The rockers dont change ratio like a pushrod motor. Teh relationship between the cam centerlive, valve stem and lifter boss makes the change..

Also, the cams are almost identical, and there is no gain in power by swapping one to the other.

 

[Mikel89us]

And in case you question my knowledge, it comes from talking with an engineer, who has been building 2.3's/2.5's for almost 30 years. He has dynoed just about any combination of stock components you can think of. All heads, all blocks, all intakes, and all exhausts. He does computer modeling of most of his parts, and has even designed his own cam grinds for many builds. Also currently daily driving an 86 svo that is compound supercharged/turboed, putting down 528hp and 560ft lbs, and still getting 25mpg.

 

[r55nls2002]

For the sake of an internet forum argument..... Obviously increasing the length of a push rod will open the valve farther equaling more hp. If you change the shape of the rocker arm this could theoretically do the same thing. Does this apply to my application??? I don't know. If it nets me another 2-4 hp then that is 2-4 more hp closer to my goal. The best thing is that it will only cost me $20 and 40 minutes at the pick and pull. I have read a couple things on the internet about this and where there is smoke... That being said the internet is the internet, but generally if you can weed through the BS sometimes you can find a nugget of truth in it.

 

[Mikel89us]

No sir, putting a longer pushrod in a motor does NOT open the valve farther. The pushrod is merely a link between the rocker and cam lobe. The rocker arm ratio and cam lobe height are the only two things that can change valve lift. Rocker arm ratio is directly related to the distance between three points, pivot(lifter on 2.3's, rocker bearing on pushrod motor), the valve stem, and the cam contact(or pushrod point on pushrod motor).

In the pushrod motors, you can change rockers to change the ratio, because its very easy to move one of the points, the pushrod. A higher ratio rocker will have the pushrod closer to the pivot point, causing more lift with the same cam lobe.

This is not achievable with the 2.3 because you cannot move the cam contact point, as the cam is set in one place in relation to the valve. The later motors have a higher ratio because they changed the lifter boss location, moved it closer to the cam. They then have to use a shorter rocker because the distance between the lifter and valve is now shorter. The difference in the rocker is only to make up for the change in the pivot point. This is achievable with the old motors if you sleeve and offset bore the lifter boss, this is very expensive and inconvenient, because the rocker from the newer motor will not fit over the tip of the old valves.

The geometry isn't right any way you try to scramble it, hard facts and math disprove the radical theory that the rocker changes the ratio on a 2.3.

 

[r55nls2002]

Copy. Thanks for braking that down. So that basically rules out the rocker arm swap and getting any extra horse from another cam off a 2.3. So I am just left with milling the head and cleaning up the ports a bit and calling it a day.

Anything else I should address while the engine is tore down?

 

[Mikel89us]

Make sure the cylinders look good. When they get too worn out the pistons will start to slap and can cause major issues.