Topic: 2.5 head work

[huntingbuck101]

I plan on putting in my new motor in the next few days. well not a new motor but it has only 5000 miles on it.
any how I was just going to install it but now a guy a work is trying to talk me into letting him port match and smooth out the ports so theres no sharp bends or ridges. I've seen his work and it looks nice and his camaro had 618 hp at the motor so he seems to know what he is doing. Would the 2.5  see a noticeable hp increase? If done right about how much?  I just want to weight leaving stock and the possibility of having something go wrong
along with the cost of a new head and valve gasket.

[chardrc]

im no excpert.. but if it was me i would get it done.. it will add to any intake or exhaust mod you have and is a all around good thing.

[chrisfranklin]

I plan on putting in my new motor in the next few days. well not a new motor but it has only 5000 miles on it.
any how I was just going to install it but now a guy a work is trying to talk me into letting him port match and smooth out the ports so theres no sharp bends or ridges. I've seen his work and it looks nice and his camaro had 618 hp at the motor so he seems to know what he is doing. Would the 2.5  see a noticeable hp increase? If done right about how much?  I just want to weight leaving stock and the possibility of having something go wrong
along with the cost of a new head and valve gasket.

Probably would call for a MAP Adjuster upgrade though, so you'd get the right Air/Fuel Mix along with the better flow. 

[wrangler387]

go for it, if all he is doing is just cleaning up the stock casting marks and other manufacturing edges then i would. I just did this to my spare head... one day i'll put it on. The valve guide bosses could definately be ground down some to promote flow. The exhaust one is a huge wall imo.

[jwrape]

Probably would call for a MAP Adjuster upgrade though, so you'd get the right Air/Fuel Mix along with the better flow. 

There shouldn't be any need for this unless you are putting more fuel into the motor. The only thing this is gonna do is increase the flow by taking out the rough edges. It will just improve mileage and performance if anything and will help if you do any intake or exhaust work. But if it was to change its Air/Fuel mixture, the 2.5L already runs rich from the factory anyways so you might just fix that problem by porting and polishing.
Ask YJmechanic about it. He has built a 200hp 2.5L a couple years back and his is doing excellent. You might wanna add a cam to your rebuild too. You will get a lot of extra power out of a Stage 2 Mopar cam(if you can find one). I bought two online about a year ago, one for my rebuild and one for my Dad's. They are supposed to be a GREAT upgrade.
You can also get a NEW one here.

http://www.hescosc.com/shop.asp?action=details&inventoryID=42889&catId=

[Tall Boy]

YJ mechanics rig sound allright to me. i remember him posting on it about six months ago or so. i think it cost him around $1500 for parts and labor for a DIY job if I remember correctly. Bored over pistons, new cam, new chain, bigger valves etc..
 One day if I don't do a swap, I will be looking that information up on what he did. I still like the fact that the 4 cylinder does not take up alot of space in the engine compartment. I wonder what liter displacement that put his motor at , from a 2.5? 2.9L?

[chrisfranklin]

Probably would call for a MAP Adjuster upgrade though, so you'd get the right Air/Fuel Mix along with the better flow. 

There shouldn't be any need for this unless you are putting more fuel into the motor. The only thing this is gonna do is increase the flow by taking out the rough edges. It will just improve mileage and performance if anything and will help if you do any intake or exhaust work. But if it was to change its Air/Fuel mixture, the 2.5L already runs rich from the factory anyways so you might just fix that problem by porting and polishing.
Ask YJmechanic about it. He has built a 200hp 2.5L a couple years back and his is doing excellent. ]

Without controlled tests this is speculation (and I'll include myself in this speculator category  ).  But, more air flow needs more fuel flow to maintain the same ratio.  There's that little problem with Jeep using the MAP and IAT sensors to determine fuel flow instead of MAF, at least on the 2.5s in the YJ and TJ.  What porting and polishing on a 2.5L will do to Manifold pressure and readings from the MAP is a question seeking an answer.  I speculate that the engine would take in more air as a result of the porting/polishing, but manifold pressue would stay constant (or decline as a result of the greater airflow aft of the MAP sensor?) meaning fuel flow would stay constant (or decline?) despite the air flow increase to the cylinders.  The only way to restore the air/fuel ratio would seem to be a MAP adjuster. 

But, if it turns out the MAP Adjuster is unnecessary for internal mods, I'd be interested in getting a porting and polishing job done down at my favorite shop in Orange County.   

Note: I take it YJ mechanic is not using a MAP Adjuster on his 200hp 2.5L, right?

[damon54]

  What is a good machine shop in Orange County?

[chrisfranklin]

  What is a good machine shop in Orange County?

Sultze's Autmotive.  Its a little shop, but they do custom engine work.