[TheJ]

I have a 93 dodge shadow 2.5l TBI and it recently broke its timing belt. I'm going to replace it with a mopar belt and tensioner and I figured while im in there I might as well do some up grades. I'm thinking of getting a mild cam and wanted to know if I need to get new lifters with it? Also what are your guys' thoughts on an underdrive crank pulley, is it worth it?

Thanks for looking.

Jayson

I just realized that I posted this in the wrong section, is there a way to move it?

 

[Bob Lincoln]

Moved.

It depends on your goals. IMO, upgrading a cam without doing head work to improve breathing is a waste of time. I believe you would want to use new lifters. And underdrive pulleys have the tradeoff of undercharging the battery and providing less power steering assist.

 

[B10alia]

You're not going to gain that much with an underdrive pulley. Keep in mind that a 5% gain on an engine with about 100 horsepower stock is about 5 horsepower. The cam is a bit more work than you would think, too. I would recommend saving your money and getting an adjustable cam pulley. This will allow you to tweak the powerband just like you would be doing with the cam, but without as much work. I had advanced timing on my '95 Spirit and it made a HUGE difference in low-end power (based off the very casual observation of how long the tires squealed when floored). However, compression jumped up enough that I was endangering the headgasket (on the order of 175-180 psi per cylinder). That was one tooth, or 7 degrees, advance. Most cam sprockets go up to about 5 degrees, and you can play with the timing without really having to dig into the engine. All told, you'll spend less money this way, too.
I currently run a K&N filter (helps a little, but the performance gain and dirt flow through the filter is pretty highly debated both here and elsewhere) and a 2.25" exhaust to a Super Turbo (a royal PITA to do on my car, since I DIY'ed it and had no previous experience with exhaust. I believe Dynomax has a couple of pre-fabbed parts for the P-bodies in this size, though). Far and away the biggest jump came from the exhaust; I dropped 2 seconds off my 0-60 and now average over 25mpg mixed.

I agree with Bob on the lack of potential gains without head work from the cam swap. You'll get something, but it is pretty much a waste without at least a port job.

 

[dana44]

You may want to pull the head, this is an interference engine and you may have bent valves, so do a quick belt change and spin it for a compression test first. Another thing you can do is verify each of the valves move and are at the same height after you pull the cam. Don't want to have to do the same job twice this way. Agree with the adjustable cam sprocket over the cam itself, the heads are rather restrictive unless ported, tons of gains with the ported heads. The valves are super shrouded and the exhaust valve is half blocked, sharp edges increase pinging and the likes.

 

[TheJ]

I thought it was a noninterference engine and the belt seemed to break at TDC for cylinder 1. I have a 2" exhaust going to a dynomax 2.25" axle back and a custom cold air intake. I was going to get an adjustable cam sprocket as well as the cam. I think I'll ditch the idea of an underdrive pulley.

Thanks for the info guys.

 

[Bob Lincoln]

The 2.2L and 2.5L 4-cylinders are a non-interference engine.

ALL factory air intakes since the 1970s are "cold air intakes". What some people are installing underhood are actually HOT air intakes, and perform worse.

 

[1991spirites]

Yup what Bob said. The only 2.2 that was interference was the DOHC motor in the TC Maserati.

The only true cold air intake is where it's going to get the air from outside the engine compartment.

 

[TheJ]

It seemed to be a little more peppy after I put the intake on and got about 1 mpg better fuel millage. One reason for the intake was the corragated tube going from the pcm to te intake broke and I couldnt find anything locally to fix it.

 

[Bob Lincoln]

I built a new intake tube recently using ABS plastic from Lowe's, with smooth walls. I was thinking that the laminar air flow might help a little bit with gas mileage or power. It's thicker, too, so the air should be a tiny bit cooler.

It has made zero difference in gas mileage or power.

Someone can probably locate that intake tube for you in a junkyard or parts exchange.

 

[dana44]

Well, don't I sound like the stupid one, thought it was, but that's good news really.

 

[Bob Lincoln]

I was thinking that maybe you got confused with the 2.5L V-6.

 

[B10alia]

An axle back is still hideously restrictive compared to even a catback. As for cold air, I had a setup pulling cold air from the bumper that I used for a while. I scrapped it, but I am still trying to think of a better intake that bypasses the computer and goes straight to a better-flowing airbox. Several people who use these cars as sort of backyard mud toys (i.e. who have no real interest in keeping the car running) have noted that the engine seems more powerful and responsive with no airbox and filter. Makes sense when you consider that they were designed to be cheap to manufacture. Chrysler cut a lot of performance corners on these cars, and I believe that there's a lot of potential in the engines based on the durability that's built into them, especially considering what some of the turbo drag-racing guys do. It just takes a LOT of work to get that potential to come out; there really isn't much that you can drop in or bolt on, especially for a daily driver.

 

[Bob Lincoln]

You do NOT want to bypass the airflow through the computer. The MOSFETs that drive the injectors, ignition, voltage regulator and other heavy current loads are sticking out into that airstream, and cutting off airflow to them will cause them to run much hotter. The Arrhenius equation tells us that the failure rate of semiconductors doubles with every 10 degree C rise in temperature. You need cool air intake to flow past these MOSFETs. It does make a difference.

And removing or installing a less restrictive filter just means dumping grit into the cylinders, scoring the cylinder walls, rings, valves, and crudding up the oil so that the bearings get scratched and worn.

 

[TheJ]

Thanks for the concern Bob, I did read about the airflow through the computer so I put a high speed computer fan where the air usually comes in. I'm running a K&N cone filter so I would think it would be no worse than a drop in. Thanks again for the info guys, I'll take a look at porting the head and figuring out the cam.

 

[Bob Lincoln]

Watch the computer fan, as they are not automotive quality and will fail much earlier. Most of them have cheap sleeve bearings. And make sure the air chute leading to the computer is still in place. If you just put a fan on the front of the computer, it will suck in warmer underhood air.

The cone filter is a hot air intake, and will reduce power and gas mileage - unless you have it mounted somewhere other than underhood.

 

[bamman]

Some good modifications you can do include the PT lifter mod and adding an Omni airbox.

For the PT lifter mod you pretty much get the Mopar Performance lifters for the later 2.4L engines, like the one in the PT Cruiser. You'll need a quantity of two part number P5007440. That will get you 8 lifters total. Then you need two correct sized shims to put in the lifter hole. You'll need a quantity of 16 part number 0945.025.0.20 from Fasteners Inc. What this mod does is quieter operation of the top end since by now your lifters probably make a lot of noise, and these lifters are more resistant to aeration so you can run at 6500 RPM all day long if you wanted. If you are contemplating even changing the lifters, this mod is the best thing you can do.

As for intake, you can upgrade to an Omni Airbox. Many say they flow slightly better than stock. If you choose not to believe that, it also makes your engine bay look slightly better IMO and allows you better access to the throttle cable in the engine bay so you can rev the engine by hand if you want.

 

[TheJ]

Watch the computer fan, as they are not automotive quality and will fail much earlier. Most of them have cheap sleeve bearings. And make sure the air chute leading to the computer is still in place. If you just put a fan on the front of the computer, it will suck in warmer underhood air.

The cone filter is a hot air intake, and will reduce power and gas mileage - unless you have it mounted somewhere other than underhood.

Luckily I can hear the fan from inside the car before I start it and I check it for flow when I do an oil change.

Is there anything worth replacing while I'm doing the timing belt and what is a good brand for the belt and tensioner?

 

[B10alia]

Gates is what I used, you can often get both of them as a "kit" from auto parts stores. You may want to consider doing the water pump, since you have to take that whole side of the engine apart anyways. http://www.allpar.com/fix/timing-belt-22.html The only thing I would recommend against this article is to do as much removal as you can BEFORE you take the mount bolt out. I think you can get all the accessory belts and the compressor without having to take the mount bolt out. I removed the two lower bolts for the mount simply because I didn't have the big sockets to take the cross bolt out, and threaded the belt through the gap there. Then you can put the engine back down, so it's only off the mount for a couple minutes. I feel like this method is safer, too, since if the engine should fall, it will fall more or less back onto the mount bolt-down point, instead of onto the ground.
I take it you found out how dearly you pay to have the little "m" and pentastar on your replacement parts... MP isn't cheap, and with things like belts, well-respected companies like Gates or Dayco will serve just as well-- plus they may actually be the MP part incognito...

 

[John Wood]

I agree, the water pump can easily be swapped out with the timing belt out. You'll have to remove the intermediate shaft sprocket (once the AC bracket is out of the way - if equipped), and then you have all the the small water pump screws completely accessible.

Also check any of the front shaft seals for oil seepage since replacing those requires the timing belt to come off.

 

[Bob Lincoln]

He doesn't have to remove the intermediate shaft sprocket. Much easier to unbolt the entire water pump assembly from the block, separate the pump from the housing, mate up the new pump and bolt it to the block.