3.2 cams in a 3.0 for better low end torque?

[jimtash]

Just built a 3.0 with ported heads and am losing a little low end and gaining it up top. I'd like to bring the torque curve down just a little because the engine breathes too good especially with the Magnaflow Y-pipe and Borla exhaust on it. Would swapping in 3.2 cams make a difference and give better off the line performance?

Don't mind the swap as I'm the one who built the engine so it's really nothing to put in ATX cams if I see a better low end response.

 

[Racer X]

You could, but I would expect to see a slight drop in top end if you did.

Also, get rid of that Magnaflow Y-pipe before it clogs up and bad things happen. I'm hearing more and more about how that is becoming a regular occurrence with that pipe.

 

[SHOtime2511]

How much porting did you do?

 

[jimtash]

You could, but I would expect to see a slight drop in top end if you did.

Also, get rid of that Magnaflow Y-pipe before it clogs up and bad things happen. I'm hearing more and more about how that is becoming a regular occurrence with that pipe.

I have a PP Y-pipe sitting around but the reason I took it off is because the large tubes took away too much bottom end. Any other recommendation?

 

[jimtash]

How much porting did you do?

I bought the heads already ported and there is a good bit of difference between those and the stock heads. I also cleaned up the valves and put new seals all around.

I'm happy with the engine but it needs a little more torque on the low end and even possibly a good tune in the computer department to make it standout.

 

[SHOspazz92]

FWIW,

My wifes 3.2 MTX has the 3.2 Cams in it. I aboslutely love driving that car around town. It gets off the line with such ease and moves pretty damned well through 1st and 2nd, I'd say probably as quick as my track car. When I drove it out to California to Visit my dad, I drove his 3.2 MTX (W/3.0 Cams) and my Wifes 3.2 MTX (W/3.2 Cams) back to back. My dads car would absolutely drestroy her car up top, but would have some catching up to do if they were race from down low.

-Sam

 

[Racer X]

I have a PP Y-pipe sitting around but the reason I took it off is because the large tubes took away too much bottom end. Any other recommendation?

Slight drop in low end torque vs. catalyst substrate being ingested into the combustion chamber and ruining the piston walls and rings.

I mean, it's your call in the end, but I know which direction I would go in.

 

[zblackbeast]

Wait.. soo what's the problem with the magnaflow y-pipe beeeeecause I've got one. Lol

 

[jimtash]

Slight drop in low end torque vs. catalyst substrate being ingested into the combustion chamber and ruining the piston walls and rings.

I mean, it's your call in the end, but I know which direction I would go in.

I hear ya but this is the first time that the Magnaflow issue has come to my attention. Who's been personally affected by it?

 

[SHOtime2511]

The cats like to come apart.

 

[Racer X]

I hear ya but this is the first time that the Magnaflow issue has come to my attention. Who's been personally affected by it?

I have.

I 86'd it as soon as I realized it was coming apart. I don't drive the car much, so when I took the engine apart for the rebuild I was pleased to find that there was no damage.

That said, it's a known fact that when the cats on these cars come apart, a high RPM shift will scavenge a ton of crap back into the combustion chambers, especially on the rear bank.

 

[zak]

I have.

I 86'd it as soon as I realized it was coming apart. I don't drive the car much, so when I took the engine apart for the rebuild I was pleased to find that there was no damage.

That said, it's a known fact that when the cats on these cars come apart, a high RPM shift will scavenge a ton of crap back into the combustion chambers, especially on the rear bank.

The stock converters will come apart as well if the engine runs rich (typically from the T stat staying open). The rich mixture loads the cats up with hydrocarbons which makes them run very hot and then thermal shock breaks away peices of the catalyst - then the failure proceeds as outlined.

If my Magnaflow Y comes off for any reason (new mid pipe project planned) I will definely be checking though.

Main complaint about the pipe is they skimped on the precious metals - my NOx readings were way higher with the only change being stock vs their Y pipe.

 

[Shoaz]

Just built a 3.0 with ported heads and am losing a little low end and gaining it up top. I'd like to bring the torque curve down just a little because the engine breathes too good especially with the Magnaflow Y-pipe and Borla exhaust on it. Would swapping in 3.2 cams make a difference and give better off the line performance?

Don't mind the swap as I'm the one who built the engine so it's really nothing to put in ATX cams if I see a better low end response.

Remember that the 3.2 cams give more low end torque to an engine with about 7% more displacement. I'm not sure that will translate as well from a 3.2L to a 3.0L.

 

[hawkeye18]

What about a Walker Y-pipe? Do they have the same problems? It might kinda be important.

 

[TimboSHO]

I thought it was only a problem having the catalyst material enter the engine if you had EGR?

 

[SHOtime2511]

Aftermarket converters in general are kinda ******.
I'd guess it has something to do with skimping on the precious metals inside.

 

[jayro]

The extra torque in the atx's come from the added displacement along with the cams. Im not sure how much the 3.2 cams would help a 3.0.

Kinda curious about the ported heads....It was my understanding that they would also reduce low end for high end gains. If so, then it's almost like your mods are fighting with each other. You may have to pick a directions. If you want torque, swap in a 3.2 and stick with the non ported heads and 3.2 cams. Just my 2 cents

 

[jimtash]

The extra torque in the atx's come from the added displacement along with the cams. Im not sure how much the 3.2 cams would help a 3.0.

Kinda curious about the ported heads....It was my understanding that they would also reduce low end for high end gains. If so, then it's almost like your mods are fighting with each other. You may have to pick a directions. If you want torque, swap in a 3.2 a nd stick with the non ported heads and 3.2 cams. Just my 2 cents

What I'm thinking of doing now instead of swapping out cams is going with Shonuts adjustable cam sprockets and moving the timing instead. The motor breathes so well that advancing the valve timing shouldn't affect the top end that much yet should give me the low end punch I'm looking for.

 

[whiteguy3]

^ Not really worth it with stock cams. At that point I would invest in some tri-flow cams which help keep low end loss to a minimal and top end is increased.

 

[rubydist]

I thought it was only a problem having the catalyst material enter the engine if you had EGR?

No, the catalyst material gets sucked into the engine when the throttle gets dropped shut - the high intake vacuum allows the engine to suck some air back in from the exhaust side.


My experience with the 3.0 cams in the 3.2 is similar to what Sam said - the thing loves running over 4k rpm - the second torque peak is much stronger than the first one. And, it doesn't get as good of gas mileage.....