I have a 98 s14a. Aem intake, ApexiN1 catback (75-85mm). I have a hotshot header in transit to me right now. When i install the header, it will replace the primary catalytic in the downpipe, leaving me with the dummy cat under the drivers seat.
I also have a chance to purchase one of the Heavy Throttle pre-welded Catco 3" high flow catalytic converters for 100 bucks shipped.
Here is my question:
Knowing that the exhasut is a little bit too big for the car now (even though it runs great with this catback on it, very little low end loss), should i go ahead and get the 3" catalytic to replace the dummy cat?
With the header/HT cat/N1, will i have any real performance problems? Should I just get a 2.25" Catco, have it welded and call it a day?
The only reason i am considering this is that the cat is cheap for me to purchase.
I have no plans to turbo within the next three or four years, so I am getting a header instead.
What are your recommendations?
Exhaust Question
I may be wrong, but i think the cat that is attached to the header is the resonater adn the one below the seat is the actual cat. So then you should be ok. I have a catco from heavy throttle with my sr swap, and i have no problems with it...but if you measure it, i think you can get a universal app. from summit for way cheaper.
this is pretty ambiguous because i have heard multiple stories on the fake cat / downpipe cat thing, but personally, my cat is in the DP and the one that looks like a cat is just fake.
camel - why bother spending 100$ on a cat? do you have emissions testing? if not i say screw it and run the open cat. hell even if you did have emissions testing i would swap back the stock exhaust system before i spend a hundred bucks.
camel - why bother spending 100$ on a cat? do you have emissions testing? if not i say screw it and run the open cat. hell even if you did have emissions testing i would swap back the stock exhaust system before i spend a hundred bucks.
Well aside from the obvious environmental effects of not running a cat (which will eventually catch up to you via stricter emissions laws when the smog levels in your area do reach that point) it's also there to add a bit of torque at the low end. My neighbor who's got a 97 s14 turbo gutted his cat before. Lost a great deal of low end and said it felt like crap. He then went with a 3" magnaflow and was very pleased.
If you're not going turbo, give the 2.25" or 2.5" catco's a try. I actually got my 3" catco from ebay new which should come in tomorrow and although needs flanges welded on, got it for 50 shipped. Might want to give that a shot. But for NA applications and even if you do decide to go turbo sooner than you thought, the 2.5 should be sufficient to serve you well.
If you're not going turbo, give the 2.25" or 2.5" catco's a try. I actually got my 3" catco from ebay new which should come in tomorrow and although needs flanges welded on, got it for 50 shipped. Might want to give that a shot. But for NA applications and even if you do decide to go turbo sooner than you thought, the 2.5 should be sufficient to serve you well.
the thing with all this exahust work is your egr will be greatly effected since there will be no back pressure. On accel the ECM figures in egr operation and adjusts mixture ratio accordingly. If you go with a larger exhaust your back pressure in the system will drop therefore not allowing your EGR to open. The computer still compensates for when it expects it to open so you may feel a bit of power loss on accel lower end. If you are all balls about doing this I would recommend getting a chip for the ECM that factors out EGR operation. If you do that screw the cat just replace the smaller fake cat with a fabricated straight pipe from the header to the catback pipe.
Here's the deal tho, I already have the catback on the car with no i'll result. The header is going to have a place for the egr tube and it should work correctly. I have a small amount of low end loss on accel that is negligable. I attributed this to the larger pipe diameter considering that i had gains in the mid to high rpm ranges.
What i am wondering is if using a factory sized cat to replace the dummy cat after the headers go on would maintain the backpressure that i currently have. As well as fabricating this "velocity extension" that goes back into the catback that is already on the car to increase the backpressure a small amount back toward the stock amount in order to regain some of the tq that was lost.
I do need to have a cat, i do care about the environment and cel's. So I may try this plan to see how it works out. The fab work is free for me so no harm no foul.
Does anyone know the diameter of the inlet on the stock cat?
What i am wondering is if using a factory sized cat to replace the dummy cat after the headers go on would maintain the backpressure that i currently have. As well as fabricating this "velocity extension" that goes back into the catback that is already on the car to increase the backpressure a small amount back toward the stock amount in order to regain some of the tq that was lost.
I do need to have a cat, i do care about the environment and cel's. So I may try this plan to see how it works out. The fab work is free for me so no harm no foul.
Does anyone know the diameter of the inlet on the stock cat?
well heres my "theory" on these "2 . whatever or 3 inch" exhaust systems. if you go from a whatever inch header into a smaller pipe[the fake cat] what the hell is the point. your going from a large pipe into a smaller one. it seems to me you would be defeating the purpose of the larger pipe. If your gonna go large exhaust do it all the way back or its not doing anything. But on the other hand it looks real good. like I said I am not up on all this performance stuff I fix them as they were manufactured.
That is my opinion. so dont take it as a personal insult or notin.
That is my opinion. so dont take it as a personal insult or notin.
