Reducer Pipe for an S14 with HKS Exhaust?

[Karateboy88]

Just got myself a HKS Hi-Power Exhaust with 3'' piping.

The problem is the stock 240sx piping seems to be 2'' and the flanges don't meet up.

Do you guys recommend a test pipe or a reducer pipe to make it work? Any specific companies or eBay knock-off recommendations?

[ashibah83]

it should bolt right up to your cat, if it doesnt something is wrong, maybe look for a test pipe?

[Second Shadow]

http://www.speedwaymotors.com/....html

came up with this with a quick search, prob wouldn't know about it except I had a similar problem with stock KA exhaust when I first did my swap. you'll still need to weld appropriate size flanges on the ends, and maybe shorten the exhaust before the cat(doing something like this will add a few inches). you could use this and a short section of pipe to make a reducer test pipe.

Another option is fill in the rest of the exhaust with 3" pieces, cat, manifold, downpipe. This is a tricky option though, I think to do it you'd get a 3" downpipe and cat for an SR, then a turbo KA mani and have a 3" pipe to connect them where the turbo would normally go.

an NA KA engine isn't really supposed to be run with a 3" exhaust, thats turbo size piping, so I would suggest you go KA-T or do the SR swap at some point. just my 2 cents though.

[Karateboy88]

I figured out the problem why its not fitting: cheap muffler shop cat.

Different flanges, s***ty welds, and longer cat.

I need to buy 2 new flanges and take out about 5'' of piping.

Quick question- I see an O2 sensor before the cat, does that mean we don't need it to pass emissions?

As for the comment about 3'' being to big for KA NA then I agree 100%.

I picked this HKS exhaust on the cheap because my car didn't have an exhaust.
Modified by Karateboy88 at 8:20 PM 8/20/2009

[DMan II-40]

an NA KA engine isn't really supposed to be run with a 3" exhaust, thats turbo size piping, so I would suggest you go KA-T or do the SR swap at some point. just my 2 cents though.

WHY DOES EVERYONE SAY THAT!?!?!

I have seen dyno tests, and it has been PROVEN that 3" on a NA KA gives more power than smaller diameter piping. Stop posting this garbage, it bothers me almost as much as people chewing with there mouth open.

[Second Shadow]

WHY DOES EVERYONE SAY THAT!?!?!

I have seen dyno tests, and it has been PROVEN that 3" on a NA KA gives more power than smaller diameter piping. Stop posting this garbage, it bothers me almost as much as people chewing with there mouth open.

I wouldn't doubt that when the max HP figure comes in it reads slightly higher, but I'd love to see the torque curve on this dyno. It's not just about 6k-7k RPM.

[ashibah83]

WHY DOES EVERYONE SAY THAT!?!?!

I have seen dyno tests, and it has been PROVEN that 3" on a NA KA gives more power than smaller diameter piping. Stop posting this garbage, it bothers me almost as much as people chewing with there mouth open.

thank you, 3 inch piping will give an improvement across the board, i hate it when people say that "you will lose bottom end with 3 inch piping", no you wont, the gains will be marginal, but you will not lose anything

[ZOMG.SR20]

the gains of 3inch are a cross the board not just higher rpm

[Second Shadow]

okay, as I hate being wrong about things I decided to do some more research and came across this post in a dsm forum.

http://www.dsmtuners.com/forum....html

So it would seem that a larger pipe can reduce low end torque and power, but that doesn't mean it will. As long as there is enough volume to produce the scavenging effect, power won't be compromised. Since we have the dyno results stating that 3" is a power gain across the board, apparently our engines do produce enough volume.

Now this is just my personal theory, but I think it might have something to do with our engines being somewhat on the large size for a 4 cyl. The 1.5-1.8 honda engines we see running 3" exhausts and claim loosing the low end from it might not have enough volume to sustain the effect in that size pipe, while our typically larger displacement does. Once again, this is just my after though theory.

[jessetang]

Hey, read more, and you will find out how stupid you are.

Yes, in a perfect world, engine uses smaller piping for exhaust will lose top end while gain low end, and vice-versa. However, we are talking about a KA engine here, and there are more than enough dyno graphs posted here to prove that for a KA, you will gain hp and tq, from low to high rpm with a 3" exhaust.

Stop pulling dsm stuff and later some Honda stuff to prove you are right. Go find some 240sx KA dyno graphs and you will feel stupid.

[Second Shadow]

except for the multiple "stupid" parts.....isn't that what I just said?

I guess I will clarify a little:I was wrong about the 3" exhaust, I pulled the DSM post to explain why lots of people mistakenly think that a large exhaust will hurt the low end, and why I think it's not a problem for the KA as well as higher displacement engines.

[ashibah83]

ok we have all learned (well not all of us), lets get back to the OP and hope he can reslove his situation