The great HFC question for newbies
 

Ok, I'm sure this has been spoken of before. However I'm unable to find it.

Whats up with all the different HP numbers with HFC's?

The berk cats show some crazy gains of like 15hp by themselves.

However the F.I cats only had a gain of 4 or 5 hp when dynoed with the FI cat back system.

I know the F.I cell count is higher. However would that matter?

So is it a simple case of HFC (15hp)+ Exhaust (18hp) = 33hp gain?

How do the numbers work when pairing HFC's with a cat back exhaust?

The 3.7 engine is weird like that. The very first intake/exhaust mod you do... intakes/HFC/TP/CBE etc, will always net you the most HP... roughly 15hp... and any of those mods after that, will give you single digit gains.

From what I understand, it doesn't matter what order you install things either.

So if you install a CBE first, you get the most gains... if you install HFC first, you get the most gains... if you install intakes first, those give you the most gains, etc. etc. etc.

Hfc's will give 15hp if its the first exhaust mod but if done after cbe , it'll only give 3-5hp more...all hfc's should yield similar results

hmmm its weird, I mean based of the numbers. Berk HFC's and FI cat back would be the dream team combo for max gains.

Has anybody done a dyno comparo between Berk HFC's vs. F.I. HFC's, like directly with an aftermarket exhaust? Some members have shown gains as much as 36whp using a Stillen exhaust + Berk HFC's.

I assume the F.I. HFC's didn't gain much because it uses a 300 cell metal substrate cat. Which isn't that much better than stock. Tony from F.I. claimed that HFC's don't make that much of a difference because once he put his high flow cats on after his exhaust, it only gained maybe 5whp. That's probably because his HFC's are a lot more restrictive than Stillen and Berk's. Member's here on the370z have been spreading this misinformation on since then.

The Stillen and Berk HFC's uses 200 cell metal substrate cats, which is MUCH higher flowing. When I switched out my 300 cell high flow cat on my STi to a Magnaflow 200 cell unit(which is a similar one that Berk uses), it gained 14whp after a little tuning to comphensate for the extra flow. That extra 100 cell difference actually restricts the exhaust more than you guys think.

The reason why I think F.I. chose a more restrictive 300 cell design is probably less chance of triggering the check engine light. Think about it guys, when I had a 300 cell high flow cat on my STi I didn't even need a 02 sensor fix.. Once I put on a 200 cell unit, I had to rig up a non-fouler 02 sensor fix.... Just shows how much more a 200 cell unit will flow.

In a seperate forum, the Berk's HFC's showed an increase of 24WHP/23TQ....The average seems to be 15HP gains...

In regards to your question whether HFC(15HP) + Exhaust (18hp)=33Hp gain..the answer to that is NO...A Cat Back Exhuast will add an additional 10-15 HP...

The Berk HFC/Cat Back Exhaust Combo has gone to show a 36WHP gain...As stated by Dan37TZ...It all depends..If you want the highest HP gains, I say go with the HFC/CBE combo...This combo has shown to give the most WHP/TQ gains...Now once you buy a Stille CAI...don't expect to get an additional 18HP as advertised...You will receive less HP gains since you now have a HFC/CBE combo...Now if you had a stock Z and slapped in the Stillen CAI..you may see a 18HP gain by this mod alone...Some reviews here have shown that a CAI set up will only show you gains at 7K rpm and above...This has made others come to the conclusion that the stock intakes are suffice

Interesting thread.

I've got my CBE done and have dropped in some K&N panel filters (have not done a dyno run yet, so I have no idea about the power gains - it just feels a bit more responsive and, interestingly enough, more powerful around the 2.5-4k rpm band). I was considering the Gen3 intake as a next step, but now I am thinking I should really fit the Stillen or Berk HFC's first and see whether I want to do the intake after that. THe exhaust is actually not very loud and I like it that way. Am a bit worried the HFC's will add a lot of noise.

Edit: Just noticed the age of the thread --- whoops :-)

:icon18: me too!!

Nice thread actually I have been wondering the same questions listed and I like the replies. I just installed my first mod, a FI CBE and I feel a difference in performance but now I ordered my k&n drop ins and the HPS tubes and soon the Berk HFC, unless I hear other cats are better

Test pipes FTW! :D

You get diminishing returns because the engine only needs so much breather mods for maximum gains. Keep in mind for those getting full bolt-ons, you need to get a tune to even out the a/f ratio and also add a little more power. Not to mention it will give you a better throttle response.

Question from the dead...but I'm VERY curious where alllllll of this information came from^^^^ I literally laughed twice as its mentioned, "Member's here on the370z have been spreading this misinformation on since then." Sorry Dan37TZ, but this entire paragraph of information is 100% incorrect.

BERK uses the cat core #59956, which is a 300 cell magnaflow cat. Unless someone can correct me on this that they've changed what core they use? I know everyone claims they use a 200 cell cat, but that's not correct.

The "assumption" that FI didn't gain "15 horsepower" just off the cats vs 5hp, is because when pairing breather mods, your percentage of gain will drastically decrease.

Example - If you add JUST HFCS (no aftermarket exhaust), the potential for percentage of increase (10-15hp) is MUCH HIGHER then if you already have a catback, which you've already opened up the backpressure some and gained probably 15-20hp....adding HFCs to the already installed catback will not gain you ANOTHER 10-15 hp on top of the already installed catback increase.