Questions about FI bolt-ons

forza370z · 08-02-2012, 08:30 PM

Quote:

Originally Posted by KingJoseph

(1) Does the Nismo have the same cats as the base 370Z (i.e. can I expect the same gains that FI quotes on their website for HFCs or test pipes)?

(2) FI offers 300 cell and 100 cell HFCs for the 370Z. Is there any disadvantage to using the 100 cell cats on a naturally aspirated Nismo? It specifies that they were designed for turbo/supercharged vehicles, but they are lighter and (presumably) less restrictive.

(3) The test pipes appear to be heavier than the HFCs. Is this right? The test pipes are the pipes minus the extra hardware as I understand it.

(4) Can anybody comment on the FI exhaust volume without resonators vs 12" vs 18" vs stock Nismo? Any of the above would be much appreciated.

Thanks in advance... decisions, decisions!

(1) Yes. They all have the same cats.

(2) Not too sure on this one, but I remember Tony told me it's for tuning. More cells gives you extra band.

(3) Test pipes shouldn't be heavier than HFCs coz they are just straght pipes.

(4) If 10 being the loudest and 0 being no volume at all: FI CBE = 9, stock Nismo = 0. Naw... just kidding. Stock Nismo = 5. Resonateors and non-resonateors are no big deals IMO. It's just used to cancel out the in cabin drone.

KingJoseph · 08-02-2012, 11:17 PM

Quote:

Originally Posted by forza370z

(1) Yes. They all have the same cats.

(2) Not too sure on this one, but I remember Tony told me it's for tuning. More cells gives you extra band.

(3) Test pipes shouldn't be heavier than HFCs coz they are just straght pipes.

(4) If 10 being the loudest and 0 being no volume at all: FI CBE = 9, stock Nismo = 0. Naw... just kidding. Stock Nismo = 5. Resonateors and non-resonateors are no big deals IMO. It's just used to cancel out the in cabin drone.

Thanks for your well spoken response. I've got a call in to Tony, but I think they're in the midst of a move because they haven't answered my email and I got an auto-response saying something to that effect.

So, it sounds like with less cells on an NA engine, I'd be sacrificing some of the powerband for a minimal HP gain. Am I understanding that correctly?

wstar · 08-03-2012, 09:16 AM

Quote:

Originally Posted by KingJoseph

So, it sounds like with less cells on an NA engine, I'd be sacrificing some of the powerband for a minimal HP gain. Am I understanding that correctly?

More or less this is a correct approximation of the situation. Within reasonable design limits, if you remove some restriction from the exhaust the torque peak moves upwards in revs. Since HP = Torque*RPM, this increases "Peak HP", but that peak will come at a higher rev than before. That doesn't necessarily mean you improved the total area under the curve on the torque graph, depends on a lot of variables whether a given exhaust change does that for the rev range you care about.

Most people driving on the street will dislike a change that pushes the HP Peak up the graph, because they spend most of their time in the lower rev range and it'll feel like a loss. On the other hand at the track I spend most of my important engine time in the 4K -> 7.5K range, and below say about 3K RPM I just really don't care if my torque drops off sharply, as long as I get solid gains in the range that matters to me.

tjlazer · 08-04-2012, 11:05 PM

Quote:

Originally Posted by forza370z

(4) If 10 being the loudest and 0 being no volume at all: FI CBE = 9, stock Nismo = 0. Naw... just kidding. Stock Nismo = 5. Resonateors and non-resonateors are no big deals IMO. It's just used to cancel out the in cabin drone.

I do not agree. 10 = Meistershaft GTS CBE! FI CBE = 8.

I had both so I know. :P

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