My 240SX sounds like a TRACTOR???

[Banzai240]

Hey Guys,

Time for me to draw from the wealth of knowledge out there...

I finally got a header for my car this season... a Hotshot that I modified extensively at the collector to clean up the merge area...

I installed it in my '97 240SX (completely ITS legal KA24DE... right down to the legal, bone stock 95-98 cams, etc...) using 2 1/4" pipe from collector to tailpipe... In the factory location, I placed a 12" Dynomax Bullet style muffler in 2 1/2".

While I definatly have some power gains and the accelleration is noticably improved, the darn thing sounds like a Massy-Fergusen Tractor!

I'm not sure if this is normal for these, as the previous Non-IT motor I had in the car had a 12:1 motor with different cams, so it had a higher pitched and more "revvy" exhaust note...

I pulled the muffler off tonight to see if that was the cause, but it just made the same crappy sound, only louder...

The engine runs well, though comments have been made that it sounds "flat" with this exhaust... The motor has about 9-hours of race-weekend driving on it, so it's just getting broken in... Compression works out to about 200psi on a compression check across all cylinders (stock bore, lightly cleaned-up head, etc...)

Is the pipe too small? Is this the way these things sound?? I was kind of hoping for more of a "tuner" 4-cylinder revving to 7000 grand sound...

Any thoughts?

I'll post some links to some movie files shortly where you can hear for yourself...




------------------
Darin E. Jordan
SCCA #273080, OR/NW Regions
Renton, WA
ITS '97 240SX

[x-ring]

Well, I really know zip about the KA series, ad this may sound obvious, but did you do a baseline dyno before you modified the header or with the stock exhaust?

My feelings on sound are, if it makes it past sound control, and it's working well, who cares what it sounds like. No one will comment that your car doesn't sound good if you beat them



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Ty Till
#16 ITS
Rocky Mountain Division

[Banzai240]

Originally posted by x-ring:
Well, I really know zip about the KA series, ad this may sound obvious, but did you do a baseline dyno before you modified the header or with the stock exhaust?

Previously, the car didn't have a header, just a cast-iron manifold... Definite gains, and better revs up top...

As for the not worrying about what it sounds like... Apparently, you don't have the racing buddies I do! They don't pass up one opportunity to RAZZ me!

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Darin E. Jordan
SCCA #273080, OR/NW Regions
Renton, WA
ITS '97 240SX


[This message has been edited by Banzai240 (edited October 22, 2004).]

[Geo]

Must be the truck engine.

Actually, are you certain there are NO exhaust leaks? Perhaps a crack induced somewhere in the merge collector?


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George Roffe
Houston, TX
84 944 ITS car under construction
92 ITS Sentra SE-R occasionally borrowed
http://www.nissport.com

[erlrich]

Darin - FWIW, all of the ITA 240s I've heard (while flagging) have had that 'distinct' sound. Never really occurred to me, but I guess you could compare it to your basic John Deer.

------------------
Earl R
Aspiring 240SX pilot

[Tristan Smith]

Darin, I have had extensive sound level issues, so I now run a 2 chamber flowmaster muffler. It definetley quieted it down, but my car has never sounded flat like that. I watched a video tape this year that has me driving by at full accereration. I was amazed that the car sounded so "snarly" and "raspy". My advice, if it works, and you pass sound, just drive it.

------------------
Tristan Smith
Buffalo's Southwest Cafe
ITA Nissan 240sx #56

[MMiskoe]

Well, its a four cylinder...

Seriously though, I have heard a lot of 4 cyl cars that go like stink but sound like crap, especially at low RPM. Friend's 240sx tends to sound rough at low speed.

Listen to an older flat 6 porsche - sounds like a bucket of rusty bolts at idle, but better than any other race motor at full song.

If it pulls well, just put in ear plugs, your pals will stop ragging you when you pass them!

[Greg Gauper]

FWIW - Think about it....SRF's have a crappy exhaust note too.

Volvo's aren't much better.....

[its66]

Darin,
I don't have any experience with the 16 valve engines, only the 12's. I would think that you might benefit even more from a slightly larger exhaust (2 1/2 for sure, and maybe even 3 inch) I don't think that is the source of your tractor noise though.
If you cut the collector off and welded/slid on a merge collector, check inside the merge, between the four pipes on the inlet side, for leaks. I have had them split there. Just a possiblity.
How much vacuum does it pull at idle?

Jim Cohen

[Banzai240]

Originally posted by its66:
I would think that you might benefit even more from a slightly larger exhaust (2 1/2 for sure, and maybe even 3 inch)


... How much vacuum does it pull at idle?

I'm building a second system this winter of 2 1/2" pipe to test, but we feel that the 2 1/4" keeps exhaust velocities up to a reasonable level and helps enhance the "truck-like" features of the 4-valve motor...

I'll have to do a vaccuum test too... don't have an in-car vaccuum guage, so I'm really not sure how much it pulls... Good Question I guess!

------------------
Darin E. Jordan
SCCA #273080, OR/NW Regions
Renton, WA
ITS '97 240SX


[This message has been edited by Banzai240 (edited October 25, 2004).]

[lateapex911]

Lets talk headers. Darin, yours is a 4 into 1, right? What is the theory behind differing lengths and differing collector arrangements?

Bikes (some) run 4 -> 2 -> 1 -> 2, and I have to tell you my Ninja with the Yoshimira pipe sounds so sweet...and LOUD, but sweet that I have so far held off onmy "Ducati dream"....

You might look into the benefits of tuned lengths and different collector strategies.

Also, perhaps there is something to be gained in expanding the pipe as you continue further back.

PS>>>glad to see you working on your car, not just ITAC stuff. (I do appreciate the effort and time you put into the position, though. Thanks)

------------------
Jake Gulick
CarriageHouse Motorsports
ITA 57 RX-7
New England Region
[email protected]

[Banzai240]

Originally posted by lateapex911:
Lets talk headers. Darin, yours is a 4 into 1, right?

Actually, mine is a "tri-y"... 4 -> 2 -> 1 with 1&4, 2&3 y'd together...

Has to do with evenly balancing the pulses at 180 degree intervals or something like that...


------------------
Darin E. Jordan
SCCA #273080, OR/NW Regions
Renton, WA
ITS '97 240SX


[This message has been edited by Banzai240 (edited October 26, 2004).]

[Ron Earp]

Darin,

try another muffler. It is a four cylinder and can be made to sound like any other four cylinder of similar displacement.

I have this muffler on my 2.2L turbo Esprit, and it sounds quite nice. Used it on other naturally aspirated fours before and I think it is a fantastic muffler for the price and doesn't rob power.

http://www.jegs.com/cgi-bin/ncommerce3/Pro...338&prmenbr=361

Or look for Moroso Spiral Flow mufflers if the link doesn't work. I use a 3" on the turbo Esprit and will probably use a 2.5" on the JH.

Ron

------------------
Ron
http://www.gt40s.com
Lotus Turbo Esprit
Ford Lightning
RF GT40 Replica
Jensen-Healey: IT prep progressing!

[This message has been edited by rlearp (edited October 29, 2004).]

[Banzai240]

Originally posted by rlearp:
Or look for Moroso Spiral Flow mufflers if the link doesn't work. I use a 3" on the turbo Esprit and will probably use a 2.5" on the JH.

Ron

Interestingly enough, this was my next move... You can also find these called "Auger" mufflers. You can buy the spiral part seperately to fit inside a 3" or ??? exhaust tubing so you can make your own... Cheap to do, as the center section was only about $15.00 last time I checked...

I'll let you know how it turns out...



------------------
Darin E. Jordan
SCCA #273080, OR/NW Regions
Renton, WA
ITS '97 240SX

[Ron Earp]

------------------
Ron
http://www.gt40s.com
Lotus Turbo Esprit
Ford Lightning
RF GT40 Replica
Jensen-Healey: IT prep progressing!

[This message has been edited by rlearp (edited October 30, 2004).]

[bill f]

Darin,

Not the same motor, but the displacements are similar...

On the 2.3 Liter Ford we were using a three inch exhaust at the recomendation of the header merchant. It went to the rear axle, with a "down turn", and no muffler.

Wasn't "flat" sounding.

Still interested in "Ford" talk?

Write me.

Bill

[Ron Earp]

Darin,

The inlet and outlet of these things might be 2.5" or 3", but, the center section is more than 4.5" in diamter. So, I don't think you'd get the same flow by putting the sprial baffle into a 3" pipe. It's only $45 complete, bite the bullet and buy one! ;-)

Ron

[Joe Harlan]

The problem may be your engine builder has installed aftermarket muffler bearings in the thing....

Oh and if you are gonna pit with me from now on you need to be wearing a straw hat for driving that tractor around.

[ITA240]

Joe,
I've never had any problems using aftermarket muffler bearings, as long as they were the proper undersize, and have the extra oiling groove. Perhaps they were not broke in properly??
All this tractor talk makes me think maybe Darin is planning a few "agricultural excursions".

Jim

[erlrich]

Originally posted by ITA240:
Joe,
I've never had any problems using aftermarket muffler bearings

Hey - are those IT legal? I might have to try them!

Earl