Looking for a 4" catback (Apex'i?)

[!^3]

I have heard rumors that Apex'i makes a 4" catback for the 1g AWD DSM. Is this true? I can't speak Japanese so their www.apexi.co.jp site doesn't really work for me, . I can't find this exhaust with any of the typical vendors either...just Buscher with their 3.5" (another exhaust that I am considering). If anyone has any info or a link, I would greatly appreciate it!

 

[boostedinaz]

why do you want an 800+ hp eclipse .... well all im gonna say is good luck... BTW: not insulting I just wanted to know... Cuz I don't think Shep's car is over 800 hp...

To trap the speed that he does he needs to make about 1000 to 1200 hp at the flywheel unless he car is super light. Super light would be less than 2500 lbs.

Michael

 

[!^3]

To trap the speed that he does he needs to make about 1000 to 1200 hp at the flywheel unless he car is super light. Super light would be less than 2500 lbs.

Michael

Yep...he was at 750whp when he was running 10's. Now he is running 8's. That is more than 50 extra hp BTW, his vehicle weight with driver is 2650.

Why do I want it? Because I am a crazy mofo

 

[Twizzle]

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im sorry, it was just the right place at the right time...i had to post it even if it is an old pic.
oh and with all that power you plan to have....i'd ditch the 19's wrapped in electric tape

 

[kpt4321]

Low range hp may be affected due to the turbo having not spooled yet and the vehicle is working as an N/A car, and thus benefitting from the added back pressure.

Be careful when you make claims about your physics knowledge, and then say that backpressure is helpful.

Backpressure is never ever good.

 

[Twizzle]

the wiseman has spoken!

 

[boostedinaz]

Backpressure is never ever good.

Are we talking about turbo cars or just in general. N/A motors can get some use out of some backpressure. This is in a full race environment but it does help to have the exhaust tuned for the vehicle and powerband of the motor.

Michael

 

[LandoAWD]

Are we talking about turbo cars or just in general. N/A motors can get some use out of some backpressure. This is in a full race environment but it does help to have the exhaust tuned for the vehicle and powerband of the motor.

Michael

I was called out on this terminology not too long ago myself.

From Kevin Jewer (95 GSXracer):
False. Backpressure is never good. You want velocity, to exploit the scavenging effect and pull more aif/fuel in during valve overlap. Smaller pipes increase velocity, thats physics. Increased backpressure is a sideeffect of smaller pipes. So unfortunately poeple confuse the two. Its also possible to increase velocity efficiently, meaning less increase in backpressure pre increase in velocity. Thats the whole trick... Ehxuast backpressure has no effect on comrpession ratio.

__________________

 

[boostedinaz]

I guess I shoudl have just said that a well tuned exhaust sytem will help power. On a ProStock car at the end of the collector it necks down from about 3 inches to about 2.5. This is to help with scavenging using the venutri effect, basically the exhaust acts like a carb. They could just run open headers but then they will lose power do to the loss of the venturi effect. I would imagine that this causes some back pressure, perhaps not much at all, but some.

Michael

 

[!^3]

These 19's will own all you haters! j/k

I "wear" the TSW Sting 19's around town because I don't want my car to look like crap, hehehehehe. These cars have the hardest wheel gap to fit of just about any car I have ever dealt with, but my 19's/Nitto rubber bands fit the bill well. It would be funny to have the fastest DSM on 19's, but the car will receive some type of drag friendly 16" wheel/tire setup.

Thank you for correcting me, increased velocity is the true benefit of smaller pipes, not backpressure. Backpressure is just more easily conceptualized than velocity and perhaps why it is falsely believed to be more accurate.

The decrease in velocity when stepping to a larger exhaust, all things held constant, is the major reason why people get a deeper exhaust note than with the smaller exhaust (otherwise measured as the "Mach" velocity). Kind of like the doppler effect...fast moving things have a higher pitch than slower moving things.

What is interesting is when we try to tune and mod our cars, there are two basic things we are trying to increase; fuel flow and air flow. It is amazing how simple an idea like this becomes so difficult in the real world.

BTW crankbender, I have considered going with a methanol setup. However, I would like to keep this car as daily-drivable as possible without having to change out a lot of stuff that would bar me from being able to safely run pump gas. However, it is still looming in my mind how much power could be created with 40psi/9+ compression We'll have to see

 

[Quasimondo]

You sure you're not building up a 4G63TD (turbodiesel?) That's a mighty large pipe you're fabricating. :laugh:

 

[stuffy1256]

stupid question but.... why not just get a big cut out? get the 3" Dp and like a 3/3.5" cut out or even better have the cit out right out of the 02 housing, ive seen it done before. With what you are saying, no exhaust it good exhaust. Yeah it wouldnt be legal, but what I gather from your posts, its just going to be a fun car and not be in competitions so you dont have to worry about being legal. IMO that would be your best exhaust.

 

[EvolvingGST]

Yep...he was at 750whp when he was running 10's. Now he is running 8's. That is more than 50 extra hp BTW, his vehicle weight with driver is 2650.

Why do I want it? Because I am a crazy mofo

hahaha i read somewhere about the 750 whp.. thanx for clarifying

 

[revision27]

Sweet, thank you! Doesn't look like the GT Spec has been released for the DSM yet, but should be soon I hope. Maybe that's why no one uses it yet

It seems that most of the feelings toward 4" exhaust are merely "I don't need it, why would you?" or "Shep doesn't need it, why would I?" No one has actually taken two cars and performed actual dyno tests between 3", 3.5", and 4", so I will trust physics before I trust anything else. IMO, everyone needs 4", so why not? Even Shep would benefit from it. That and I will need to go with something larger than 3" for the power I intend to make by next summer and the Apex'i seems to be priced cheaper than the Buscher...and it bolts right up to the 3" N1 downpipe.

Also, Apex'i is supposedly the only company in the world with a 4" mandrel bender (actually 3.8").

Thanks for the link to that thread, but I found it rather useless...more like a bunch of people not knowing what they were talking about. Are they saying there is a magical formula for exhaust sizing? And it changes 2-3 times throughout the thread! Are we supposed to take an average of what people think, or go by hard numbers? Forums are great, but that is an example of why forums are not. Just a lot of people who mean well, but overall, they are only providing their own personal speculation. Which I wholly respect, but the base of most of these speculations is ungrounded.

Just because we haven't seen an exhaust this large until now does not mean anything...not so many people have been putting out 700+ until recently with DSM's! Turbo engineering/design has come a long way in the past five years, both in efficiency and economics, and the sport compact scene is now benefitting from it, allowing us to get mad power out of smaller engines. They've been getting 1000+hp out of 2 liters for years (i.e. Pikes Peak Tacomas in short distance hill climb form were putting out 1400hp with a 2.1 liter). Most of these vehicles use short side exhausts or very large diameter exhausts. Exhaust size does not change for DSM's...instead, flow and the basis of the aspiration of a 2 liter govern exhaust sizes. I am sure years from now people will think 4" is more accepted as people continue to raise the bar of output as engineering brings down the pricing of large-power modifications. But we shall all see

i might be wrong but wouldn't bolting a 4" catback to a 3" downpipe defeat the purpose of having a 4" cat-back?

 

[!^3]

i might be wrong but wouldn't bolting a 4" catback to a 3" downpipe defeat the purpose of having a 4" cat-back?

Not at all. Expansion of the exhaust, as long as the maximum increase is no greater than 8 degrees, will improve flow. Of course, a straight-through 4" would be great too, but it would be near impossible to get 4" of pipe to fit in there.

So many jokes about not needing this power, ...so many people will never need this power

 

[Eagle 5]

Physics said that it is immposible to get a vehicle to go over 300 MPH in a quatermile distance from a stand-still, so it can be wrong.

Physics is not wrong in this sense. The fastest you can accelerate is whatever the speed of gravity is as the fricitonal force is equal to F=(mu)N where mu is the coefficient of Static friction. When this was being figured out etc, they thought it would be impossible for there to be a mu > 1. rubber on concrete is as close to one as you can really get.

HOWEVER, they did not knwo that there would be substances such as the rubber on slicks that when they get hot they get very, very sticky. This makes them almost like glue sort of and allos for a much greater mu, to the potin of mu> 3 or even 4. Physics was not wrong, in nature by itself, mu = 1 is the greatest, but we can make compounds greater than that. Anyway, I think you get the idea here Physics was not wrong at the time, thigns change and people foudn a way.

Another example. Everyone knows diamond is the strongest material on earth..... wrong, carbon nanotubes are stronger than diamond. They are made of the same basic componet... carbon, but these nanotubes are much much stronger than diamond is. Do a search on it, pretty cool stuff.

 

[DSMkid311]

at what point does the weight of the exhaust pipe out weigh the flow of that same pipe?

a dyno is going to give you your wheel horse power, but it doesnt factor in the weight of your car. my point is, so what if a 4" exhaust adds lets say 10 hp over a 3.5". you have to lug all that extra weight which is going to lower your ET.

just my .02

 

[!^3]

at what point does the weight of the exhaust pipe out weigh the flow of that same pipe?

a dyno is going to give you your wheel horse power, but it doesnt factor in the weight of your car. my point is, so what if a 4" exhaust adds lets say 10 hp over a 3.5". you have to lug all that extra weight which is going to lower your ET.

just my .02

This is when you look at your hp/weight ratio. Say it is 400hp/3000lbs (.13333). With the 4", it becomes 410hp/3020lbs (.13576). The added weight is not necessary in this scenario. However, this is why we have titanium exhausts. I am also willing ot bet that on a high-strung out car, the gains of a full inch in diameter would be much larger, e.g. 30-50hp in the top-end.

And just to let everyone know, the GT Apex'i exhaust is no larger than 3" for the DSM. It is 3.75" for the 240SX and the RX7 (FD3S).

 

[n3gativerr0r]

Just get a full 3 inch system and a QTEC cutout or better yet TAKE THE EXHAUST OFF when you go to the track and run open DP. Dropping what like 1000 dollars on a 3inch neck up to 4inch system from Apexi is just ####ing stupid.

 

[!^3]

Just get a full 3 inch system and a QTEC cutout or better yet TAKE THE EXHAUST OFF when you go to the track and run open DP. Dropping what like 1000 dollars on a 3inch neck up to 4inch system from Apexi is just ####ing stupid.

Hmmm...okay, right. Considering a full 3" will be close to $1000. Is 3" for $1k worse than 4" for $1k?

 

[n3gativerr0r]

Your looking in the wrong places.. and if I were you and was looking for a 4" I definately wouldnt be looking online. Go to a local shop and get it fabbed up. Really though run open DP they dont make 4" systems for a reason.

 

[!^3]

Your looking in the wrong places.. and if I were you and was looking for a 4" I definately wouldnt be looking online. Go to a local shop and get it fabbed up. Really though run open DP they dont make 4" systems for a reason.

I figured if there was a prefab 4" I'd go with that, but it appears there is not. Thanks for the advice.