exhaust improvement on q

[sijoko]

The factory setup on the Q is pretty good.

The only part that I would tell you to change is the rear resonator. Replace it with a straight through muffler such as a Magnaflow or an Ultra-Flow.

The exhaust on the Q is a little over 2 inches in diameter.

According to an automotive performance book that I have, dual 2 inch pipes are good for over 600 bhp.

There really isn't that much power to be gained on the exhaust side, except with custom, properly-designed headers.

I have messed around with different exhaust mods for my 94 Q. Right now, I have a system that I welded up myself.

I have 2.5" diameter tubing with an X-pipe and Spintech mufflers and some straight through mufflers at the rear. I used mandrel-bent tubing so that there are no reductions in pipe diameter.

Did my little do-it-yourself exhaust make gobs of power? Probably not, but it sure does sound nice.

In the end, the sound is probably what you will notice more than performance.

As far as using the flex piping, it will create turbulence in the exhaust flow. A small section of flex pipe won't be a problem, but a longer section might end up creating more resistance than the stock setup.

-sijoko

[elwesso]

PMQ, you really need to read the previous posts before you start posting threads on here....

Maybe we could prevent him from posting for one day so that he is FORCED only to read

[pito11213]

Why would we do that Wes. He has stated that he read the previous threads, but did any one discuss a cut off valve before? He is just putting ideas out there and whether or not they have been discussed before or not is irrelevant. That is like saying to someone who asks "should I use mobil1 or castrol oil." Sure they will read the posts but may have different suggestions or ideas. We must get out of the habit of there being only one answer and one solution.

[HeavyDuty]

I believe there are a couple of cars that use a electric operated bypass baffle in the mufflers that are actuated by throttle position & rpm.

"Dumps" are a good name for them, they sound like a "Dump" truck.

There are aftermarket electric dumps available.

Quick question, Tech, if you don't mind.....If one were to remove the inboard mufflers & replace them with straight through high quality stainless resonators, would a slight increase in volume & a slight decrease (lower) tone be achieved?

I know you've mentioned they are a straight through design, have you cut them apart before? Sometimes an offset or even a straight through design has dead end chambers that force the gases through sound deadening material & baffles, etc. Just curious if they do flow straight through?

Also, Sijko, I put a caliper on my 91 stock system & there are quite a few areas where the OD was less than 2". I want to say it was more like 1.75" on the H pipe crossover. An ideal system to me would be 2" mandrel bent with an X pipe like the BRM, and BRM all the way back. (Dual mufflers inboard with an additional rear muffler.

[PoorManQ45]

What sort of "electronic bypass valve" will withstand the exhaust gas temps? Electronics usually require insulators of some sort. And you will put one on each pipe from the head, or lower down? Not much room anywhere, is there?

It's a valve that is opened and closed by a solenoid. There are companies that make them already. But, I'm good with electronics and plumbing, so, I would/could probably make it myself.

These bypass vavles are labeled for Off-Road use only, IIRC. Besides the legality of the system, are there any other problems that I might run into?

Lastly, you expect this valve to reduce restrictions, or is it just to make things louder?

I would think that cutting off the entire exhaust would reduce restriction. At what RPM range is the stock exhaust most restrictive. I could go high tech with this job. I could make an electronic switch that is controlled by the/a tachometer. Opening the valve when the stock exhaust becomes restrictive, closing it when it's not restrictive. This would make it so the restriction was/is immediately eliminated right before it begins. Is that close to right?

About noise. As long as it doesn't sound like a honda with a coffee can muffler, it would be ok with me.

BTW, I thought the long-held most *cost effective* ($/hp) mod you can do is the JWT ECU.

JWT ECU is the most cost effective, if you buy stuff off the shelf. If I can make a new exhaust or install bypass valves in the exhaust for less than $50, it would only have to make ~3~5hp to make it more cost effective. I think I got that right.

Can anybody give me an estimate of how much HP I would make. Relative to the most restrictive RPM range of the stock exhaust.
Modified by PoorManQ45 at 10:48 AM 9/17/2004

[maxnix]

PMQ, you really need to read the previous posts before you start posting threads on here....

Amen, Rev. Wes! Praise the facts! Cast out idle speculation and gross imponderables!

The F50 does have a variable muffler like the 3rd or 4th Generation Maxima. I think it is controlled by the OBD II system relative to engine rpm.

Bottom line, with enough money, one can drop a Ferrari V12 in there. What's the point of all this "what-if" speculation? It is more valuable to report on on real world trial and error facts like Q45tech, but much more difficult to achieve than armchair speculation or bench racing.

In PMQ45 terms, like the difference between -ahem- "reading" Hustler or really "dating" a super model. Idle fantasy is no substitute for the real thing.

[rsiwicki]

"Has anybody here replaced the entire exhaust, except for the headers? Has anybody ran straight pipes?"

Me!!!!! I think that I might have lost a little bottom (low-end) torque...but the trade off is nice as I don't get the drop off either after 5,000rpms like I use to and so the freeway cruiser is a real monster now....

[PoorManQ45]

Me!!!!! I think that I might have lost a little bottom (low-end) torque...but the trade off is nice as I don't get the drop off either after 5,000rpms like I use to and so the freeway cruiser is a real monster now....

That's why I suggested using a valve to change the flow of the exhaust. I would get the low-end of the stock exhaust, and better high-end with the modified flow.

Would this modification be worthwhile? I would like to keep the stock sound exhaust, most of the time. I would only be dumping the exhaust in a few situations. One would be that there is an annoying 4-banger next to me with a "loud" exhaust revving his engine. I'd dump the exhaust and then rev the engine. If he still wanted to go. I'd close the valve(stock exhaust) to begin with(don't want to lose low-end torque:( ), then I would dump the exhaust as the RPMs rise above ~4k~5k. Would this give me a little more high-end HP/torque?

Modified by PoorManQ45 at 3:20 PM 9/17/2004
Modified by PoorManQ45 at 3:21 PM 9/17/2004

[AZhitman]

Please don't street race anyone.

This scenario is almost as absurd as it gets. Let's get your Q back to "as-new" condition, and you won't have to worry about "revving" on people at stoplights (which is incredibly juvenile, especially in a Q45).

[elwesso]

Please don't street race anyone.

This scenario is almost as absurd as it gets. Let's get your Q back to "as-new" condition, and you won't have to worry about "revving" on people at stoplights (which is incredibly juvenile, especially in a Q45).

Yes, one must NEVER consider mods (not even for a second) until perfection in its stockness is achieved.....

[maxnix]

Please don't street race anyone.

This scenario is almost as absurd as it gets. Let's get your Q back to "as-new" condition, and you won't have to worry about "revving" on people at stoplights (which is incredibly juvenile, especially in a Q45).

Yes, one must NEVER consider mods (not even for a second) until perfection in its stockness is achieved.....

Thanks guys!

I feel like I have been on a really bad trip and marooned on a survivors-form-hell fantasy island for the last several weeks.

[PoorManQ45]

Let's get your Q back to "as-new" condition,

I don't want it in "as-new" condition. I am making it "better than new".. I have kept the Q in very good condition. All synthetic lubes, including oil, transmission fluid, brake fluid, and differential fluid. I change the oil at ~3.5k, or 4 months. Get the engine flushed every year. I change the transmission fluid evey 15k~20k miles, and drop the pan every 50k. It gets completely flushed every year, along with oil flush. The brake fluid gets changed every time I change the pads or rotors 6~12months(usually unnecessary, but I change it anyway.) using sythetic DOT 4. I change the differential fluid every 30k miles(usually doesn't need it, but I do it anyway.) It's always been fed super-premium, with the occasional bottle of octane booster here and there. Fuel filter gets changed every 5k~10k miles. The timing chain guides along with the chain were replaced at 50k miles, by the original owner. I have replaced the radiator(old one cracked) with one that is a little larger than OEM. I have replaced the water pump, alternator, fuel pump, shocks and springs, power-steering pump, and a few bad bushings. And a few other things that I can't think of now. I would say that is a very nice maintenance schedule.

There were two owners, prior to me. First owners were a 70year old couple, with money. They followed the maintenece schedule very strictly and then some. They are the one's that had the chain and guides replaced. The second owner was a ~40year old couple. The man worked at Nissan. He had a maintenance schedule very similar to mine, maybe a little bit tighter.

So, as for the comment about getting my Q45 to "as-new" condition. I think that I'm doing a good job. Is there anything that I missed in my maintenance?

Please don't street race anyone.

Besides the legality, what is the problem with doing this?

... and you won't have to worry about "revving" on people at stoplights (which is incredibly juvenile, especially in a Q45).

I would be revving the engine to get them give a little more respect(growling exhaust usually command respect) Have you ever heard a car with straight pipes. I wouldn't even need to rev the engine. The exhaust would be very loud at idle. At about ~2k RPMs is when these exhausts start to get extremely loud. So, even if I did rev the engine, I wouldn't have to rev it very high to make my point.

Ok now. Back to the subject. Would there be a benefit from the system with the electronic bypass valves that I described? So far, I like the idea of having both a stock exhaust and a loud "free flowing" exhaust at the push of a button. To solve the problem of low-end torque loss, couldn't I start going with the stock exhaust, and at the point where the stock exhaust becomes restrictive, I could open the vavles and dump the exhaust.

[pito11213]

Wes define perfection. I am sure before your Q died you felt it to be in perfect condition (explaining the price you were asking.) You must have been pretty sure that the Q was in "perfect condition" to abuse it on straight WOT runs like that.

Why is this exhaust question so incredible? Thank God that the guy working on transmission decided "hey why cant I have 4 gears, 5 gears and dare I say it 6 gears."

I understand the Dennis is the foremost word on the Q45 but does that mean we simply exclude anyone trying to do things out of the norm. There was a time when fuel injection was considered weak.

Come on guys surely we can do better than this when it comes to a simple question.

[maxnix]

Why do I keep hearing the intro for The Twilight Zone?

Please make it stop!

[pito11213]

max just turn down your tv when watching the show

[louiegz]

New ideas are good, but no one agrees with poorman. If he feels so strongly that his idea will work, then try it, let us know if it worked out. You cant expect other people in this forum with many years of practical experience to change their minds without proof.

[pito11213]

come on guys lets act like NICO Supporter

[pito11213]

but that is just itHe isnt asking for anyone to change anything.

He is throwing things out there to get the great minds of nico jumping

Lots not forget when the Q was introduced it wasn't a practical car at all.

[rydwhite]

Hmmm, it is an interesting thought in theory at least. I don't know much about the Q's exhaust system, but it does sounds at least plausible to working. Would it work? I don't even want to venture a guess. It seems that the trials of engineering and testing might make it more costly in the long run though if it doesn't work.

[PoorManQ45]

Could you please explain what your refering to.

If you think my ideas are stupid, just tell me that they are stupid. When you do this, please provide an explaination as to why you have this opinion.

[PoorManQ45]

New ideas are good, but no one agrees with poorman. If he feels so strongly that his idea will work, then try it, let us know if it worked out. You cant expect other people in this forum with many years of practical experience to change their minds without proof.

Noone has agreed or disagreed with me, that is the problem. If you don't think the exhaust modification that I am talking about, please just tell me. And have the curtiousy to explain why you think it won't work.

[Jesda]

Hell, I say go for it. If it works, youre a pioneer. If it doesnt, we can learn from it. Plus it doesnt hurt me or cost me a dime, as long as you arent doing anything unsafe.

-Jesda

[PoorManQ45]

wow, thanks for the support pito.

[elwesso]

Allow me to clarify something... I might not have made this clear...

I have NOTHING against this modification!! NOTHING! I think its a great idea! If he's doing it cheaply, then go for it..... Id much rather see him chop off the rear resonator and putting some bling bling chrome pipes.. WIll be loud, might vibrate a lot, but it will be cool! Again, let me re-iterate.. I have NOTHIGN against this mod! I was going to do it on my Q this winter, but now it looks like I'll be doing it on other cars!

What I dont like is the idea of jerry rigging a dump valve, that will probably end up melting away or something... And cause MORE problems... IMHO dont mess with aynthing past the foremost resonators.. Hell, chop those out and have the straight pipes... Be loud as hell, but who cares!

[pito11213]

The dump valve doesnt have to be jerry rigged. It would have to be created and placed creatively though considering the space under there. I think that PMQ wants the same setup that alot of the chevy and ford guys use on their muscle setups. It works just like he said press a button and a flap inside directs exhaust from the stock system to pipes coming out the bottom.

[pito11213]

Sorry if anything came out hostile but it becomes old when every idea outside of normal thinking is simply shrugged off.

[DAEDALUS]

Noone has agreed or disagreed with me, that is the problem. If you don't think the exhaust modification that I am talking about, please just tell me. And have the curtiousy to explain why you think it won't work.

You don't really provide enough details to say whether it won't work. Oh, sure, electronic valve on the exhaust, a little plumbing, some electronics, $50, and voila. How about some vendors and part numbers for these valves that we can look at and judge? Some of us, including me, have never seen one. Wanna do it yourself, fine. How about a functional sketch of what you intend to do, with a good idea of materials (again with vendors, specs, etc) and processes? No one will have all the answers for you, but you provide very little to go on. You have all these grand goals in your head but not many details. You just post your ideas and ask why it won't work; from what I've seen you ignore any answer you don't like.

The smallest through-way crosssection area in the valve will have to be at least as large as the exhaust tube or you won't be reducing the restriction. Don't forget to factor in the effective restrictions on every transition, bend and curve; i.e., each xx* bend is equal to the restriction in a straight pipe of y feet. I think 90* is 9 feet. Simply going over a weld bead will increase the restriction.

[PoorManQ45]

You don't really provide enough details to say whether it won't work. Oh, sure, electronic valve on the exhaust, a little plumbing, some electronics, $50, and voila. How about some vendors and part numbers for these valves that we can look at and judge? Some of us, including me, have never seen one. Wanna do it yourself, fine. How about a functional sketch of what you intend to do, with a good idea of materials (again with vendors, specs, etc) and processes?

Do you not understand that this is only an IDEA right now. Here are a few sites for you to "judge".These sites are a little pricey. But they give you an idea of what I'm talking about.

http://www.dmhperformance.com/ecutout.h ... xhaust.htm

I'll post more later.

You just post your ideas and ask why it won't work; from what I've seen you ignore any answer you don't like.

Not true at all. If people post answer to my question, they shouln't just say, "That won't work. That's another stupid idea. etc..." If they were to explain there answers a little better, I would pay a little more attention to there answers.

The smallest through-way crosssection area in the valve will have to be at least as large as the exhaust tube or you won't be reducing the restriction. Don't forget to factor in the effective restrictions on every transition, bend and curve; i.e., each xx* bend is equal to the restriction in a straight pipe of y feet. I think 90* is 9 feet. Simply going over a weld bead will increase the restriction.

Thanks for the info.

[DAEDALUS]

If all you want is louder exhaust then certainly that will work. I would wager that you will lose power with it closed versus your current stock system. Whether you will gain or lose power with it open you will just have to see. I think you would lose some down low and gain some on top, meaning I think it will hurt you off the line unless you really abuse your car.

[PoorManQ45]

here are some more links.

http://www.installuniversity.c...n.htmhttp://streetpro.us/HowItWorks.htmlHere's a drawing http://filebox.vt.edu/users/mi...m.jpgh ... nc...r=361+ http://www.mccordcg.com/mpp/mpp.htm

Not related but good links.

http://www.automotiveforums.co...20125(gives cost of modifying a VH45DE for boost)