I'm tired of every website having a different spec v quarter mile time... I'd like to hear the average quarter mile time for stock the spec v. I would also like to hear good times with the stock spec v. Also, how does this compare to other competing cars such as the eclipes(new and old), celica, rsx, cobalt(non super), tiberon, etc... Let's get some personal facts going on here, not what specplace.com or nissan says.

ive run 9.85 in the 8th mile as my best back when it was a stocker, not sure how that matches up to quarter times, kinda hoping it squeaks in under 15

ok spec-v versus

cobalt? spec wins
non-turbo older eclipse? spec wins
turbo eclipse? eclipse wins
new eclipse? spec should win
celica? close but id say spec wins
rsx? close but spec wins
tiburon? not sure, but judging its weight id say spec wins

keep in mind that all these are according to exactly equal drivers
ive seen a bone stock SRT-4 run 13.9, and one run 14.8
bone stock s2000 run 15.5 and one run 14.2
bone stock wrx STi run 14.6, and one run 13.3
ect ect ect

some people really dont know how to drag race

Spec-V = 15.4
Cobalt SS = 15.0
Eclipse GS-T/GSX = 15.0/14.9
Celica GT-S = 15.6
Tiburon GT V6 = 15.6
RSX-S = 15.0

These are all AVERAGE!

I've seen a Spec run a 14.9 stock, and a Celica run a 16.0 stock. Average. I mean, I took a modded Prelude SH in my Maxima all the way up to 100mph. He shoulda killed me if he knew how to drive. But yeah, the Spec is one of the faster compacts.

Why does it seem like it is so slow? Everywhere I look on reviews and what not they say things about how the spec may not be slower than this car or that car etc. but "hey it's good for the money". All people ever say about it is that the car runs good... for the money and that it's not really faster than other compacts out there. I just don't get it. And the more I research my car the slower it seems and the harder and more pointless to mod it seems. Why is the picture so distorted? I've heard of people with cia and maybe one other mod running high 14's, yet the guy that wrote an article on specplace.com said he had 3 things done to it including upgraded suspension and his ran a 14.8 in the quartermile! He put 2 grand into the fucking car! Now were his mods really shitty? One minute people have me thinking that a cia and one other small mod can get me in the 14's and the other people say that you have to put 2 fucking grand into the car to run a 14.8! Okay here is the deal... nismo r-tune cia and a high flow megan muffler... What do you think that can do for me quarter mile wise??? I think we all need to get a clear picture at just what and what not the spec is capable of. Thanks, guys.

Don't get discouraged because someone else doesn't know how to drag their car. Also, spending 2g's on intakes and exhausts is a waste. Here read this thread for all the answers.

http://www.automotiveforums.com/vbulletin/showthread.php?t=451934

focus on improving your racing skills and you will see times fall for free......like i said ive been practicing really hard and doing the math im pretty sure it gets there around 15 flat prolly a little less, the spec hauls dude

dont get megan racing please. im trying to make that rice company die off but i cant do it alone.

get hotshot headers/nismo, hotshot, or aem intake/jwt(cams, ecu, balance shaft removal kit)/any decent exhaust(pls not megan)/and some tires

and after this 2-3k you should be low 14s

dont get megan racing please. im trying to make that rice company die off but i cant do it alone.

get hotshot headers/nismo, hotshot, or aem intake/jwt(cams, ecu, balance shaft removal kit)/any decent exhaust(pls not megan)/and some tires

and after this 2-3k you should be low 14s
What is wrong with megan?

they are a stupid ricer company who makes cheap crappy parts. one step up from APC

I say screw the exhaust all together until the very end. It might make your car sound different, but the gains won't be THAT great(3-8hp). Get much more hp/$ in other mods like an ECU or flywheel. Plus, a short-ram intake is where the sweet sounds are at.

will a newer stock prelude take a spec?

yes

no as long as you get the whole exhaust system with the headers and everything its a good bang for your buck. It also depends if you ever want to run nitrous or a turbo its a good first step

Oh yeah, exhaust makes a HUGE difference with turbo. But for just a bolt-on Spec, I'd skip the exhaust till last.

celica gt-s 16s? it must be what year you're talkin about. my neighbor has a 2001 and it runs 14.8 stock @ the great lakes dragstrip. i kno that megan racing products are crap, but what bout OBX, ive heard their crap too, the hearders crack. what other companies should he stay away from if you kno of any.

I said a 15.6 average. AVERAGE!! plus I don't believe you

I've seen a spec run a 14.9 at the track with intake exhaust AND a passenger so it's definantley all driver.

celica gts is slower than a spec dude, maybe the driver was like warren johnson or something but ive never seen a stock gts run fatser than a spec

who said it was faster?

I have a friend with a specV he runs on average 14.5 with very little mods, and thats in hot/humid/shitty track conditions with stock tires. (dont know the mods exactly but I'll find out if you ask.)

but like all of you are saying, driver skill is a big difference, I'll admit Im not a very good driver. On average I get 14.5's out of my civic, I let my friend with the specV drive and he gets 14.3's. At the same 95mph which hints that the .2 was all driver :uhoh: (yeah, I suck). Actually I dont suck, he just happens to be a very good driver. A big group of friends let him drive their cars to see better times out of their cars!

idk, i guess its all driver, he's not a warren johnson o n e thing, but all he had was a CAI when he made the run to my knowlege. i dont wanna start getting flamed on..geez.... i dont think a CAI would really make the car be that much faster, maybe like .1 or .2.....

Well, it also depends on the mods. My Classic SE-R has 3 mods and dropped the 1/4 time by 1.1 seconds. There's a lot more to racing modified cars than the actual racing. You have to know your engine and what mods will get you the best results for your money.

oic, that means research on your engine a lot, unless u kno it really well. i thought that u gained a lot more power if u could bring in more air and let out all that it wants without backpressure?

oic, that means research on your engine a lot, unless u kno it really well. i thought that u gained a lot more power if u could bring in more air and let out all that it wants without backpressure?
no backpressure is bad. But you have the idea. More air is the name of the game. The reason you want more air, is so you can burn more fuel, more fuel = more power.

it is waaaaaay more complicated than that but basically yeah air+fuel=power. increase in fuel will only add power with increase in air, but your cylinder head is really what limits air intake.

!!!!restriction and backpressure dont let in or release less air, it just makes the engine work harder to get that same air.!!!!!

when you get serious into tuning, a wideband o2 sensor will be your best friend. A/F ratio is the most effective way to tune your car.

Which is EXACTLY why you shouldn't even be working on getting more air into your engine anyway. Your money is best spent on other more effective areas.

it is waaaaaay more complicated than that but basically yeah air+fuel=power. increase in fuel will only add power with increase in air, but your cylinder head is really what limits air intake.

!!!!restriction and backpressure dont let in or release less air, it just makes the engine work harder to get that same air.!!!!!

when you get serious into tuning, a wideband o2 sensor will be your best friend. A/F ratio is the most effective way to tune your car.
actually reducing restrictions will allow more air in the engine. Your right about the engine working less to get that air, but it will also allow more air in. Since air is compressible when the intake valve opens air doesnt flow in as fast as the piston goes down. when the piston goes down it creates a vacuum and then air comes in. With less restricions more air will have flown in before the valve shuts again.
and still, like you said, it is a little more complicated than that.

although no restrictions are a good thing for intake, you need to have backpressure for optimal exhaust speed. Having the perfectly sized piping will allow a balance of high-flow and airspeed, the perfect balance is what gets you the most HP.

so you mean the 10 inch exhaust piping i just bought wont give me more power than your 2.5 inch piping?

theoretically, the only reason to get a smaller exhaust is to make full use of the scavenging effect of the headers, ect.

i have yet to see any proof that backpressure is needed at all for power...and i have seen dyno pulls on nearly stock hondas, ect. with nothing after the headers and power + torque is gained over a cat-back through the ENTIRE powerband

driveability is another issue. with no backpressure your car will run rough at idle.

what is the ideal piping size for the spec?

2.5 inch NA.......3 inch FI

will a newer stock prelude take a spec?

No a newer Prelude cannot take a SPEC-V I had an Lude thank you, and the Spec-V is up on it. There is another post on here as well that goes over it and there is a concensus of about 18/20 people that the Spec will take the Prelude.

http://www.automotiveforums.com/vbulletin/showthread.php?t=99270&page=1&pp=15

Sorry, just aint happening. The Prelude has nearly 50hp on the Spec, a redline that's nearly 2000rpm higher, and super SUPER-short gearing. It's a FACT that 1997-2001 Prelude SH's run a 15.0-15.1. A stock Spec is almost half a second slower. If anything, the Spec would have the Prelude through most of it's first gear and that's it.

then why did my stocker V crush a 99 lude with intake and exhaust, hondas make their power later in the band, by the time he shifted out of first i was already halfway through 3rd and pulling, that extra 50hp isnt made until higher in the band where i was already gone, it might take the spec from a roll where he would go right into peak power but other than that the lude loses dude. if the prelude made that power earlier in the band he would have stood a chance.



(before the flaming begins yes he knows how to drive, i taught the dude how to drive and he shifts exactly like i do so there isnt too much driver error)

First of all, this is the H22 were talking about here. Not a B16. The torque curve on the H22 is VERY similar to the SR20VE's which is almost completely flat.

Second, there's no way you were going over 70mph by the time he barely got to 35mph. There's was something really wrong with that race.

Third, your story reeks of total horse crap. The Spec is an awesome car with a lot of potential, but it's not to be put on it's own shelf and be called invincible. Shit, a 1996 Buick Regal or an '89 Ford Taurus sho could beat a Spec. The Spec only bests a 138hp Ford Escort ZX2 by 0.3 in the quarter.

With all respect the escort only has 127hp for the GT had one of those. The prelude does have about 200+lbs on the Spec-V, and approx 20 hp, but lacks about 20lbs of torque too.

Just the numbers alone there says the Spec-V will win.

An extra 200lbs with only 20xtraHP and 20lessTq

Sounds close, but sounds like the Spec-V will win
Now to my knowledge this isn't the SH i don't know too much about it, but i know based on the SI Vtec H22 motor in it. I feel the difference. I just bought my Spec-V, and I got rid of my prelude last year about this time. I can't directly place the feel of it, but i can say. I feel as if i have a noticeable feel in the Spec-V than the prelude.

If you would like i will hit the track with my friend. He's got the 00' Prelude

yes, but the only power you can FEEL is torque. You can't feel HP. It creates more of a "floaty" feeling than a pulling feeling. You're also forgetting of the MAJOR advantage that gearing provides. A Spec redlines at 6200rpm@38mph. The Prelude reds at 7800rpm@35mph. That's nearly a 2000rpm difference at the same speed meaning that the gears in the prelude are incredibly short. Shorter than even a B13 SE-R's. Now a weak power curve(if the H22's WAS weak), would only matter in 1st gear anyway. But since 1st is so incredibly tiny, it flies to redline before you know it. Smaller gears make the car seem dramatically lighter to the motor.

One thing I will say though, I'm sure the clutch and the low-end power in the Spec are better. It will definitely have the initial launch. But here's where things get tricky...the Prelude is meant as an "entry-level luxury car". If the Prelude has a terrible start, it won't catch up. Whereas the Prelude's 1st and 2nd gears are super tiny for around-town acceleration, it's also missing a gear to the Spec's 6-speed. The Spec is geared just like any other compact until 4th. 4th is a real small gear on the Spec and will pull HARD. I would actually be more inclined to believe the Spec winning from a roll or passing the 'Lude farther into the race(despite the trademark VTEC top-end), but not spanking a 'Lude in the first 2 gears.

I think we can agree on that, I'm not saying a Spec-V would spank a lude, as i refer to it as. But I think it would take it. And yes those High RPM's matter alot, but if you can really run through those gears on the 6 speed it well compensates. It is a tough match on paper, and in reallity, but i'll stick to my guns on the Spec-V, but a good argument either way. I think we could agree that much?

Definitely good argument.

My voting in a race would be like a 60/40 - Prelude/Spec. Tough call. Especially when I remembered that the Preludes don't have 220hp. :D

Your thinking of the famed but rare as hell H23 Vtec in the JDM accord wagons. They got 220, plus if you put the ingenuity to it, and frankenstein the H23 block to the H22 head you get that HP too. Honest mistake man.
I'm not so much of an ameteur. I just am not as well versed as everyone else. I normally do a hell of alot of research on what i want before i buy it though.

Naw, I was just thinking of a plain old 3rd gen Prelude. The number 220 was just stuck in my head for some reason. Never heard of the vtec H23, tho. Only the old 2nd gen 'lude's 160hp H23.

Ah, well being that I had a prelude, I had to be an enthusiast, and i got ito some deep research about it. You know how rare Accord wagons are. Not alot of them running around. So in Japan even less, and they carry the very powerful 220HP/167+lb H23 VTEC engine in it. Hard to find one at all. So most people make them by frankenstein the two, of corse you have to make additional oil ways in the block, and your good. Trust me I know my Ludes
hehe

have you ever driven a spec fugiot? granted i respect your opinion on things much more than anyone elses save slideways, but the spec pulls like a down syndrome patient at any speed over 65mph, also half way through 3rd puts me at about 55mph not 75......as for the h22, yeah its nice, but ive beaten one dropped into a crx hatch with intake, that motor is nice but not nice enough, and yes i know the spec gets beat by plenty of things, hell ive been pulled by a damn vibe gt from a roll, (we were doing about 80 though and i already told you about the down syndrome thing), drag racing is about initial acceleration anyways, ever watched a pro drag? they make 80% of their top speed before half track, the more power you put down earlier in the race, the better your chances of winning, hondas are not made to be drag cars. Period.

Yes, I've driven many a Spec. While I agree that it does have good high-speed acceleration, the point I was arguing was stomping a Prelude SH by 40mph in the first 8-9 seconds of a race. Also, there's something wrong with your spec if you aren't doing about 55 at the end of 2nd gear.

my point was that the spec's high speed acceleration sucks, only chance from a roll is 45 and drop 2nd, or 65 and drop 3rd any higher and you get toasted by mommies minivan.......3rd gear speeds are from 50 to 70 halfway puts me at about 60 or so, so id really only have him by 15mph in the first 8-9 seconds.............:thefinger: lol i love my smileys

So if your 3rd gear only takes you to 70mph, why would you drop into 3rd when you're going 65mph?

By the way, I was refering to this statement
then why did my stocker V crush a 99 lude with intake and exhaust, hondas make their power later in the band, by the time he shifted out of first i was already halfway through 3rd and pulling...

60 - 35 = 25. Seriously...you can't beat a Prelude that bad in a Spec if both cars were actually racing.

i think you rate the spec's time a little low too dude, i was pushing about a 15.1 before my MMI and light rims and short shifter, i havent been back since but im sure it will be sub 15, as for exact gear measurements..... i dont remember EXACTLY what mph/rpm i was at, id honestly rather be looking at something more important.....lets say, the road. im familiar with my car enough to know where its at in the powerband and i can associate that with a speed, forgive me if im a few numbers off, but i pulled that prelude pretty hard. take it as you will but i know all drivers are different, maybe get someone else in that dirvers seat and take me down?




:useless:

and youd hit 3rd to get some forward momentum going, if you go straight to 4th you bog down too far, dropping 3rd puts you at about 5500 rpm making for a very short gear but you will have some forward acceleration to help bump you up in the rev range when you shift to 4th thus keeping you higher in the powerband where all that mad JDMtyte power is

Well, you said you "trained" the 'lude driver yourself. I don't think it's unbelievable that a Spec beats a 99 Prelude. But halfway thru 3rd when the Prelude is just finishing 1st? rrrriiiighht.

and youd hit 3rd to get some forward momentum going, if you go straight to 4th you bog down too far, dropping 3rd puts you at about 5500 rpm making for a very short gear but you will have some forward acceleration to help bump you up in the rev range when you shift to 4th thus keeping you higher in the powerband where all that mad JDMtyte power is


Yes, but a point you've so strongly defended yourself was...the Spec is all about mid-range torque. It would be much more effective to drop into 4th if 3rd gear really does end at 70mph(which I still don't think it does). You'd be wasting time with 2 shifts to gain a mere 5mph in a weaker part of your powerband.

its not the power in 3rd im talking about, its the fact that when you shift into 4th you will be X-rpm's higher (dont have an exact number but for the sake of arguement ill go try it here in a few and get you an exact figure) when you shift to 4th at 65mph it puts you below 5k rpm where you lack some of your power, shifting to 3rd first puts you above 5k and your intake rnners will already be open when you let out the clutch, shazaam, instant power

Yes, I know, but you'll only be gaining 5mph. Which is a waste of time for 2 shifts. The meat of your power is right below 5Krpm anyway.

from a roll your first shift doesnt matter, youre both going to pick a gear, i dont let off the gas to shift anyways so the difference in timing is negligible at best.........to put an end to this im going to time my 65-80 speeds using both my method and yours and we'll see, the only reason i shift the way i do is due to preference, and what i think works best for my car, but if your way works better maybe ill just go ahead and call you right..........

So my friend beat me from a roll with his Chevy SS extended cab pickup and I about shit myself... He Barely pulled me... I mean barely. I always thought I could take him from a stop... he hasn't done anything to this truck except exhaust and it's an auto. It blew my fucking mind. I think I can take him from a stop... what do you guys think? I mean cmon... it's a damn full size truck!

Haha, remember...upgraded exhaust systems are worth up to 40hp on a big V8.

thats no joke...it will depend on how well he launches, other wise its another story.

chevy SS.....couldnt tell ya, but if i kill one ill be sure to let you know....are you talking about the colorado SS or the silverado ss........i would think a silverado would kick your ass up and down the street, the colorado you should take though

It was the silverado SS. I hung with it the whole way, he just BARELY i mean BARELY pulled on me AND I missed third gear.

keep in mind I said extended cab, because I know a non extended cab can take a 350z

lol i was going to say, i thought the SS silverado was built to contend with the lightnings and srt-10 ram, didnt think there was any competition there..........i DID beat a srt-10 at the track once, my 9.85 to his 9.97........he didnt know how to drive though.....hahaha

!!!!!!!! DAMN WTF WERE YOU DRIVING? But I think the SS silverado runs a lower 14 in the 1/4.

lol my bad zach, that was in the 1/8th mile here at jax raceway park, i was driving the spec of course

i have yet to see any proof that backpressure is needed at all for power...
http://www.supertrapp.com/technology/index.asp

I had a friend who was very serious about atucrossing and used a supertrapp muffler to tune his car at a dyno. He didnt just use the muffler, but when he had the car tuned to his liking, he would get a few extra ponies here and there by tuning the muffler.

http://www.supertrapp.com/technology/index.asp

I had a friend who was very serious about atucrossing and used a supertrapp muffler to tune his car at a dyno. He didnt just use the muffler, but when he had the car tuned to his liking, he would get a few extra ponies here and there by tuning the muffler.


I'm not sure i completely understand the concept of the backpressure in this case, and how it will cause you any gains? Can someone explain that to me?

I'm not sure i completely understand the concept of the backpressure in this case, and how it will cause you any gains? Can someone explain that to me?

Honestly I dont even understand very well myself, it is actually more complicated than I care to understand. But I believe its something like this. suppose you have a mass of air coming out a 2.5inch pipe. and the same mass of air coming out of a 3.5" pipe. For the same rate of air, there will be more volume on the 3.5" but more speed on the 2.5" pipe. And at low rpm you want the air to move quicker than at higher rpm.... I dont know exactly, the first part is true about volume and speed, thats simple physics. the other part... Im not even sure if that is true but so Ive heard. maybe you should do a search to see if you find something. a have seen different explanations and they all make some sort of sense. I guess its actually a mistery and people make up their own conclusions :screwy:

I have heard other explanations like if you have ever run in one of those bikes at the gym that you can adjust friction. you can pedal pretty fast with the right amount of friction, two much friction and you get tired, not enough friction and it just doesnt feel like your doing your best. I DONT KNOW!!! WHY DO YOU MAKE ME THINK ABOUT THIS!?!?:banghead:

At high or low rpm the flow size is the same, but the backpressure is created if the outlet size is too small, and at higher rpms is trying to force the air out. That creates back pressure. What i"m not sure about is why you want back pressure. I guess i'm not to understanding of the optimum exaust size all together. I'm in a physics based engineering program, and have done some physics labwork on some of the issues. Like with that tornado thing.

Someone explain the reason why you want the backpressure please!!

cuz the backpressure will 'press' you 'back' into the lead.....i guess that wasn't a good explaination :)

you want backpressure because it forces your NA engine to work, turbo cars want no backpressure because they get enough of it from the turbines and anymore would create lag, but a NA car wants backpressure because it will keep the exhaust speed constant, if it free flows then the exhaust speed will vary, causing a change in vaccum in the exhaust tubing which will cause power to fluctuate, it does this due to wave scavenging, which is where a vaccum in the exhaust tubing pulls the exhaust out of the cylinders on their exhaust stroke, this frees up some of the enigines energy to make power in the combustion chamber and not have to spend it expelling exhaust gasses. so there you have it, backpressure will not create a huge difference but as a previous poster mentioned, it will help tune a few extra ponies out of an NA car.

you want backpressure because it forces your NA engine to work, turbo cars want no backpressure because they get enough of it from the turbines and anymore would create lag, but a NA car wants backpressure because it will keep the exhaust speed constant, if it free flows then the exhaust speed will vary, causing a change in vaccum in the exhaust tubing which will cause power to fluctuate, it does this due to wave scavenging, which is where a vaccum in the exhaust tubing pulls the exhaust out of the cylinders on their exhaust stroke, this frees up some of the enigines energy to make power in the combustion chamber and not have to spend it expelling exhaust gasses. so there you have it, backpressure will not create a huge difference but as a previous poster mentioned, it will help tune a few extra ponies out of an NA car.

Actually backpressure is always a bad thing. What you want is exhaust velocity. If you go too large on the exhaust, you exhaust velocity suffers. I would go find the physics formula for all this stuff, but I am lazy, and unless anyone contests me, I will not spend the time. But at low RPMS you are putting out less exhaust, that is why if you go with the max recommended size exhaust (lets say 2.5 inch on a Spec-V) you gain HP at high RPMs where the velocity is at its max, but lose a little bit of low RPM power.

Plus, exhaust systems with no backpressure sound TERRIBLE. Just think of all those 1.5 liter Civics with 3.5" tubing. The air is practically falling out of the car making a farting noise.

Plus, exhaust systems with no backpressure sound TERRIBLE. Just think of all those 1.5 liter Civics with 3.5" tubing. The air is practically falling out of the car making a farting noise.
ahahahhaha :rofl: :rofl: :rofl: :rofl:
my new sig

rofl holy shite, beat me to it slideways

Actually backpressure is always a bad thing. What you want is exhaust velocity. If you go too large on the exhaust, you exhaust velocity suffers. I would go find the physics formula for all this stuff, but I am lazy, and unless anyone contests me, I will not spend the time. But at low RPMS you are putting out less exhaust, that is why if you go with the max recommended size exhaust (lets say 2.5 inch on a Spec-V) you gain HP at high RPMs where the velocity is at its max, but lose a little bit of low RPM power.
So the optimum exaust tubing is dependent on where you want your power curve? Like a smaller tube for more low rpm power, and bigger for higher rpm curve. So midrange will optimize high and low end power?

So the optimum exaust tubing is dependent on where you want your power curve? Like a smaller tube for more low rpm power, and bigger for higher rpm curve. So midrange will optimize high and low end power?

Speaking in general, yes, but I can only really answer that if I was able to dyno test all sorts of different sizes, but I can guess that 2.5 is going to be the best for a Spec-V. You might lose a little bit off your bottom end, but for your powerband you are getting the optimal size, and you could go bigger and probably get a better top end, but lose too much low to mid power to make it worthwhile.

I forget what car it is right now, I think the new Corvette, but there is one that has baffles that restrict the exhaust at low RPM's to maintain exhaust velocity, but open up at higher RPMs, so you get optimal exhaust size and velocity for the entire powerband.

so i should take my whole exhaust off including my header and ill see maximum top end right? or do i need that backpressure to make my car run right? :owned:

the only car you dont need backpressure on its a forced induction car, like i said they get enough from the turbine, but mild backpressure keeps exhaust velocity CONSTANT, which creates a continuous vaccum of exhaust leaving the pipe which pulls the exhaust out of the cylinders, if you use too big of an exhaust piping to eliminate backpressure exhaust velocity will actually be slower because of the volume of the exhaust piping, which is why you should'nt go too big, try removing your entire exhaust system and get back to me and let me know if you need a little backpressure or not. what you really want is the perfect size, just like fugiot said, that will create the greatest exhaust speed and lowest amount of backpressure, but you dont want zero backpressure because that will cause slower exhaust speed, catch 22 huh?

so i should take my whole exhaust off including my header and ill see maximum top end right? or do i need that backpressure to make my car run right? :owned:

It seems like you just want to argue with me here, but your not going to win, seeing as how you would still have backpressure, from a little thing I like to call THE ATMOSPHERE.

You can search it and every time you will see, the ideal exhaust has maximum exhaust velocity and ZERO backpressure. The reason a car runs shitty with a 3.5 inch pipe is because there is less exhaust velocity as well as zero backpressure. Lets say for a given car 2 inches is perfect at 3000 RPM's(since no exhaust is perfect at all engine speeds), it would have maximum exhaust velocity and no backpressure. If you were to decrease the exhaust size to say 1.75 inches you would get backpressure which WOULD PUSH THE EXHAUST GASES BACK TOWARDS THE CYLINDERS! and you would lose exhaust velocity. If you would go to say 2.25 inches, then you would still have no backpressure (GOOD!) but your exhaust velocity would suffer do to the larger exhaust size. You can use Bernoulli's equation to figure out why this happens. I haven't taken physics in 2 years now so I can't quite derive it out, but if you search I'm sure it can be done for you.

*edit* I should say however that all of this is in theory, in the real world you cannot eliminate all backpressure(ie atmosphere, pipe bends, etc...), but the ideal exhaust has the lowest possible backpressure possible (lets say 3-4PSI as apposed to 20-25PSI stock).

all exhaust is going to squeeze the gas some, unless you either remove your tubing or go with something like you see on a honda, you will have SOME backpressure, you just dont want a lot of it, i dont think this discussion is going anywhere though :useless:

all exhaust is going to squeeze the gas some, unless you either remove your tubing or go with something like you see on a honda, you will have SOME backpressure, you just dont want a lot of it, i dont think this discussion is going anywhere though :useless:

Your right, all exhausts are going to have some backpressure, but your argument that you WANT backpressure is flawed, which I was pointing out to help inform other board members that it is not backpressure, but exhaust velocity that is important.

but is it not true that SOME backpressure will actually increase exhaust velocity, its the perfect match of exhaust size and engine flow

you guys are just confusing me...i think imma pick up "cars for dummies" i get the backpressure thing, its just dumb to be arguing about....but w/e

but is it not true that SOME backpressure will actually increase exhaust velocity, its the perfect match of exhaust size and engine flow

Actually backpressure will never increase exhaust velocity, but having too small of a pipe for your top end will increase exhaust velocity for your low end, not because there is more backpressure, but because the exhaust velocity at low RPMs is better suited to a smaller pipe. But at high RPMs when your flowing much more exhaust, you will get more backpressure, which will hinder the velocity and give you less HP.

I looked into it and it is the new Corvette with the baffles in the exhaust that restrict the exhaust at low RPMs, this is not to cause backpressure, but to give it a small pipe at low RPMs to have maximum exhuast velocity, and when it opens up at high RPMs it is to minimize backpressure as well. Some Ferraris and Porsches have this as well, but I can't name any specific model.

I am not trying to argue here, its just a point that many people are confused on. Even I used to be confused on the relationship between exhaust velocity and backpressure, from growing up with people that worked on muscle cars, they tend to be the ones that spread the myth about backpressure.

Actually backpressure will never increase exhaust velocity, but having too small of a pipe for your top end will increase exhaust velocity for your low end, not because there is more backpressure, but because the exhaust velocity at low RPMs is better suited to a smaller pipe. But at high RPMs when your flowing much more exhaust, you will get more backpressure, which will hinder the velocity and give you less HP.

I looked into it and it is the new Corvette with the baffles in the exhaust that restrict the exhaust at low RPMs, this is not to cause backpressure, but to give it a small pipe at low RPMs to have maximum exhuast velocity, and when it opens up at high RPMs it is to minimize backpressure as well. Some Ferraris and Porsches have this as well, but I can't name any specific model.

I am not trying to argue here, its just a point that many people are confused on. Even I used to be confused on the relationship between exhaust velocity and backpressure, from growing up with people that worked on muscle cars, they tend to be the ones that spread the myth about backpressure.



almost...
everything is right except that
but because the exhaust velocity at low RPMs is better suited to a smaller pipe.

is sort of backwards. when gas at a constant volume and velocity is fed through a smaller pipe, the gas is compressed by the pressure from behind, speeding up the flow of the gas. sort of like squeezing a water baloon. it will try and flow out both ends but since there is more exhaust coming from the engine the only way to go is out the back. the analogy is more for effect and not for cause, since gas is highly compressable and water isnt. but compressing gas will build pressure, and the high pressure will want to go to the low pressure area behind the exhaust.