[nextlevel350z]

Good answers v1p3r, i'll add a few "- " below yours.

1] Plug wires? On a stock car, useless.

-Agreed. At least not enough benefit for you to actually notice.

2] Iridium Spark Plugs, 4 electrode plugs? Same as above.

-Agreed. Again, they do have some benefits, but not enough for you to feel, or maybe even see on a dyno.

3] Air filter/CAI?
colder denser air gives more power, how dense it can be ?? Useful, but CAI could get wet and damage engine in the rain. How dense air can get depends on location, altitude, season etc.

-Agreed again. But also, true CAIs suck outside air, while short rams and most stock intakes take air from under the hood. Even if it's 80 degrees outside, that is still significantly cooler than the air under your hood, hence, significantly cooler, denser, etc. A good CAI is usually a great bang for the buck. As far as damage/hydro locking your engine from sucking up moisture; many companies are integrating a bypass valve into their CAIs nowadays (AEM was the first to do it), so when/if your intake sucks in moisture (from a puddle, etc.), the intake stops sucking air from the main filter, and sucks it further upstream from a smaller, filtered bypass valve. Usually these intakes are a bit more pricey, but worth it IMO.

4] Lightened flywheel? Practically useless, since you will die in traffic.

-LOL! Agreed. It is a pain in traffic and daily driving, but if you are building a car for drag, it's well worth it.

5] electric supercharger?
supercharger is to make air dense, good for hilly region operation. airplane piston engines have supercharger for this reason Hahahahaha...this is the most useless.

-I agree. But in all fairness, I saw a magazine write-up on a product called an "e-Ram" - one of these electric superchargers, that showed a 9 whp gain on a U.S. Spec EX Civic. I couldn't believe it (it was from a reputable U.S. magazine, no less). I don't see how it's possible, but I thought I should mention it. Most of these "electric superchargers" I see ads for are made of plastic and are total garbage. Not only do they not add any power, but if a plastic piece comes off or the fan blows apart in your intake tube, say bye-bye engine. If anyone wants to do research on these, I would look at the e-Ram.

6] synthetic oil?
good lubricated engine with good cooling property can help in better life of engine than powerTrue, useful. But also expensive to an extreme for some brands. Whether it justifies the expense is debatable

-Certainly useful, but you probably don't need it on a car that is less than 5 years old. Once you start racking up the mileage, or your car starts to age pretty good, it's probably not a bad idea to switch to synthetic or semi-synthetic. Won't add any power (at least to a car that is functioning properly), but it could extent the life of your motor.

7] 97 octane fuel with octane boosters?
beter octane rating better power.Useless on a stock car. A lot of Indian cars perform better on regular unleaded.

-Very, very true. Higher octane fuel only helps if you are tuned for it. If your car only needs 87 octane, adding 92 is a waste of money, unless you get a tune/remap/piggyback that lets you take advantage of it. Also like to mention, octane booster is NOTHING more than higher octane gasoline (sometimes mixed with a bit of injector cleaner and other detergents). It mixes in an EXACTLY LINEAR fashion with the fuel in your tank already. For example, if you have 9 gallons of 90 octane, and you add 1 gallon of "100 octane booster," you will now have the equivalent of 10 gallons of 91 octane fuel. Seriously, you can check the math if you want - you are better off to just fill up with better gas at the pump.

8] TB spacers?
not for mpfi i suppose... for the carb muscle cars. Useless.

-Generally agree.

9] Strut braces?
handling Useful. But then you have to push the car or drive that fast to know the difference.

-Agreed 100%.

10] ECU reflash or remapping?
this should definitely exploit the full potential of engine, but loss of fuel economy. Depends on what you remap for. And I don't think you can get it done anywhere in India.

-Agreed. If you need/want to do something to account for i/h/e, you are better off with a cheaper piggyback, but if you are going to be doing a LOT of modding (more than just i/e, etc.), do the remap LAST. Any reputable company is going to need to account for your full mods list to give you the best remap. Do the remap last, unless you want to do it twice.

11] Low profile tyres?
great handling improvement at educed ride quality and more surface drag beyond a particular size? Also heavier, since the rim will be larger.

-Sort of agree. You don't HAVE to get different rims, to get a lower profile tire, especially if you only drop 1 series, or maybe even 2. Also, if you are going to drop to a very low profile tire, chances are, you are going to get aftermarket rims - in which case, you could also get a light-weight rim, that may actually weigh less than your smaller factory rims.

12] free flow exhausts?
this does help but cost a sound No it doesn't. An exhaust system is like a chain. Only as strong as its weakest link. The most restrictive part is normally the cat-con or the mid-muffler. You need a complete free-flow system with a well-designed set of headers to extract some power.

-Agreed about exhaust working as a system. To get the most gains, you need to do the whole thing, and it has to be the right size. Biggest isn't always best. You also have to look at overall gain. An exhaust that gives you an 8 hp higher PEAK gain on a dyno, might actually have less overall power (total area under the curve from idle to redline). Remember, you spend very little time at PEAK power - increasing total area under the power curve, is what makes you faster. If you gain 20 whp for 500 RPM range, and lose 5 whp under the rest of the RPM range, you are going to be slower, not faster.

13] high lift cams?
giving more feed to engine, hope it can eat it all without vomiting. Costs a load. You will need to fiddle with idle settings for days to get it right. Bye-bye, fuel efficiency. Low-end response will also die, if you get a wild cam.

-Agreed in general.

14)porting polishing?
whats this. Enlarging and smoothing the ports on the intake and exhaust of the head, to ensure better flow-rates. Helps.

-Definitely helps. Definitely expensive (at least in the USA).

15) reduce weight?
this will definitely increase power due increased power to weight ratio. And your car will bounce about because there is less weight to root it to the ground.

-You have to drop significant weight to affect how your car feels during normal driving - 50-100 pounds is a pretty easy "mod" we can all do easily (take out factory spare and jack, don't race with a passenger, etc.).

16) do not ice performance cars.you put in lot of weight with those sub and its box, amps. dampimg And again, your car will bounce about.

-Don't know about the bouncing, but it will definitely slow you down a bit with weight. Again, you are driving around likely 99% of the time, enjoying the creature comforts of your car. 1% of the time you are racing. Which do you enjoy more? Good tunes and nice ride 99% of the time? Or edging out the guy next to you 1% of the time. It's your call.

17)spoilers?
we do not have spoilers which provide any performance increase since all are bad design and fully cosmetic in nature. a inverted aerofoil structure should face the wind for providing aerodynamics many look funny but they work, it starts above 150kmph speed. Useless, unless you live on the autobahn.

-Agreed. Most cars can't go fast enough to take advantage of a spoiler. And if they can, they don't go that fast very often. And most spoilers are strictly for looks, and provide 0 (or very close to 0) in actual downforce, at any speed. Spoilers for looks, that's about all.

18)corner slammers and dtm slammers?
lighter cars tend to keep lifting of ground, these give downward force to help keep front wheel on ground. Never seen a car lift its front off the ground.

-Agreed.

Other mods you might want to add:

-NOS -> cheap power gain. Very risky, can blow motor easily if you overdo it (make sure you back timing off a few degrees!).

-Turbo/Supercharger -> High power gains, don't go more than 6-8 psi on a stock motor. If you want to go higher than that, get ready for a seriously $$$ investment in forged internals, sleeves, etc. Turbo will give you most power gain, even at same boost level over a supercharger, thought it will likely be a little more expensive. Could go on, and on, and on, about forced induction, but since this is a bolt-on thread, I probably shouldn't.

[v1p3r]

Originally Posted by nextlevel350z

14)porting polishing?
whats this. Enlarging and smoothing the ports on the intake and exhaust of the head, to ensure better flow-rates. Helps.

-Definitely helps. Definitely expensive (at least in the USA).

Half the cost of a camshaft here, or even less. Maybe you ought to look at outsourcing the process to us!

[nextlevel350z]

Hehe,

Not a bad idea...but I think FedEx/DHL/UPS would make sure that the price difference would even out ;-)

[chetanhanda]

Originally Posted by gigy

one thing about free flow exhaust......whats fact?

dude everything is not abt the dia of the pipe.
its also how smoothly u can take the gas out of the system and how fast.
reducing "back pressure" in "other words" is helping increase your exhaust velocity.similarly smoothly bent pipes help increase your exhaust velocity with minimum bends...
also consider cams into this picture, how cams + exhaust sytems influnce scavenging of ur cylnders...exhaust pulse and firing order of the cylinders... u cant just choose a fat dia pipe and not consider how ur headers are designed..?the length of primary and collector is also very very important

fat pipe = good freeflow system is just one of the factors (lets call the exhaust system for this discussion for our refrence as header,pipes,cat and muffler, if we take up header system here this will go very long,header design can be taken as a separate sub system in very detail)

Originally Posted by gigy

i have observed: the normal exhaust diameter chosen by manufacturer is sufficient for normal level of gas outflow in all normal operating rpms of engine

their normal is defined by what is easy and economical on the production line, easy to replace and mantain for a "non pistonhead" they do whats cheaper for them on the production line becoz they need to do it keeping the final price of the car in mind and the actual type of road use of the car.they cant afford to mandrel bend every exhaust sytem and carefully weld and polish the manifold for every car which is being sold for 4lakhs

I beleive that even the collector design on a manifold are selected by them based on how easy it is to mass produce them on a large scale than what is performance oriented for the engine..
Also we need to think that a normal "daily driver" for city conditions is going to see a lot potholes and bad roads in its lifetime.they need to think of this also when designing their car, so they carefully bend the exhaust pipe to pass over the axle and bend it back to meet it near the lower part of the bumper .. (see where Im getting at ?)
e.g the cat back or axle backs in some hi performance street/drag cars are below the rear axle. this results in straighter pipes without having to bend and pass over the rear axle, this is good for the exhaust velocity but u are screwed if you hit a speed bump or a stone from below.
even some perforrmace mufflers are so huge in dia that they scrape the ground when going up/down inclines in parking lots...
factory manufacturers need to consider these things when they design a car becoz if some person buys a car who is not a freak like us he will call it a badly designed car.

where Im getting is : normal design of a exhasut system is made for the general non tuner non car freak public, its not that the manufacturers dont know whats best for the exhaust design (look at any of the rally/track prepared cars by factory teams), its just that they cant give it to you for that price for daily use.. unless u buy something for e.g a "20 car only" production run handbuilt Nismo Z tune skyline R34... or some other exotic - Zonda etc ..

Originally Posted by gigy

its when you push in for more that the exhaust is not able to exit of the engine fast and could possibly builtup back pressure. here is where free flow helps, so freeflow puts in few more punch at higher rpm only when gas mass flow rate is high.
varoius dyno test results i saw on net confirms this. there is no change at lower rpms. the faster the exhaust can get out the better it is.
how do people claim increasing low end response or mid end response or tune exhaust?
i am learning

lets keep free flow terminology outside for a few minutes... and also consider cams and valves into the picture.
(there are other things but for simplicty sake for gigy to understand lets start with basics..)
exhaust system is designed to match your cams , your cam influences how u design your exhaust, u cant just say "Dude lets bolton a "X" cam with "Y" duration and then bolton a "A" header and a "Z" muffler coz the dyno chart in some mag said they make "X" makes 8 BHP and "A" makes 12 bhp and "Z" makes 5 BHP" so do the math : 8+12+4= 25 BHP Dude !! without understanding how they work with each other..
think like this--> is everthing they have is same as yours ? does the low end torque type of cam match with your "super Hi Flo ultralo back pressure exhaust system" match ?????
and lets back up a bit to the basic question..
what do you want ?
(a)low end, (b)mid range or (c)top end performance?
any of these 3 can be obtained by a freeflow exhaust system and combination of your cams.
in simple words your cylinder has explosive mixture which explodes at a optimum pressure and spark timing.
it works best a particular rpm band, you get good torque . But as you increase your revs you need to evacuate this gas at a higher rate.
this is where your exhaust velocity and back pressure can be explained.
now question is do you want power at low or mid range ? if yes then make sure the valves do not overlap to much i.e the duration the intake valve is open along with the exhaust valve.. as per "textbook" definition in a 4stroke the exhaust remains closed when the intake is open and vice versa... but in engine these valves remain open for a certain amt of degress of the camshaft together which is overlapping with each other... this overlap creates a scavenging effect pulling some of ur intake charge in to the exhaust.
dude what the hell happenned ? intake charge going into exhaust... ???

again in simple words this helps in mantaining your exhaust velocity, u see the gas is flowing much faster thru your sytem at higher revs due to this valve overlap... now if the exhaust system(headers, pipes,cats and mufflers) are optimised for this they will allow for low backpresure and quick flow of gasses thru your system.
But now the low end torques is lost as the intake charge is being lost due to scavenging but u get good BHP gains at higher revs..
if you want low end torquey engine choose a exhaust system which matches your cams with lesser overlap and more exhaust backpressure and exhaust velocity matching this setup.
so if u have a high rev power requiremenst go for cams with greater ovelap and a exhaust sytem which allows for greater velocity of the gasses to flow, consider this .. a narrower pipe would increase the velocity of the gas as compared to a pipe which is larger in dia for the asme pressure . e.g water flowing thru a narrow pipe, then coonnect a larger dia pipe and see the flow of water which is faster? .. the narrower one. so this doesnt mean you should use narrow pipes, what Im saying is "the dia of the pipe should be such that it creates best exhaust velocity for providing scavenging matching your cams ovelap"
if the pipe is too narrow/restrictive = more backpressure = lesser velocity ..ther should be a balance..

[ananthkamath]

more overlap on high performance cams isnt only for the effect you mentioned. The exhaust valve opens much sooner in the cycle to "bleed down" cylinder pressure faster so that less power goes towards the pumping loss on the upward exhaust stroke.

also, gas flowing through a smaller tube achieves a higher velocity and a higher pressure loss i.e. backpressure (how i hate that word), not lower. there are other resonant effects which affect header design in addition to gas flow.

you seem to have low regard for OEM exhaust systems. What you said may have been true 10 years ago, but now almost every manufacturer who cares enough about high specific power output (for eg Honda) equips the engine with a header-type manifold. Most OEM bends are quite well-made and do not have kinks or significant cross-sectional variations to impede flow.

[chetanhanda]

Originally Posted by ananthkamath

you seem to have low regard for OEM exhaust systems. What you said may have been true 10 years ago, but now almost every manufacturer who cares enough about high specific power output (for eg Honda) equips the engine with a header-type manifold. Most OEM bends are quite well-made and do not have kinks or significant cross-sectional variations to impede flow.

compare the DC headers and HKS mufflers with stock Honda systems..
are stock systems good as DC,HKS,ANSA,Pacesetter,Tanabe ?
or handbuilt custom exhaust sytems.. are OEM's that good ?

[chetanhanda]

Originally Posted by ananthkamath

more overlap on high performance cams isnt only for the effect you mentioned.

dude thats why I said this also clearly.. I know there is lots more..

Originally Posted by chetanhanda

(there are other things but for simplicty sake for gigy to understand lets start with basics..)

Originally Posted by ananthkamath

but now almost every manufacturer who cares enough about high specific power output (for eg Honda) equips the engine with a header-type manifold.

dude thats why I already said lets get into headers afterwards in a separte thread this is just an overview... see below

Originally Posted by chetanhanda

(lets call the exhaust system for this discussion for our refrence as header,pipes,cat and muffler, if we take up header system here this will go very long,header design can be taken as a separate sub system in very detail)

[abhibh]

Ok one question.

How do you guys calculate the power gain ? I mean how can you say that by installing K&N + Free Flow etc you have thing much gain in BHP ?

[gigy]

lot of new informations coming, thanks buddies
so an exhaust replacement will also call for cam shaft adjustment for proper power band. its not a bolt on!

[v1p3r]

Originally Posted by abhibh

Ok one question.

How do you guys calculate the power gain ? I mean how can you say that by installing K&N + Free Flow etc you have thing much gain in BHP ?

Dyno.

.................

[ananthkamath]

Originally Posted by chetanhanda

compare the DC headers and HKS mufflers with stock Honda systems..
are stock systems good as DC,HKS,ANSA,Pacesetter,Tanabe ?
or handbuilt custom exhaust sytems.. are OEM's that good ?

never quite said that. i said they arent as bad as you make them out to be. for the reasons you mentioned (cost, time for manufacturing) they cannot be as well-made as aftermarket systems (notice i said well made, not necessarily better).

Originally Posted by gigy

so an exhaust replacement will also call for cam shaft adjustment for proper power band. its not a bolt on!

not at all. its just that if you're bolting-on an exhaust, it needs to be matched with the characteristics of the stock cam. Unfortunately for us, most aftermarket manufacturers (except maybe a handful) still dont tell us what kind of cam the exhaust needs to be used with. It is upto us to find out (with a dyno, or an extremely perceptive driver, or both).

Ananth

[chetanhanda]

Originally Posted by gigy

lot of new informations coming, thanks buddies
so an exhaust replacement will also call for cam shaft adjustment for proper power band. its not a bolt on!

its a bolton depending on the level of tune of your car.. if you are not doing any crazy mods, u can just bolton a decent system to your stock car..

just keep that stuff in mind thats all before claiming BHP gains without a dyno..

[shibujp]

yeah..yeah..before anyone crucifies me let me explain myself...

As the adage goes "No pain, no gain"..the same argument applies to performance. The only things that are truely bolt on on a car are stuff that improves its appearance. Performance is a different aspect.

I agree that free flow exhausts, high performance filters and stuff do improve the performance but if you need the same level of trouble free and convenient operation as a stock system it involves a lot of work.

As has been mentioned on this thread an engine is a system, and the system has been tuned in a company. Now the minute you and I replace a component we are changing a system. So we need to do something or the other to get the system back into shape.

About stuff like ground wires and stuff i agree that by themselves provide very little gain but they sure do complement a system that has been modded for performance and improve the feel. Take a look at this site...SUZUKI SPORT Parts Information / SWFT. I understood only the graphs....here is the one for a street muffler...

News Release

It shows not much increase in bhp but the curve is much smoother.

Not withstanding this i do have a FF exhaust and a universal air filter in my car and am still searching for the feel i want.

Thats my two cents for now...

And for all the guys who have been putting in great info on this thread...chetanhanda,ananthkamath,v1p3r,nextlevel3 50z..etc..

- Shibu

[chetanhanda]

Originally Posted by shibujp

yeah..yeah..before anyone crucifies me let me explain myself...
Now the minute you and I replace a component we are changing a system. So we need to do something or the other to get the system back into shape.

right !!

Originally Posted by chetanhanda

Another topic which creates confusion...
you may have felt that the new mod is faster using ur seat of the pants
dyno.. OK agreed.
but you still may not be faster in the quarter mile/actual track becoz it may have just shifted the power band above or lower in the RPM range or must have created peak power at only a particular high RPM range which is unusable normal condtions.

you may be just moving the peak bhp/torque to somewhere else in the rev band, if you have done it right (without a dyno ????? ) and if you are lucky it may be accesible to you for regular street drving conditions say 2000 to 3000 rpm. otherwise it may move to some rpm band not used by you in daily situation say 6000 to 7000 then you will think "dude no power with my free flow and air intake". power maybe(I said maybe) there but it may be too peaky limited a very powerband at hi revs which maybe good for a "track car day" car going WOT .... and also will this so called gained BHP at this WOT condition be even perceptible to you ?? something to think abt.

or in some cases e.g of badly fitted,low quality piping intake sytem..even reduce the power output below stock level

[chetanhanda]

Originally Posted by ananthkamath

for the reasons you mentioned (cost, time for manufacturing) they cannot be as well-made as aftermarket systems (notice i said well made, not necessarily better).

sure !! ... not as "well-made".