Whenever someone puts on a upgrade, there's always that theoretical 10-15 HP gain. Now does this HP gain add on to each upgrade For example if a G35 had intake (let's say 10 HP), exhaust (let's say 15 HP), and plenum (let's say 10 HP...would that be a 35 HP gain to the G35? or do they ALL work together to get an output of just a 10-15 HP gain?

 

No, the mods' separate gains do not add up each time you utilize one...That's called ricer math and that's not how it works...Once you start really modding your ride and you have several components that you are running the only way to find out the HP and torque gain is to dyno...You can't just add it all up...On top of all that, some mods will work better than others, and that's where research, other drivers' experiences, and trial and error come into play to get the most out of modding

"All the Power in the World resides in the Eyes..."

 

LOL "Ricer math"

Intake - 15hp
Exhaust - 10hp
Chip - 20hp
----------------------------
total 45hp
on car 325hp

Plus
N/A Blowoff valve - 5hp
Stickers - 5hp each x 10 = 50hp
30lbs rims - extra 5hp each x 4 = 20hp
------------------------------------
total 400hp on the car

It must be true according to the math! =)

- Don't argue with idiots. They will bring you down to their level and beat you with experience.=P-

 

One other things I seem to have noticed (can somebody confirm?) is sometimes they will rate the increase at somewhere other than peak HP, but use the largest difference. For instance, the mod adds 20 HP at a low point of the HP curve (160-180), but provides a meager 5 HP at high point (260-265 or 280-285). They then use the largest variation in claims. Thus the 'ricer math' thinks they went from 260 to 280, or 280 to 300, but really just increased max HP by 5.

That said, it all comes back to the dyno charts so you can understand where the gains are. Even then they can use two different environments to make the gains seem more. Grrr.

And that's when the forums come in handy.

2003.5 Sedan Black/Black w/ sport, premium, aero, and winter packages. See my profile for updated mods list and pics.

 

Does all this mean that we can spend over $2K for exhaust, plenum, ecu upgrade, CAI and get only net 15-20 hp at the wheel total? Isn't that a big waste of money? I don't know why I keep waiting for an exhaust system to come out for the sedan just to pay $1K for a net effect of probably 5 horses with my combined mods. Looks like the only true performance mod worth getting is a F/I.

 

Not necessarily. 3 different mods can add hp at three different sections of the dyno graph. One mod might bump performance at the low end of the scale, another at mid range, and yet another could bump peak hp at the top end of the scale.
I think that's why you can't just add them all together. You can't assume they'll all be effective at the same point in the rpm range.
I've invested about $1500 to $1600 US in all but the ECU upgrade and most of those mods were more effective at the top end of the scale for maybe a total of about 25 hp.
It's better than you think but not as good as the manufacturers would have you believe.
GSM

<font color=red>GSM</font color=red> <font color=black>Silverstone Coupe</font color=black>

 

That's what I'm saying. Best bang for the buck. Save up all the money and buy a turbo, Supercharger, or NOS kit. Then you will notice the night and day difference.


- Don't argue with idiots. They will bring you down to their level and beat you with experience.=P-

 

properly applying that power is another goal of modding. For a car like ours, tires can be one of the single biggest improvements you can make and tires can be had for much less than 1000.00 that will improve your performance.

other crucial mods are clutch and flywheel mods for MT's, valvebody upgrades (shiftkits) and torque converter upgrades for the AT's. LSD upgrades, brake upgrades, rear end changes (currently there is a 3.917 available to replace the stock 3.5)

You can do this on a budget too, but it takes time and DIY'ing.

Better Life thru Chemistry
Black on Black 03.5 Sedan 6MT - Custom Catback, Custom Intake Tube, HyperGround Kit

 

Even mods that may only increase a few HP at peak, but 15 or so in other points along the curve do gain you performance. Your engine doesn't do all it's work at that peak point.. it runs through a wide RPM range. Bringing power up in the weaker spots will improve your overall performance.

It's important to know that if you look at a dyno chart, the area under the torque curve is what's important, not the peak HP or torque rating. This is why a BMW 330i with only 225hp/214lb-ft can keep up with a G35 sedan with 260hp/260lb-ft. The bimmer has a flatter torque curve with, if I'm not mistaken, something like 90% of max torque is availabe from 2000rpm all the way to redline. So, even though the peak torque is lower, the area under the curve is about the same, since the curve is higher at other points on the chart.

2003.5 G35 Sedan Desert Platinum/Graphite Premium/Sport/Aero/Nav/Winter

 

DYNO is the only way to measure the gain with all mods. The most accurate is to dyno after each mod installed to see the real HP/TQ numbers. Most gain will come due to FI (forced induction), however the best gain would be due to all mods combined and engine management is the key.



2004 G35s (bone stock)
-----------------------------------
2002 s/c Accord V6
1/4 13.9@101.8

 

<blockquote><font class="small">In reply to:</font><hr>

It's important to know that if you look at a dyno chart, the area under the torque curve is what's important, not the peak HP or torque rating. This is why a BMW 330i with only 225hp/214lb-ft can keep up with a G35 sedan with 260hp/260lb-ft. The bimmer has a flatter torque curve with, if I'm not mistaken, something like 90% of max torque is availabe from 2000rpm all the way to redline. So, even though the peak torque is lower, the area under the curve is about the same, since the curve is higher at other points on the chart.

<hr></blockquote>

Concerning mods, this is the most informative post I have ever read. I'm a newb in this area, but what Ryo said made it clear for me.

To put it to an extreme, it's like the story of the tortoise and the hare. The tortoise (BMW) has the potential to win because it's slow and steady. Something like that.


2003.5 G35 Sedan 6MT Brilliant Silver on Graphite
Premium/Aero/Sport/Tints/Factory Chrome Rims

 

Peter006:
We have several areas in which we can work to improve performance on our cars.

Before we get started, let us be very clear together about one thing, and that is that totally stock, this car is truly outstanding performance for the price. The 6mt coupe with the 18" wheels and brembos is just an awesome platform through and through.

But what is even more remarkable, and why I bought the car, is that this car has fantastic potential above and beyond what it comes to you as....and that is special. You can modify it a little or a lot. And it will bring joy all along the process if done intelligently. It is one reason why I think that it is a true classic in the making. Time will tell.

1.On the engine. It is a pump. You can help it breathe in, and help it breathe out, and a variety of modifications will help you push the hp on this car up perhaps 30hp, maybe maybe maybe 40....and then you are pretty much done if you leave it Normally Aspirated ("NA") and do not take the block apart. Those mods are typically cold air intake tubes and high efficiency filters and the plenum on the intake side, (typically you can do most of that for a grand or so) and on the exhaust side the headers, cats and catback exhaust(typically you can do most of that for about two grand or so).

A new wrinkle is tickling the ECU for ignition and cam timing, the fly by wire control and raising the rev limiter, squeezing out a few more hp that way in addition to the above. (That will run you about $600-700 depending on what you do and who you go to).

If you want still larger horsepower gains there are two steps more you can go, and they can be combined
.
The first one is to change out the internals to racing specification parts, (cams, pistons, rings, rods, springs, valves) and do some polishing and porting to the heads etc. This will allow you to run higher revs safely, and also perhaps higher octane fuels, and you can probably get at least another 30-40 hp that way, and potentially quite a bit more. (It will be a noisy little beast though). But this is not cheap in labor or parts.

The second one is go with Forced Induction ("FI"), which is either with turbocharging, supercharging or nitrous injection.
The turbo and the sc are basically the same, turbines that compress and force air into the cylinder at higher pressures than normal, with more gas added, and you get a bigger boom in the cylinder. Conceptually very simple. The turbo uses the wasted energy from the exhaust to power the turbine, while the sc is belt driven off the engine. They both have merits and demerits, not for discourse here. On this car with the generally accepted present thinking, seven psi boost, give a return of about 45 to 50 percent more hp. So your crank hp will go up to about 400-420hp, or a gain of 120-140hp over stock. That is a LOT of power. More boost than that and there are early detonation issues with present set ups. Indeed there are early detonation issues now, but other threads deal with that.

If you combine internals and FI, you can go much higher still, probably to the range of 600hp before you reach the limits of pump gas as a fuel, and need to use very high octane juice to avoid detonation. (detonation is where the ambient temperature in the cylinder walls and the heat caused by the compression of the air/fuel mixture is sufficient to ignite the gas before it reaches top dead center and the spark from the spark plug, which basically will blow a hole in your cylinder or worse). Indeed with the racing fuels and additives you can start getting up to the world of 1000hp...and there are plenty of little Toyota Supras and Hondas around that have some insane figures...but you can't really enjoy them as reliable daily drivers, so for the moment, let's forget them.

So probably, for bang for the buck, FI is the answer if you can understand and accept the risks. With FI and some other mods you can get rwhp on this car to around 360-370 and crank hp at close to 450. But you have to take some informed risks to the motor to do that. If not your cup of tea, then pursue the basic breathing mods, and be happy with that. And if you really have gobs of money, you probably go FI and internals and some day we read about you in the papers having left earth orbit, possibly with the shift lever still in your grip, while showing an M3 your tail lights.

Again, please note, the exhaust on this car is darn good. Gains are limited from aftermarket products relative to what you may read about or be experienced with on other platforms partly because it is not garbage to begin with, so the additional results are going to be slimmer precisely because of that.

2. On the Drivetrain modifications. This is taking what you have and getting it through to the rear wheels more efficiently, and thus to the road. On a MT car the lighter flywheel and upgraded clutch are a classic improvement(Nismo/JWT/Tilton/EVO). It really helps a lot, because it allows the motor to rev more quickly, and that is great in coming out the turns, etc. . Another is the Limited Slip Differential upgrade. That helps get the power down right now. (Nismo and KAAZ). That really is not purely drive train, but also involves traction and suspension considerations. A short throw shifter (Rogue)might help a little bit too, (that is more like driver interface with drivetrain) but unlike some cars that have long sloppy throw shifters, the improvement on this car is only about 20% shortening of throw distance. It is an improvement, and it is not too expensive. It falls more into the category of just one more incremental improvement that in the aggregate of other such changes can help out materially for you. (and it sounds really cool to tell somebody you just put a "short throw shifter" into the car. Tim Allen would love it.) But again, while the shifter does not feel as precise and smooth as the Honda S2000, which presently seems to be one of my favorites, it is still pretty doggone good stock. And I suppose you can swap out the rear end final drive ratio to upgrade to the 3.917 from the 3.53 we have now for some better acceleration. I am still noodling on that one myself.

3. On the Suspension. This is very important, because this and the tires/wheels are what connect your car to the road. Sway bars, dampers and springs, wheels and rubber all combine. The sway bars stiffen up the chassis and reduce body roll(having tires pointed in one direction while inertial momentum is carrying your car forward in different direction is NOT a good thing), tires have grip but also sidewall roll considerations and you can improve both, better and more lightweight wheels will enhance the steering responsiveness by among other things removing the unsprung weight and also reduce the inertia that the engine has to overcome to turn or brake the wheels. The dampers and springs can work to lower your center of mass, and handle the substantially increased forces associated with throwing your car into turns at high speeds, (that is-higher than you would otherwise have done without the improvement)....and keep it under control....or at least right side up. And do not forget brakes. With the Brembos you have a set up that is really excellent. Probably do not have to do anything there unless you are really going to run it hard. Then upgrades are available, but they cost a bunch (like four grand or so for some 14" discs all around). (Ever notice how easy it is to think about spending four grand for more power and how hard it is to think about spending it for brakes? Think about it more.). This area can be quite complex, and if you do it wrong you can make the car worse handling not better, indeed even dangerous (so something as simple as drop the rear two inches and not the front, and put the wrong size tires and stagger on, and you will understand what "squirrely" means. If you survive. ).

But reconsider. What do you really want to do with your driving and what will give you pleasure and enjoyment?

The car already has a bunch of hp, with good torque. It has sway bars. And a viscous LSD. Great tires stock with the Michelin Pilot Sports. Great brakes. What are you really trying to achieve with your mods program. IF it is a few things that are fun and not risky and will give some bonus returns, and that is what most of us are after, then some intake and exhaust mods are usually the easiest. A good and relatively inexpensive suspension mod is to put some quality coilover spring kit in, for say $350, and lower the car an inch at the same time. Drivetrain is the flywheel/clutch hands down in my modest estimation.

But put in the upgraded lightweight flywheel and clutch, drop it an inch all around with spring coilover dampers, stiffer sways, and an LSD, and on a road race you should finish faster than your buddy that put the same money into getting 25 to 30 more hp, because you will be putting it to the road much more effectively, assuming you are equal skill drivers.

But if you want the hp "badge", that is ok too. They both are lots of fun. There is not a best way or only one right way. There is just "your way". If you think out what you want and why before hand, you will have a plan to follow and be satisfied with it all along the way, and that is what really matters.

Just ask lots of questions. Get all the facts and information you can. Get help from well qualified pros wherever you can. Encourage opinions from others...take them all with some reservation. Then you will not make mistakes...just choices with known outcomes.

Have a blast.


Cpe 6MT/Aero/Prem/ATI/RT cats/Borla hdrs-catbcks/Nismo flywhl-cltch/TS-ECU/Tein flex EDFC/Stillen sways

 

Eagle1 - let me be the first to thank you for your time. This is a perfect example of the unselfish spirit in which forums and their members need to benefit. Again, cheers to you!

2004 | 6MTs | Diamond Graphite/Graphite
Upstate NY

 

Excellent post- that's the kind of thing I like to see [img]/w3timages/icons/smile.gif[/img]

G

2003.5 Black w/ Willow G35
Premium / Sport / Aero / Winter / Navi / Tint