Cold air bends valves?

[guudasitgets]

So, that said, 25% more power is nothing.. in fact, my car has 25% more power just based on estimates from 0-60 times than it did stock. Counting my car's weight loss, I still say it's not quite 25%, but I'm sure I went from 92HP to around 115-120 at least, considering that I can beat a stock CR-X Si, but only by a few feet

So Christ you have a dyno to prove all this?

[Christ]

Nope, just standard common sense. If a CRX Si weighs ~1900 lbs, and has 108 HP, with shorter gears, and my car weighs around 1900 lbs also, is less aero, and has longer gears, I must have more power, considering that my engine is smaller than that of an Si, but has pretty close to the same torque curve in stock form.

The fact that I can only beat said car by a few feet, (~half car) tells me that I don't have alot more horsepower than that car, since we're both still sub-95mph in the 1/4 mile.

Based on that, I ESTIMATE around 115-120HP from my engine. Issue?

[Christ]

As far as proving that my car's engine could make 200 HP streetable, (a 100% increase in HP), well, use google. I don't feel that I should have to prove what others have proven so many times.

[some_other_dave]

Originally Posted by dichotomous

yes, especially for lower rpm torque, make the exhaust bigger.

Hmm?? Are you sure?

From what I have read about naturally-aspirated engines, making the exhaust primaries narrower and longer will help with the low-end torque. Narrower and longer pipes are better at promoting flow velocity, but worse for sheer volume of flow. And long primaries (how long? dunno!) can set up the resonance to better evacuate the chamber at lower RPMs than sort primaries.

There is also the effect of any secondary pipes after the collector for the primaries (if you're doing a 4-2-1 header), and of course that of the pipe after the final collector, but they get less and less important the further out you get from the exhaust valve.

Then again, this is all book-learning. And especially when it comes to fluid dynamics, reality can hold an awful lot of surprises that aren't in books...

-soD

[IndyIan]

Originally Posted by Christ

As far as proving that my car's engine could make 200 HP streetable, (a 100% increase in HP), well, use google. I don't feel that I should have to prove what others have proven so many times.

I should've said unboosted... 25% increase NA takes some doing on Honda's higher performance engines, using normal gas, etc. Intake and exhaust are not going to do get anywhere near that, even "chipped" it would be hard to get near that using normal gas.
A buddy had the civic si with the 160hp 1.6L, 100hp/L is very impressive!!! The car was fairly fast but its the 9000rpm wail that I remember.
Ian

[theunchosen]

If you are really looking to gain HP/MPG like as is said above the best method without touching the engine is to take the pipes run 4-1 then say3-4 feet from the engine total length of pipe chop them off.

Most cars that do this angle the exhaust to the passenger side(although if your exhaust ports are closer to driver side then thats adviseable) so it doesn't muck-up the underside of their car with soot. They manufacture vents that go onto the side(on the fender behind the wheels) so that the gases clear the car and avoid getting exhaust all over your paint. Although. . .the gases are accelerating for 18 inches outside the engine so, its safe to say as long as the pipe gets to the edge of the car the gases will clear your profile if the pipes are only 3-4 feet long.

[Vince-HX]

I would have to say a 4-2-1 design is the most efficient design due to less negative interaction between pulses that fire close together

Also if you look @ highly efficient turbo setups, they all use divided housings and manifolds. On a inline 4 the pairing would go 1-4, 3-2. And also on a turbocharged car the rule of thumb is go as big as possible on exhaust size to minimize backpressure on the turbine.

Mine is 3"

[Christ]

Going completely N/A on one of Honda's PERFORMANCE engines is a completely diff story...

I can get alot of power out of a standard fuel sipping engine without actually doing much.. most times, a cam, I/H/E combo will seriously open it up.

Performance engines on the other hand, are a different beast... engines like the F20C, which held (holds?) the title for most horsepower output per liter, are a tough act to follow, at least without swapping parts around from other engines, messing with compression alot, etc.

[Vince-HX]

imo all of honda's engines are performance engines, even our despised SOHCs

jdm d15b 3 stage vtec = 87 hp per liter N/A

And that engine also utilizes vtec-e and has the ability to be tuned to lean burn for afr's around 22-25:1 low load cruising for uber economy

If you want power you need to have forced induction, I/H/E aren't even worth it for n/a imo. Why spend all that money for maybe 25hp when for about the same price you can piece together a turbo setup that will double your stock number while upping the overall efficiency of your engine and allowing you to run longer gears.

And stock d series rods are fine to 250whp

[dichotomous]

Originally Posted by some_other_dave

Hmm?? Are you sure?

From what I have read about naturally-aspirated engines, making the exhaust primaries narrower and longer will help with the low-end torque. Narrower and longer pipes are better at promoting flow velocity, but worse for sheer volume of flow. And long primaries (how long? dunno!) can set up the resonance to better evacuate the chamber at lower RPMs than sort primaries.

There is also the effect of any secondary pipes after the collector for the primaries (if you're doing a 4-2-1 header), and of course that of the pipe after the final collector, but they get less and less important the further out you get from the exhaust valve.

Then again, this is all book-learning. And especially when it comes to fluid dynamics, reality can hold an awful lot of surprises that aren't in books...

-soD

right, I figured he ment soften the torque low down. thats what I was refering to. My car has slightly less down low torque now, at least I think, it drives smoother and pulls lower though, used to not have any ability to drive under 40mph in 5th (2,000rpm) but now I can climb hills at 30 in 5th (around 1,400-1500) so maybe its more?
but, I do have a full race header, very long primaries which are steped up along the way at specifice points, then longish secondaries (4-2-1). every tube is much bigger than stock though, which really uncorks the engine in the upper RPMS, the 421 and long primaries help with the midrange and lower, but they still arent as good as stock.

as far as dyno runs, no, I dont, I havent messed with the computer so I havent. however, there are many many people who have on my car with the same or similar mods done, and almost as a rule, raceheader/full exhaust/intake/no tuning will net you 150-165hp (depending on which parts you use and where you are driving[temps and such]) and with tuning it will jump to fairly constant upper 160's and mid 170's, though one guy got up to 180 with just intake and full exhaust with tuning. bone stock dynos usually end up 130-140hp (160 crank advertised). this is for the k230a3, the k20a2(orz1.z3) will go from 160hp stock to over 200hp (wheels) with those same bolt ons and tuning.