info on ludes with how to mods
 

sorry about the whoring just posting some helpful stuff trying to make up for earlier :-\ .heres some stuff i found just trying to help out fellow lude ownerns out there :-*


Flapper Valve Mod
All Si and VTEC Preludes have a dual stage intake manifold, similar to what twin cam B16 and B18 motors have. Why the H23 Prelude motor has it is beyond me cuz the two stage manifold is usually part of the VTEC system. A normal manifold has 4 runners, one for each cylinder(on a 4cyl). The dual stage manifolds have 8 runners in the top two sections. At low rpm's, only 4 of the 8 runners are "open" and at a certain rpm, a set of flapper valves opens up to allow more airflow which results in more hp. Why don't they just have all 8 runners open full time? Simple, too much air will result in a low end power loss. So until ~4800rpm
you have 4 runners open, then at 4800 a set of flapper valves opens and you have 8 runners all the way to redline. The runners have a diaphragm that controls the opening and closing. The diaphragm has a vacuum line running to it and at 4800 where there is enough vacuum pressure, the diaphragm opens the runners. Ever notice how your Si at around 4800 drastically changes sound and it sounds like the car is going to explode? Well that changeover in sound is the manifold opening up.

http://www.92lude.com/images/flapper.jpg


This is what the middle section of the manifold looks like with the flapper valves. The silver diaphragm on the left side is what controls them. Until 4800 they are closed, but after 4800 they open up as shown in the picture. All the small piping and fittings are for Nitrous so don't look at those. So what's the mod? Simple, if you want more power sooner, unplug the vacuum line that connects to the diaphragm. Now the flapper valves will always be open at all rpm's. Yes, you will lose a little bit of low end power, but you will gain power sooner(above 3700) as a result of them being open. 4800 is a good rpm, but it's possible to take advantage of the 8 runner design before 4800 and by unplugging the vacuum tube, that's what you're doing. Since racing always takes place above 3000 or so rpm, you won't have to worry about losing low end power. After all, why else would you want your car to be faster if you're not racing it?? ;)

http://www.92lude.com/images/flapper2.jpg
This is where the flapper valve is located on the engine. You can see it's between the brake master cylinder and the left side of the upper intake manifold(attached to the manifold actually). There is a line connected to the top of it, just unplug it so it hangs or cap it off. I have ---- retentive people asking me all the time if stuff will get into the vacuum tube if it isn't capped off. Let's be realistic, the opening is smaller than 1/8" wide, do you think that with the hood shut, something will bounce around in the engine bay and land inside the tube which is tucked under the manifold?? Hell no. Unless your car sinks to the bottom of a deep lake, you're not going to get any water or dirt in there. Besides, that tube BLOWS are out when the engine is running, how is something going to get sucked inside there if there's 40lbs of air pressure blowing out of it constantly?

EGR MOD

Exhaust gas re-circulation is what it stands for. Of course there's probably some other technical term for it but basically, it does what the name says. Exhaust gasses are sucked into the EGR(via hole in the bottom of the EGR which is connected to the engine) and re circulated back into the intake manifold. I don't know about you, but wouldn't hot exhaust gasses be BAD for the air intake, which is supposed to be as cold and oxygen filled as possible? The engine's byproduct is carbon monoxide(or dioxide?)... would feeding an engine it's own byproduct be good for it?? Do you eat your own byproduct??? I sure hope not! So what do you do? Remove the EGR and cover the hole so exhaust gasses aren't sent back into the engine.

http://www.92lude.com/images/egr.jpg




It's hard to see in the picture, but look inside the circle between the two Nitrous lines and there is a black valve sitting there with a yellow line hooked up to it. It's easier to see on an engine that's not all cluttered with NOS plumbing everywhere. Basically the EGR has a plug, a vacuum tube, and two bolts holding it down. Unbolt the EGR and unplug everything attached. 1. Cap off the vacuum tube. Either get some tubing caps at a parts store or plug it with a golf tee. 2. Leave the plug alone. Zip tie it out of the way. 3. You can see that you have a hole left over where the EGR went. Get a thin sheet of metal and some tin snips. Set the metal on a table and put the EGR on top of it. Trace the bottom of the EGR on the metal and cut the shape out with the tin snips. This is your cover for the hole where the EGR went. Drill two holes that correspond with the holes in the EGR. Now, get the EGR bolts and bolt the plate down over the hole where the EGR went. Now you won't have exhaust gasses being shot out of your engine nor back into the engine via EGR. Your car might trip a check code but that's life. The check engine light is designed to detect errors in the emissions equipment and since you're removing some of the emissions equipment, it might trip a code.

Fuel Pressure Mod

After installing an intake, header and exhaust the car will have a ton more airflow which is good, but it can be bad if you don't have some extra fuel to balance it out. Many people like to install adjustable fuel pressure regulators but they're a pain in the ass because they have to be tuned constantly and the correct way to do it is on a dyno. Not many of us have a dyno handy all the time and even when there is one in town, it costs a lot to use. The stock fuel regulator gets its pressure by vacuum pressure, which is usually constant. If you want more fuel pressure, unplug the line connecting the fuel regulator with the intake manifold. Now the regulator can suck in as much air as it wants as it's no longer limited to the vacuum tube pressure. So find the line that goes from the regulator to the manifold and remove it. Cap off the opening from the manifold where the vacuum line went. However, DO NOT cap off the regulator! If you cap off the regulator it defeats the whole purpose cuz you will be stopping all airflow to the regulator. I saw someone put a K&N breather on the regulator. this is pointless. Nothing is going to fly into the 1/16" hole. Your idle may change a little due to the change in vacuum pressure, but that's something you'll have to get used to. Several people have done this and been very pleased, and I have had some excellent results as well on many cars.

Stock 95 Civic DX(Automatic)
With air box removed - 17.4@80mph
With air box removed and fpr mod - 17.0@80.5mph

Stock 95 Del Sol Si(SOHC VTEC, 125hp)
Air box removed, timing advanced, adjusted tire pressure - 16.0@87mph
Air box removed, timing advanced, tire pressure, fpr mod - 15.8@88mph

92 Prelude Si(my car)
All mods listed including SX adjustable regulator - 14.6@94mph
All mods with fpr mod(SX disconnected) - 14.5@94.6mph

Yes, I got a better time with the fpr mod over the adjustable SX regulator

http://www.92lude.com/images/fpr.jpg

This is where the regulator vacuum line connects to the intake manifold. On a stock car it's not a yellow line, but look in this area for a line connected to a gold diaphragm. Don't mistake with the flapper valve diaphragm, the fuel pressure regulator is the smaller gold diaphragm located on the fuel rail.

Re:info on ludes with how to mods
 

Don't listen to that, it's retarded.

Re:info on ludes with how to mods
 

I didn't even bother to read it. :P

Re:info on ludes with how to mods
 

the only thing i would bother doing would be the EGR mod,

the guy is a moron and doesn't understand what the
"flapper things" are for, or the FPR. or how engine vacume works, black delsol, tell that stupid ---- to come here so we can give him ----.

Re:info on ludes with how to mods
 

hey im being serious and give back to the community i have taken so much from

Re:info on ludes with how to mods
 

like the jyard sign says: useless ---- goes around back.

Re:info on ludes with how to mods
 

lol, black_del_sol.. doesnt look like you're getting anywhere, bud.

Re:info on ludes with how to mods
 

i have 8 intake runners on my celica. its the t-vis toyota variable intake system. it keeps the presure levels of the air going to the engine consistant. its pretty lame it dosent do ----. allot of people remove it. the prelude system should be pretty close to what that is. seems that most toyota engines have allot in common with honda engines.i wouldent even ---- with the system it dosent do much.

Re:info on ludes with how to mods
 

This is about the only part of the thread I actually read. I hear H-T has a great prelude section, and clubsi should fulfill all your bullshit needs.

Re:info on ludes with how to mods
 

the valves close of one of the 2 runners leading to the inktake port, increasing air velocity, resulting in better fuel atomization which is key for better emissions, fuel economy and power. it does plenty, basicly accomplishes what VTEC does but on a lesser level. unless i see dyno sheets proving it doesn't do ----, i'd leave it, unhooking it is a stupid idea, if your gona mess with it, remove it entirely.

Re:info on ludes with how to mods
 

are you still complaining about the horsepower #'s between the h22 and h23?

Re:info on ludes with how to mods
 

Having done my own experimentation, messing with the dual intake manifold (aka PRETEC, not VTEC, PRETEC) youll lose a considerable amount of down low power and your gas milage will suffer accordingly. You might gain some power in a 250-500 rpm drop in the activation of the pretec point but its better to leave it stock then to leave it open all the time. BTW youre pics dont work. The FPR mod generally makes a small difference in low-midrange power.

Re:info on ludes with how to mods
 

its a butterfly damn it. its there for bottom and midrange power and opens up for the upper rpm range. i dont know what you mean be FPR. im assuming fuel pressuse regulator. the sx regulator is also a fuel pressure regulator. so what the ---- are u talking about man. clear this ---- up. i dont know what the ---- your talking about.

Re:info on ludes with how to mods
 

it's in simple english man, go back to school.

Re:info on ludes with how to mods
 

I'll take up for you on this one Spenser. What the hell are you guys talking about. These are all pretty good tips for cheap horsepower (although maybe just a little), but are still useful easy to understand instructions. For those who dont understand maybe we can buy Spenser a plane ticket to the US and get him to do them for you.

Re:info on ludes with how to mods
 

Yea, before, you were cruising around town at 0psi, but after I/H/E, it's now 12psi! What a bunch of bullshit...typical ricer mentality. I sure hope the ECU can compensate for a small CFM gain.

-Tim

Re:info on ludes with how to mods
 

At part throttle it will be able to run fine, since it runs in "open" loop mode, relying on information from the O2 sensor and other sensors (Air temp sensor?) to control A/F ratio. but at full throttle the engine is running of pre programmed maps(hence the name PGMFI) so injector pulse and timing is set. So since the stock maps are tuned for Airflow of the stock setup, The Ecu has no way to compensate at full throttle. But the engine is not tuned for "max power" and probly runs alittle rich from the factory, so with the more air the leaning out of the mixture mightbe benificial? I dunno.

Unhooking the fuel pressure regulator probly reduces the fuel pressure even more resulting in less fuel.

I'm pretty sure that running a bit leaner from factory will result in alittle more HP, I'm not sure, Maybe the FPR mod does the reversal and adds fuel for the mods, I'm a moron.

I know my friend at the track runs slower times when he raises his fuel pressure on his D16.

Anyway, all of those mods are retarded, and he doesn't really explain how to do them in full detail, and since it sounds like it's written by a ricer, it's probly meant for more noobs, basicly it's a bad write up.

Re:info on ludes with how to mods
 

Re:info on ludes with how to mods
 

Actually, at part throttle, the car is in CLOSED loop. Only until you go WOT is it open loop.

Even with these mods that supposedly allow a ton more air in, the ECU will know about it via the MAP sensor. It's not just blindly injecting fuel at WOT; it still relies on a few sensors.

And finally, if you disconnect the FPR's vac hose, you'll be running rich. Think about it. At WOT, there's little to no vacuum to pull on the diaphragm of the FPR, so you get max fuel pressure. Only because it maintains a pressure differential between the injectors and intake manifold.

So yea, if I see a Prelude with a bunch of vac hoses disconnected, I'll just point and laugh...

-Tim

Re:info on ludes with how to mods
 

little stuff like this, weight reduction, and an auto-5 speed swap brought me from 17.3 to 16.2 on a very mildy modified accord