# Quickest/cheapest mod for more low rev torque?



## JamesR (Oct 19, 2004)

Hi

I have a stock standard 1992 Sentra 200STi (dunno what it would be called overseas, but it's the SR20DE powered sedan) which I am quite happy with. However, I could do with a little (or a lot!) more torque at 2000-4000rpm and was wondering what the cheapest/quickest way to achieve this would be, on a bang-for-buck basis. I'm not after more peak power really, but if that's a happy side-effect I wouldn't mind


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## Matt93SE (Sep 17, 2003)

nitrous.


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## Chuck (Nov 19, 2003)

Matt93SE said:


> nitrous.


turbo


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## lshadoff (Nov 26, 2002)

JamesR said:


> Hi
> 
> I have a stock standard 1992 Sentra 200STi (dunno what it would be called overseas, but it's the SR20DE powered sedan) which I am quite happy with. However, I could do with a little (or a lot!) more torque at 2000-4000rpm and was wondering what the cheapest/quickest way to achieve this would be, on a bang-for-buck basis. I'm not after more peak power really, but if that's a happy side-effect I wouldn't mind


Light pulleys, flywheel, and wheels yield more power to the wheels across the board by decreasing rotational mass.

Lew


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## Coheed (Oct 12, 2004)

lshadoff said:


> Light pulleys, flywheel, and wheels yield more power to the wheels across the board by decreasing rotational mass.
> 
> Lew


May not be the cheapest way, but will make any car A LOT more fun to drive. Nitrous is the cheapest way to get tons of low end torque.


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## nova73guy (Mar 30, 2004)

Coheed said:


> May not be the cheapest way, but will make any car A LOT more fun to drive. Nitrous is the cheapest way to get tons of low end torque.


Just make sure you research this stuff, and start small. A guy at the drag strip last year had a sr20de he built, and then put a huge shot of nitrous (not sure exactly how much) on it. Blew the engine. Very dangerous if you don't know what you're doing.


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## asleepz (Feb 24, 2004)

Underdrive pulley, CAI, Exhaust


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## Nismo1997 (Dec 26, 2003)

Header, exhaust, cai,advanced timing, better clutch, pulleys is a way to start


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## jmann98 (Aug 20, 2004)

I've read that cam gears will let you adjust your power/torque across the rpm band. But if you increase your power low, you'll loose it up high. But if do 99% of your driving below 6000 rpm, look into it. Does anyone else know the scoop on these? Stillen has some for $250, but they're probably cheaper elsewhere, like JWT. You never hear about them b/c most folks here want mainly to increase their high rpm power.

You're next best bet is to lighten or buy a light-weight flywheel. Although this won't technically gain you power that you can measure, you will accelerate faster, and it will feel faster.

Pullies and the JWT ECU ("chip") have shown improvements below 4000 rpm. Pullies can make 6-7 hp up top, too, on the SR20DE. The crank pulley is much cheaper than the chip.

I haven't seen a dyno on it, but I think advanced timing (switch to high-octane gas) helps in the middle and up top. We Americans with the cheap gas think of this as a free mod. But if you do it for enough years, one could buy a header or chip instead for the same money. I'd guess where you are at it might be $5 more a tank. Here its almost $3 extra a tank.

Changes to the exhaust system are not what you're looking for. They are mainly for high end breathing. 

Lighter wheels won't really help until you're in second gear, probably third. You'd have to spend $400-$600 just to shave a few pounds off your wheels. Even considering rotational energy, probably not your best bang-for-your-buck mod. 

If you get the cam gears, please do a write-up. I've only read one thing ever about them.


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## jmann98 (Aug 20, 2004)

Oh yea, a cold air intake helps a bit down low, and definitely in the middle and top.


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## Exalta (Jan 21, 2003)

weight reduction  

get rid of your heavy sub boxes, whatever tools, stuff you put in the car that you dont need, matting, carpets, noise reduction tar


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## shift_of_legend (Jun 2, 2004)

If you want nitrous to provide good low end torque, you need to get one that is computer controlled. If the kit just sprays nitrous, it's not safe to engage it early in the RPM's. Nitrous if sprayed at a constant rate is introducing more oxygen into your cylinders than they can handle at low revs. At higher revs say 4000 or 5000 and above is fine. Picture this, 100 cc of nitrous (ball park figure) being shot into your engine. At 1000 RPM it is getting 100cc's (ball park math), at 2000 RPM it is spreading that 100cc's across, so it's 100cc for the 2000RPMS meaning for every 1000 RPM the cylinders are being filled with 50cc's and so on and so on. This is why nitrous is safer at high revs.

For nitrous to be safer at low revs, you need a kit that gradually increases the spray pattern as RPM's increase. If you don't have such a control, you will blow your engine if you engage nitrous too early, because of the super lean condition. Even if you dump fuel at the low revs, you'll still have to retard the timing waaaaay back and get low compression pistons to manage that....and who knows, you might not have much traction and lose anyway.


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## lshadoff (Nov 26, 2002)

shift_of_legend said:


> If you want nitrous to provide good low end torque, you need to get one that is computer controlled. If the kit just sprays nitrous, it's not safe to engage it early in the RPM's. Nitrous if sprayed at a constant rate is introducing more oxygen into your cylinders than they can handle at low revs. At higher revs say 4000 or 5000 and above is fine. Picture this, 100 cc of nitrous (ball park figure) being shot into your engine. At 1000 RPM it is getting 100cc's (ball park math), at 2000 RPM it is spreading that 100cc's across, so it's 100cc for the 2000RPMS meaning for every 1000 RPM the cylinders are being filled with 50cc's and so on and so on. This is why nitrous is safer at high revs.
> 
> For nitrous to be safer at low revs, you need a kit that gradually increases the spray pattern as RPM's increase. If you don't have such a control, you will blow your engine if you engage nitrous too early, because of the super lean condition. Even if you dump fuel at the low revs, you'll still have to retard the timing waaaaay back and get low compression pistons to manage that....and who knows, you might not have much traction and lose anyway.


I beg to differ. An engine will detonate when the Indicated Mean Effective Pressure (IMEP) in the cylinder is above a certain value. The IMEP detonation limit is dependent on the engine design and is constant across the rpm range. So any WET nitrous setup that is safe at high rpm is also safe at low rpm. The amount of fuel required to use up the nitrous is always there, so there is no leaning out to cause detonation.

I have the JWT dry nitrous setup (ECU turns the injectors on full when spraying) on my turbo car. It only functions when launching and automatically stops spraying when the MAF maxes out due to the combination of nitrous and boost. It is used to spool the turbo up fast, and dropped my 60' times by 0.3 seconds.

Lew


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## Coheed (Oct 12, 2004)

Exalta said:


> weight reduction
> 
> get rid of your heavy sub boxes, whatever tools, stuff you put in the car that you dont need, matting, carpets, noise reduction tar


I agree, making the car lighter is free mostly. It makes your car faster, but it doesn't make torque


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## jmann98 (Aug 20, 2004)

Weight off the wheels and tires helps a lot more than weight removed elsewhere. I think an underrated weight loss area is the tires. For example, the Falken Azenis Sport 205/50/15 is 22.6 pounds, while the Toyo T1-S 205/50/15 is 18.5, more than 4 pounds less in the same size. I'm no physicist, but I'm guessing pound for pound, tire weight is more important than wheel weight because its farther from the center of the circle that is your wheel/tire, causing the rotational energy to be greater, and therefor weight to be greater on a pound of spinning tire than a pound of spinning wheel. 

I'm personally looking at trading out my stock '97 se-r wheels w/Azenis to 11 pound 15X7 wheels with Toyo T1-Ss, because I would be taking 9 pounds off each wheel. Its been said that each pound off the wheels/tires, is the same as 10 pounds at speed (although I don't know at what speed, probably not until 60mph), which would translate into taking 4X9X10 pounds off my car, or 360 pounds. That'll help move your car, and save you gas mileage, and decrease unsprung weight by 36 pounds, which is good for handling and braking as well, particlular at speed.


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## JamesR (Oct 19, 2004)

thanks for the ideas so far... even the more outlandish ones! def not gonna take out my sound, im trying to make de car more streetable! as for nos.... not for a LOOOOOOOOOOOOOOOOOOOONG while yet  even turboing her's gonna cost a bucketload (i bought her for R30000, turbo wil cost close to R10000 with all the neccessary mods). gonna advance my timing and do cai first cos dats de cheapest by far. ive got shitty 14"s on her at de mo but they've stil got some decent tread. gonna move up to 205/55/15's when the time comes. haven't thought about pulleys, will check out the cost first. ta


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## nnoriega (Dec 18, 2003)

91 oct fuel, advance the timming degree, remove the extra tire in the trunk and you`ll see, that it`s cheap.


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## JamesR (Oct 19, 2004)

nnoriega said:


> 91 oct fuel, advance the timming degree, remove the extra tire in the trunk and you`ll see, that it`s cheap.


Down here in sunny Cape Town we run 97 octane my friend  my cousin's got a bitch of an STi that's running 19 degrees of advance no problem! Gonna also maybe skim the flywheel, seems cheap compared to the other options


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## niky (Jul 20, 2002)

Just don't skim it too much... don't take off more than a few pounds, and balance it after... some guys on "skimmed" stock flywheels over here (and no, amehrikanistch naysayers, they don't fly apart... at least, not yet.) report the best durability if you only take off 15% (don't forget to have it balanced!!!)... but it's hell to drive in traffic if you're not used to it.


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## Zen31ZR (Mar 24, 2004)

Actually the flywheels rotational mass helps low end torque. Lightening the flywheel will cause the engine to lose some drivability, you'll stall out coming off a stoplight a lot easier. Lightening the flywheel helps the engine rev quicker but it also drops rpms quicker. 
If you want more low end torque, simply advance your cam(s) 2-6 degrees. Don't try the timing advance BS, unless you have very high octane fuel, timing should already be optimally set from the factory. 
Low end torque is a function of intake air velocity. Large bore intakes such as CAI/Short Ram etc can actually cause a loss of low end torque in favor of top end flow. If you want more low end, find a way to restrict the intake. Sounds ridiculous, but if you can increase velocity , low end torque will increase. Its the same concept of having a 2 bbl carburator on a 400 cubic inch engine, which I had in my 71 Ford LTD. The low end torque of that monster could actually yank the front wheels up off the ground, but it ran out of breath at around 4000 rpm due to the small bore carb. Things to think about.


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## pete? (Jul 6, 2004)

balliztik in relation to what u just said would this help? or would you have to decrease the diameter of the intake pipe? exhaust restrictor


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## Zen31ZR (Mar 24, 2004)

1.6pete said:


> balliztik in relation to what u just said would this help? or would you have to decrease the diameter of the intake pipe? exhaust restrictor


 Velocity is a function of overall intake diameter, not simply restricting flow into the engine at one point. If that were the case, max torque could be achieved while the engine was at base idle with the throttle completely closed. No, the best way to make low end torque by the method I talked about is to make an intake pipe consistent in size, but a touch smaller than stock, from filter to throttle body. For absolute low end performance, smaller bore intake runners should be used too though, as well as a smaller bore throttle body. Short of designing your own intake manifold, that won't happen. 
What you want to avoid with this is any major transistions in bore size, from smaller to larger, because you will lose all the velocity you gained in the early part of the system if say the intake manifold runner bores are too much bigger than the pre-throttle body intake piping. 
Mostly the accepted way to make more low end torque is to move (advance)the cams, thus changing the airflow characteristics.


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## Greg200SE-R (Feb 5, 2003)

JamesR said:


> thanks for the ideas so far... even the more outlandish ones! def not gonna take out my sound, im trying to make de car more streetable! as for nos.... not for a LOOOOOOOOOOOOOOOOOOOONG while yet  even turboing her's gonna cost a bucketload (i bought her for R30000, turbo wil cost close to R10000 with all the neccessary mods). gonna advance my timing and do cai first cos dats de cheapest by far. ive got shitty 14"s on her at de mo but they've stil got some decent tread. gonna move up to 205/55/15's when the time comes. haven't thought about pulleys, will check out the cost first. ta


Geez guys, James' car sounds like its used strictly for daily driving and he wants better stop and go/onramp performance. No offense to James, but we should be suggesting things as if he were an old man whose only concern is drivability. 

James, if you want good torque and don't care about top-end, then simply stick with STOCK. The factory designed your car just for what you have in mind. 

You did get some good replies though - look into the more "passive" mods that reduce load on the engine rather than boost its peak HP. Pullies are perfect for you, but a flywheel isn't worth the drivablilty sacrifice. Bump your timing up a bit if you have decent gas where you live. Look into the ground wire kits as well to give your ECU+sensors a cleaner reading on what your car is doing. These mods generally boost wide areas of your torque curve and don't trade low-end for high-end as much as the more common mods. If a JWT ECU is available for your car, that will also boost overall driving characteristics and give you back some gas mileage as well. As far as wheels, going with a wheel-tire combo that is smaller in diameter will effectively give you shorter gearing.

By the way, a CAI WILL lose low end. I have the AEM and even though it is resonance-tuned to give back some low-end, the overall torque loss was noticeable. Nissan did extensive testing on the stock box and should be good for you. Keep in mind that if you decide later on to tune for performance, you will already have some great mods here to build upon. good luck.


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## JamesR (Oct 19, 2004)

Greg200SE-R said:


> No offense to James, but we should be suggesting things as if he were an old man whose only concern is drivability.


LoL... Dunno whether2b insulted or not  I'm only 23! I tend to drive like a demon on the highway, but let's be honest, what fraction of the time do our cars actually spend there? Most of the time its residential and/or traffic driving, and for that you REALLY need some "pull". I don't want2have2gear down every time a V-Tec comes flying past me on the highway either  My only gripe is why modding a car should cost so much damn money! I would seriously consider turboing if it weren't going to cost a substantial fraction of the car's value  Thanks for the input guys


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