How To Increase Horsepower And Torque On Your Stock Engine

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    If you are like most people there are times when you wish your vehicle had a little more strength but upgrading your engine can seem pretty complex. In this How To we will look at the basic ways to increase your engine’s power and talk about the cost and how complex it can get for the average weekend mechanic.

    The first thing you need to do is understand that there are only so many things that you can do to your engine without voiding its warranty or causing it to fail emissions testing. In many states if you really want to modify an engine you have to do it on a vehicle built before the 1970s because any vehicle with an advanced emissions system must still comply with the stock standards. If you are modifying your vehicle for racing then all of that can be forgot because you won’t be taking it on the street.

    Is Modifying Your Engine Worth The Cost?

    This is a big consideration and although yes you can do things to any engine to improve its performance I often run into people that love to modify honda vehicles and put vtec engines from acuras in them. In addition they will add a turbo and an intercooler and completely re-engineer the vehicle from bumper to bumper. In the end they gain a couple hundred horse power and the suspension and other systems see improvement but what cost and what return is really found in such work? This for most enthusiasts is something of love. They want to have a CRX or Hatchback that can run well in the quarter mile because these vehicles were made to be gas misers and not for racing. The same is true for Volkswagen owners and even people driving base model camaros and mustangs.

    The honest truth is you will end up building a vehicle that can’t always beat its other class members and it will cost you much more in the end. In the first example someone replacing a Honda engine with an Acura engine you might think that if you can do this with a junk engine and do some mild modifications you are going to build something fast and cheap. But the reality is all of the other parts required will push your vehicle well beyond the cost of just owning an Acura with that engine and modifying the Acura to run faster.

    Trucks are another situation where people want to increase torque and horsepower for hauling and in some instances an engine swap might be justified but what about the other parts of the drive train that are not up to the use of a larger engine. I would never consider converting a 2wd to a 4wd even if I had all of the doner parts. The only way you might consider this if you were just swapping sheet metal but in reality that also has its problems.

    The main idea is you shouldn’t get into an upgrade so far that you are trying to make your vehicle something it isn’t unless that modification is so dramatic that the time and cost is worth it in the end.. in other words you need to get a grip before you start dumping all your cash into a dream that can’t come true.

    With that said lets look at some of the base modifications that you can make to increase the horsepower and torque of your engine.

    Intake And Aspiration

    One of the easiest and most effective ways of increasing horsepower and torque is to increase the air available and in doing so be able to increase the gas flow at the same time. A normally aspirated engine is one without a turbo or supercharger. If you have the option and many after market companies and even stock parts are available to add increased boost to your air intake. This will require additional tuning and parts but it is a start to increase your engine’s strength. Often aftermarket superchargers are available that won’t even void your engine’s warranty. Look into that first when choosing this modification. As for normally aspirated engines you can modify the air intake system to increase flow but for the most part you won’t be gaining very much. Aftermarket parts that feed air to your engine normally only produce a few horsepower and the cost is not justified. In addition if your flow is good from the factory you are also using parts that are for street use meaning if you are driving in the rain they are tested to work well in all conditions. Race parts do not take general driving into consideration at all so you can end up with flooded air filters and much more dirt which in the end costs you even more money.

    Camshafts For Higher Performance

    Many enthusiasts will want to modify their camshaft for more flow to the cylinders but doing so on new engines must be accompanied with other changes such as tuning your ECU to let it know the new camshaft is in place and to make the best use of it. This can be a somewhat complex and expensive change but after considering an addon turbo or supercharger this is probably one of the better options to improve your horsepower and torque. Remember if you are getting aggressive with your choices other engine parts will also need modification. When changing your cam you do need to account for all of your clearances so you only want to buy matched set parts so you know you are getting the full benefit. This includes lifters, push rods, springs and knowing all of the parts will work together and not cause piston interference or other mismatches.

     

    Exhaust System Upgrades For Horsepower And Torque

    One of the first changes many people do on their vehicles is a Cat Back Exhaust System Upgrade but in all honesty it is not something that will provide a large amount of improvement without other changes to your engine. If you were to take a small block Ford or Chevy V8 and upgrade its exhaust system without doing other changes to the engine you are simply making it louder. Loud is really not a goal when you are performing an Exhaust System Upgrade because it just brings attention to your vehicle.

    At the most with a high performance muffler and header system you can expect about a 10% increase in performance. Headers that are now on all factory vehicles vs cast iron manifolds on pre 1970 vehicles where where many improvements use to be seen. A header system can improve flow and will have small effects on torque.

    Once engine modifications are performed is when you see the most advantage of a high performance exhaust. This is because the Exhaust System becomes the restriction.Prior to those modifications you see much smaller gains.

     

    Final Note

    Tuning your engine and increasing its performance should be done with knowledge about how these systems work together and where the best performance gains can be found.

    Aftermarket parts can produce huge gains in performance and still keep you within your manufacturer’s warranty if you choose your parts wisely. If you are simply throwing parts at your engine to see if you can find gains there may be performance increases but you might end up causing more problems than you can think of.

    You should always start with an engine that is easily modifiable. Sure you can take a yugo engine and throw some Nitrousoxide on it and burn it out in a couple runs or you can find an aftermarket supercharger with an ECU programmable chip upgrade and leave everything else basically the same and have a 500hp engine that you can run day in and out without worry.

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