Simple power mods?

I have a 97 Dodge Dakota ,I installed dual exhaust and was wanting to know if anyone knew of some simple power mods that can be done to give my weak 3.9 , a little more 'power ? I saw a spacer that goes between
the air intake and the intake manifold in Summit catalog that "claims" a power increase, has anyone in here ever installed one of those and recieved the "claimed" power increase ? Would a hotter ignition coil help maybe ? Thanks !
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That should be about the same thing as a high rise manifold that we used to use back in the 70's to increase power and fuel economy. Back then we were very surprised that when we added spacers under the carb, between the carb and the intake, it actually increase fuel economy and performance. If there is a way to open up the exhaust as well, such as headers, that will improve it more than anything else you could do. But I don't know how legal it is to add headers anymore since the introduction of the catalytic converter. I saw an article in pop hot rod in the mid 80's where they took Ford catalytic converters and put them on Chevy vehicles to increase performance, it seems that at least back then the Ford converters were more open and didn't choke down the exhaust as much as the other vehicle makers. They may all use the same converters now though, I don't know, I have not worked on an engine in 30 years.
KY

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to
While it should be, it actually isn't. You are talking about too very different animals here.

Yes they did and for many reasons. First, they kept the carb cooler which allowed for a denser fuel charge (performance), second, they helped in the mixing of the air and fuel prior to entering the cylinder (economy) and third, in some cases they increased the air flow velocity which helped to cram more air and fuel into the cylinders (performance). In a modern computer controlled multi-port fuel injected engine, the first two reasons are eliminated and all that is left is the last one and even there, unless the design was inefficient (much more common with the factory manifolds of the 70's), there is little chance of any ram effect either so the only real mileage improvement comes from the weight loss of your wallet.

improve
Once again, this is incorrect. Todays engines are specifically set up to run the way they were built. Opening up the exhaust even in the past helped the most at higher engine RPM's. Todays engines are configured to run with an expected amount of back pressure and the valve timing is set up with that in mind. IF you open up the exhaust, you will be spitting some of your air fuel charge into the exhaust and the O2 sensor will see that as a run rich condition and lean out the mixture. This will result in less power which will also reduce mileage and create a high ping rate as well.

I am unaware of any law against adding headers as long as they are compatable with the emmissions standards of the vehicle.

catalytic
seems
choke
in
With the push for better economy, I would say that for the most part, the factory converters for standard passenger vehicles are all just about the same for flow characteristics.
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here are a few things I found while looking for info on my dodge stealth RT. Seems to be applicapble to most vehicles.
Sounds feesable
http://www.ultimateresourceguides.com/content/freemods/88-91crx-freemods.html
KY

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There is really not much that you can do to that engine to increase its power. I'm not sure if there is a power programmer available for that engine but if there is, that is just about the only simple (but not cheap) method that I am aware of for that engine. As for those spacers, with today's computer controlled fuel injected engines, unless there is a flaw in the design of the intake manifold to begin with, they have little to no effect. Now if you want real power, you could always super or turbo charge it and there may be a supercharger kit available for that engine.
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Joe, I have built and driven many high performance vehicles in my life and the one thing I can say is that it is never simple nor inexpensive. Today, it is even more complex than 30 years ago. I can also state that the most effective mod is always cubic inches. High Tech is expensive and the return is less effective than more inches. It is also safe to say that any money invested in performance must be considered lost financially. You will never realize the investment in increased sales price when changing vehicles. So, my advice is to find a wrecked late model with a 5.9, buy it complete with gearbox, wiring harness and computer and swap out the 3.9. It will be worthwhile both in performance and economy, as well as affordable fun. Steve

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Joe Cool wrote:

The air spacer doesn't work. I've never seen a single dyno sheet that proves it. There's no fuel in that area, so all it does is change the air flow. In the old days - carb days - getting more power from a stock engine was pretty simple. The factory has a very conservative tune, so you just made it more "aggressive". Add timing, add fuel. That has to be done by reprogramming the computer. Check with Jet and Hypertech. Moving the air in and out better is usually worth something. The factory exhaust is pretty good. After market systems will improve power at the top end. But you don't get a lot of nag for the buck there. A cold air induction is actually worth some power. The factory intake is kinda restrictive. A drop in K&N air filter won't help at all, though. Another tried and true method is changing the rocker arms to a bigger ratio. Increasing the rocker arm ratio is like adding a slightly bigger cam. All magnum engines use the same design rocker arm. The 3.9, 5.2, and 5.9 use exactly the same parts. But the V-10 uses a longer ratio. Swap in the V-10 parts and gain some noticeable power. I have a set for my 5.9 sitting in the garage waiting for me to install them. Don't forget the non-engine improvements - lower gear ratio, lower weight, better aerodynamics, low drag tires.
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Funny how back in the 70's I had a 71 ford Torino GT(351 cleveland, factory holley 4 barrel with vacuum secondaries) and stock off the lot it got 28 miles to the gallon on the highway and in those days I rarely dropped below 90. My Dad told me I was lying until he and I drove it to Miami one week. He hasn't stopped talking about that car since. After the octane dropped below 100 it wasn't drivable so I sold it.
KY

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KY, What causes that is the NO restriction. All engines are heat engines and the more heat you can generate from a given fuel charge, the greater the air charge expansion and more power, but when temperatures exceed 3500 degrees F in the chamber, the nitrogen in the air charge will combine with the free oxygen molecules and create NO in the exhaust gases. By reducing that peak temperature below 3500, it drastically reduces the NO. Hence we have EGR and lower compression ratios. This introduces thermal inefficiency and we have poor economy. It's a trade off. Steve

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when they start using ethanol more will that raise the octane, slow the burn? So they could raise the compression ratio and get the economy up? Seems it would be better to get the economy up with supply going down.
KY

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KY, That's a loaded question. Yes, alcohol allows a higher compression ratio without detonation risk, but the 3500 degree NO problem is still there. Ethanol has 85% of the latent energy of gasoline, so your mileage will be 15% less on pure ethanol right up front. With methanol, you will lose 30% and natural gas 25%. Diesel, on the other hand has 25% more latent heat by volume and you with realize 25% increase in mileage. Interestingly, all these hydrocarbon fuels have the same energy by weight. There is no free lunch. As long as the NO emission rule is enforced, thermal efficiency will be compromized. Great strides have been made with diesels however. This has been realized by the multiple injection events per cylinder cycle. By doing this, peak pressure and temperature has been reduced, which reduced the typical diesel clatter (detonation), allows lighter weight crank and block assemblies and higher engine speeds.(broader power band). Of course this has had the effect of also reducing thermal efficiency somewhat from .39 lbs per HP hour (BSFC) to about .42 lbs per HP hour, but as long as we buy fuel by volume and not weight, diesel is the hot setup. Steve

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I have the 2" spacer in my 318 1995 4WD SLT and I also put in an MSD coil, dual exhaust, Mopar HP computer and K&N filter. The biggest gain was in fuel economy that went from 13mpg average to 17mpg. Highway milage is almost 18mpg, but not quite.......:-). Torque increased quite a bit too with it not shifting much on small-medium grades when towing. I just went over 172,000 miles and it still runs great with no oil usage. These modifications have been installed since it was at about 50,000 miles and the savings in fuel alone has paid for them several times.
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What did you spend for the mods you listed. was the K$N a drop in or did you get the whole thing?
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After the exhaust system which may vary a lot depending on where you live, I would estimate about $1,000-1,200 US. I got the K&N airbox and filter made for Dodge trucks.
Ed

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