which engine mod first?

[sk84food22]

i am considering getting a intake or a new exaust? i am just not quite sure which one would overall be better for more 'kick'. i know if i get the intake i will have more throttle response and better mpg's. btw i have a 99 xsport rwd 4.0 5speed. :exp:

 

[jrowe6]

ohv or sohc??


i swapped out my stock panel filter for a K&N and modified the air box a bit and got much better low end response and also got the added sound from the intake, which i like.

as for the exhaust, i replaced my muffler with a hi flow muffler, didnt do much performance wise. in my opinion the headers should be the first thing to go on the exhaust on these things. the new muffler definitly sounds better.

 

[rhauf]

many after market "cold air" intakes just suck air from under the hood (Exposed filter).. this = warm air intake and will actually produce less power than the stock intake system (which by the way, is a cold air intake system)

upgrading the filter element may give some advantage, but personally I'm not a fan of wasting money on shiny chrome intake systems which hurt horsepower.

upgrading exhaust usually just changes the sound of the vehicle, unless you have a ton of other mods (allowing the engine to breathe more than the stock exhaust can allow for)

changing the intake wont change fuel economy either, in a fuel injected engine, the mixture is always correct even with a clogged filter (the closed loop injection system adjusts and compensates for altitude, air pressure, etc.. thats what MAF and O2 sensors are for)

 

[aldive]

The best bang for the buck is underdrive pulleys.

 

[aldive]

upgrading exhaust usually just changes the sound of the vehicle, unless you have a ton of other mods (allowing the engine to breathe more than the stock exhaust can allow for)

Not true.

changing the intake wont change fuel economy either,

It can if you don't drive toohard.

 

[rhauf]

Well since you've contradicted what i said with nothing to back it up, here's a scientific answer to you're suggestion of underdrive pullies.. i know everybody has their preferences, and thats fine.. i'm just pointing out to the OP that there are a lot of "performance" parts on the market which are designed to do nothing except empty you're wallet.. intake systems is one of them, and huge exhaust to cruse a stock engine at modest power levels (normal driving) is a waste of cash, too. consider the CFM of an exhaust system at the point it becomes restrictive, and the CFM a stock engine can output.

The best bang for the buck is underdrive pulleys.

underdrive pulleys.. with the exception of the water pump turning slow (and cooling the engine less in the process) i'm dying to hear how they free up horsepower.

lets see, we have the alternator, power steering pump and a/c left.. right?

lets take the alternator first, if it turns slower, the regulator will increase the voltage to the armature in order to maintain the needed output (13.8v), this increase will add drag to the pulley.. at the rate of (not counting frictional and resistive losses) 1 horsepower per 746 watts of electricity generated. so turning it slower will still take the same drag from the crank. to put it another way, if the alternator is outputting 54 amps (746 watts at 13.8 volts), it's going to take 1 horsepower to run the alternator, no matter how fast it's going.

second how about the power steering pump? there may be a very slight gain here (due to frictional losses in the pump), but when hydraulic pressure is not being used (wheels are not being turned) there is very very little drag here anyway. and if hydraulic pressure is being used, the pump (like the alternator) will have to be turned that much harder to create the same PSI if it's going slower.

and the a/c... well, there would be a potential gain here, except you can turn the a/c off and then the compressor is spinning freely.. and for fuel economy (with a/c on), if the a/c compressor spins slower, it's duty cycle increases, to maintain the same pressure in the line. so no gain here either.

personally, i see no reason to trade in idle performance of the alternator, power steering pump, a/c and engine cooling in order for some imaginary horsepower gains. the *only* feasible gain i can see from the system is the (slight) reduction in rotating mass acceleration when the engine rpm increases.

 

[jrowe6]

i agree with rhauf. lowering the rpms of the alt pully will make the alt need to be turned harder meaning more torque from the belt. it would be better to spin the alt faster with less torque than slower but harder. better belt life and better alt life.

 

[jrowe6]

your best performance gains will come from reducing friction and increasing air flow. good engine oil, good ATF, good gear oils, repack the bearings if youre up to it. that will make the truck move easier and require less power to maintain speed which will leave alot more hp for acceleration.

idk if you have the sohc or the ohv, so if you have the sohc maybe this is not as true as with the ohv which is what i have. but the stock airbox is definitly the most restrictive part of the air intake. if you make the opening twice as big you will see some good improvement in throttle response and some extra pulling power in the higher rpms. dropping in a good filter like a K&N will make it flow just that much more. i would do that versus spending the money on some prefab cold air intake. you could spend that money replacing all your lubricants. once you have opened up the intake a bit them you might consider a catback exhaust or something to complement the extra air flow. i would not do the exhaust first. you will be dissapointed with how far your money got you. if you do it all at once that would add a good bit of "kick" tho.

i have the intake done with a K&N and an after market muffler. i would say maybe a 10hp gain from all that. i dont really remember how big a change it made, i did that a few years ago. right now i can say for sure that running 5w30 mobile 1 full synthetic made a huge difference. im doing my differentials and transfer case next. from what i hear that makes a big difference as well.

 

[2000StreetRod]

SOHC or OHV?

No matter which engine you have to improve acceleration make sure that the throttle plate opens all the way when the accelerator is "floored". Search on "throttle cable mod" for more information.

For better fuel economy, acceleration and longevity switch to full synthetic lubrication. Start with the engine and then the differentials. If you have an automatic transmission switching to synthetic ATF may not be worth the cost since Mercon V is semi-synthetic.

Switching to a thermostatically controlled electric motor driven radiator fan will increase fuel economy (faster engine warmup in cold weather and less drag year round) and engine responsiveness and acceleration.

Utilizing an underdrive harmonic balancer in conjunction with an electric cooling fan usually avoids overheating problems. It may be necessary to switch to a larger output alternator or overdrive pulley depending on your electrical demand.

The airflow capacity of the SOHC heads is much greater than the OHV heads so the SOHC will benefit more from improved intake and exhaust flow. Removing the silencer cone from the air filter box costs nothing, retains cold air intake and removes airflow restriction. I believe that a high flow drop in air filter replacement is superior overall to a cone filter that pulls intake air from the engine compartment. It's also less expensive. I plan to revert to that configuration even with my custom 4 inch diameter intake system.

I believe the stock intake system is more restrictive than the stock exhaust system. My SOHC really seemed to come alive and became much more fun to drive after I made my intake improvements. There is no doubt in my mind, however, that switching to a higher flow capacity muffler will further increase my fuel economy, max performance and driving pleasure.

 

[SA-Xplorer]

" but the stock airbox is definitly the most restrictive part of the air intake. if you make the opening twice as big you will see some good improvement in throttle response and some extra pulling power in the higher rpms. dropping in a good filter like a K&N will make it flow just that much more."

I have a 96 OHV I just bought. My first American car. Nice! I want to mod it a bit. How did you modify the filter housing and did you just enlarge the hole on the side of the wheel arch?

".. an after market muffler."

what about removing the CAT? I am in South Africa and its not mandatory to have one. What implications does this have for the various sensors making the engine run properly?

".. right now i can say for sure that running 5w30 mobile 1 full synthetic made a huge difference. im doing my differentials and transfer case next. from what i hear that makes a big difference as well.

Can you please give a list of what lubricants i can put where to improve things?

As I dont really know the history of my x, it would be wise to change what I can as soon as...serpentine belt, shocks, lubricants, filters... anything else?

 

[celly]

Since the OP was asking an exhaust or intake question, I say...it doesn't matter. Both mods go hand in hand, IMHO. I personally noticed the biggest bump with exhaust, but the intake was done within days. They work well together because the two mods are complementary, i.e. you open up the air the truck inhales and the air it exhales. Tie them together with custom tuning and you'll be pleased.

 

[Sams01XplrSprt]

i got single in and dual out 40 series flowmasters on my sport and i love how it sounds.

 

[jrowe6]

sa xplorer......


lubs: engine oil, trans fluid, transfercase if you have one, differential(s)
you can also repack the wheel bearings which should help a bit.

air box: if you look at the air box it has a small funnel in the front going right behind the head light. i pulled that out. thats all i did to it. im planning on modifying it further so it sucks in only cold air and possibly fabricating some type or "ram air" intake

 

[SA-Xplorer]

jrowe6... thanks for the response. I got happy over the weekend. I bought a Simota fan and put that in with a Simota cone filter, which I fitted into the filter silencer. I did however measure and hack off the funnel at the end of the silencer and make the hole bigger. sadly, the simota filter is a bit big and the air flow only goes thru the centre of the filter, not the outsides. I am going to custom form a fibreglass shroud to house the filter. This will have a wide flange (about 8") that bolts to the side where the air hole is.

This weekend I will mod my throttle body to improve airflow. I also want to put a smooth bend tube inside the stock Ram air tube to smoothen out the airflow around the corner and into the TB.

I also want to upgrade lubs. Royal purple is expensive, but seems to add its little bit to the mpg improvements. Any comments?

 

[SA-Xplorer]

Another thing.... is there an electric fan spec available for the 4.0L OHV to treplace the pulley radiator fan? I would love to free up the wasted HP there.

 

[jrowe6]

i dont know if there is a specific e-fan kit for that exact truck and engine. i think most people just buy an e-fan kit and custom install it. i believe all it takes is mounting the fan and sticking a little tempature thing into the radiator, inbetween the fins. the fan is set to turn on and off when that little temp thing tells it its between a certain temp range. so really you just install the fan itself, wire it to the battery and let it do its thing. those kits are probly like $50

 

[sk84food22]

thanks for all of the help and info people i think i am going with the k&n filter first and go from there also my engine is the ovh. no idea what the difference is really between the ovh and sohv. also i am wanting to put on some bigger tires will 31s fit with no lift? also i was looking at retread tires would they be worth my money or should i just go and buy new ones?

 

[jrowe6]

sk84food, there is a tread dedicated to tire size versus lift and model year. search tire size.

31's will fit. then you can do a torsion twist and shackles, which will cost like $50 total and that will get you 2" of suspension lift.