unhappy with performance

[springtensi0n]

along with just about everyone here, ive spent quite a bit of money to make my explorer fast. its a 1995 4 door 4.0 ohv, mods include mac intake, pro-m maf, bbk tb, jba headers, cat back exhaust, and a apten chip, trottle cable mod. my problem is, i dont feel like i have as much power as i should. when i slam the pedal, even today when its been raining all day, i barely spin my tires (not that i want to in rain, but just as an example), unless im turnining. dont even ask me about dry days... it pretty embarassing. i raced my friends 99 sohc, and it totally destroyed me. is this typical? i know it has around 30 more horse than the ohv does, but i had nothing for him. and one more thing, i had my friend do my exhaust, he made the pipes 2 3/4, is this too big? i dont know a whole lot about exhaust, but if the pipes are too big, wouldnt that cause lack of power at low rpms?

 

[karl_burns]

It could

I have one 2.25" pipe. You'll lose back pressure with too big a pipe. The headers also make you lose low end torque, so just as you were probably getting into your power curve, your buddy tapped his brakes.
Run some Sea Foam through. A good $10 fix that woke up my engine. there are plenty of topics on it here.
Try that, and keep us posted. Also, remember this thing weighs so mu that small increases in horsepower won't feel nearly as noticeable as a ricer that weighs 1/2 as much.
Karl

 

[springtensi0n]

i tried some seafoam not long ago, and i didnt get nearly any white smoke. i aso didnt notice much of a difference. i used about 3/4 of it on my intake and i the rest went into gas. the "race" was on the highway at a 65mph roll. we tried it a few times, he went as soon as he heard my exhaust, so i got a bit of a head start and he still took me. thinking about it now, that was before my i replaced my ujoints (one with no bearings in it) and with my apten chip off because i was running regualr octane. today i have my chip on w/ 93 and it still feels *slow* for an explorer. (not being able to spin tire in rain) *shrug* i guess my subs could have some kinda impact on that. im going to try a few things, ill keep this up to date.

 

[dman726749]

what gears do you have in your diffs, it the are 3:55s and you are runnin 32" tires your acceleration is going to suffer a good deal.

 

[springtensi0n]

actually, i forgot to change that. i tossed the swampers, im going for the 'street' look again =/ i have the 3.73 Limited Slip (tow package)

 

[bates]

Maybe your cats are plugged.

 

[springtensi0n]

i just got my emissions tested two days ago (and passed, whoo hoo...). if they were plugged, wouldnt that make me fail?

 

[TheRookie]

You can pass emissions with a partialy plugged cat.
Karl, backpressure is the enemy of power. FLOW however is your friend. These two things are far too often confused. You see if the exhaust gasses are flowing fast they will naturaly create a vacuum effect called scavenging. This intern helps to draw out spent gasses. This is also what too large a pipe lessens. Backpressure is your enemy

 

[bates]

I thought lessening the backpressure will decrease low end torque? Like when you have a big hole in your muffler, the truck isn't as quick. Or is this the confusion you spoke of?

 

[Ak LTD Xplorer]

my X with 3:73LS would smoke them on dry pavment..that was with my old tire's tho..i don't know what it's gonna do now with the 31's

 

[springtensi0n]

yeah, thats what i thought. sure backpressure can hinder performance, but shouldnt no backpressure = no torque? which would explain me not being able to spin tires even in the rain. *shrug*

 

[Ak LTD Xplorer]

BTW my truck's stock

yes i think if you lose to much backpressure you lose low end..is this right?

 

[TheRookie]

Yeah thats the confusion I speak of.

 

[wired_af]

Can't even spin the tires a little in the rain? I can usually get a little chirp in the rain, with my stock X. Mabey its because I have a sport.

 

[blkexplorer]

Hey I just have a 95 XLT OHV with no mods at all and I was able to race a 99 Limited SOHC

It was not an easy win, but I was suprised to win as I have heard the SHOC are faster or have better response than the OHV

I've been thinking about making mods to my X, but after trying a SOHC 99 X and a few others, I am just not that willing to pay all of the money involved for an increase in HP that might not be as noticeable as i would like.

 

[OC_Explorer]

Cant even spin the tires in the rain??? When i still had my stock tires i could spin those things while turning like nothing. Even now with 31's in the rain i spin those puppies like crazy(and reverse on dry road). Its hard not to. And i only have a kkm and flowmaster.

 

[springtensi0n]

yeah, its pretty pathetic. i wish i knew (for sure) what was wrong with it...

 

[GooseR]

not disagreeing with the backpressure thing, but i read that you dont want any back pressure. when you go with a bigger piping you lose velocity, and when you lose velocity, (for example the exhaust turns around in the pipe, going back into the engine). a little is good for engine reliability but you dont want it for performance. now if you had stock piping with a less restrictive muffler, youd gain hp by losing restriction. now if you have straight pipes with stock size, itd be good because you would lose the backpressure(good) and still have the flow velocity not to harm the engine. think of it as a sound wave in a pipe. if you had a big pipe, the waves would be close together but very high(up and down) eventually turning around and going into the engine(not necessarily).. and with stock piping, shorter waves further apart, leading towards the end of the exhaust...

make any sense? kinda sounds like i just repeated myself a whole bunch of times..lol, i just like examples..

 

[TheRookie]

Goose, You got it exactly right

 

[GooseR]

Goose, You got it exactly right

Sweet! thanks man..