Hey guys. My question is in regards to having a machine shop port my intake manifold. About 3 months ago now, I had the MPx 60mm throttle body installed onto my 2000 dodge neon automatic. And to be honest with you, unless I am in full throttle, the throttle body makes performance worse, or atleast it seems. The car wants to get ouf first gear to quick when just casually driving and causes the transmission to kind of jolt foward and click into 2nd gear way too soon. Also, when I am in at moderate acceleration making my way up the powerband on the rpm gauge, it will cause the neon to suddenly drop off at 3 1/2 rpms and switch to 3rd gear which sucks because 3 1/2+ rpms is right where the neons start to make its push. So, i've heard online that the throttle body was actually going to make performance suffer until i allowed my relatively non active intake manifold much more flowing. If i had a machine shop port my manifold, would this make it so my throttle body could become somewhat useful, and not damage my performance. I just found it a little discouraging that I spent $265 on a mod that actually made my neon slower than what it was before lol! Anyway, get back to me guys, I want to know if the porting of my intake manifold will let the car breathe, the car sounds like its getting flooded up with too much air when i kinda step on it without slamming it, just sounds too cloggy, worst than it did before. Thanks guys!

 

which manifold do you have? A stock plastic intake manifold I would re-frain from trying to port match.

The intake monifolds on neons suffer from a quality standpoint. They are plastic....

So, I would suggest saving up and spending the money on a custom intake manifol, finding an R/T Intake manifold and porting that, or the INDY intake manifold.

I suggest the custom intake manifold or the R/T manifold personally. The INDY is a PITA to install... it syas direct bolt on... but it is no where near that simple.

 

What you percieve as a loss of power is a slight low end loss of torque. Port matching your stock intake manifold will not give you back any gains either because of the restrictive flow of the standard SOHC head, besides the fact that you cant port the plastic manifold. Your best bet is to find a Magnum head (and cam)and Magnum intake manifold and port the manifold accordingly. There are few intake mnifolds that perform better then a ported Mag Intake manifold. If you donmt want to do a headswap, get a fully functional Magnum intake manifold and wire up the secondaries, that will help get back some of that low end torque. Add a Mag head, and you'll gain a little as well...

 

so does that mean that the bigger throttle body isn't that great of a mod unless you do all that other stuff? or am i misunderstanding

 

sounds like it bro......in order to utilize all the extra airflow you are getting from that throttle body you need at least a cam...the head and intake manifold would be the plus...but at least the cam...

 

Not really. The car really needs it on its top end power band. All the torque is up past 3500 rpms. With mods such as an intake manfold and a ported and polished head will brin back a lot of torque on the low end, but at the same time the high end torque is going up as well.

I like to think of it as this. No matter what you do, you are exponentially increasing your high end torque (which the car needs anyway) but you are pulling away from and slightly adding to your low end torque.

A camshaft does wonders with a new throttle body, but so did the car before the cam with the throttle body. I do a lot of highway driving, and getting up to speed at higher rpm's was NO problem.... for an automatic neon anyways[8D]

 

Well from a budget standpoint, and from my parents standpoint, they dont really want to see me putrting anymore money into this car, lol. DO you thin it'd be wise to just get over it, and live with it? I cant put anymore into this car as much as id like to. I've put in over 4,500 dollars already, its just rediculous lol. And i still have to get tires for my rims and lowering springs. After that, i think ill just be done, and keep after maitnance and just be happy with this already very custom neon, im going to into collegesoon, and i need to start saving my money, i cant keep living off every paycheck haha. I am very happy with what i have done to this car, looks, and performance wise, i just thin itd be wise for me to finish up what id like to do, and then just start taking care of the car, and having money again haha! Thanks guys for the advice though....

p/s: If i just bought an r/t intake manifold without doing the head, would it help out, or do i have to do the whole shabang including the camshaft??

 

I'm thinking that the oversized 3 inch downpipe isn't doing anything to help performance, expecially in the low end. It might be hurting the performance. What do you guys think?

I've heard that the 60mm tB will hurt performance in the low end but increase performance in the top end. I have the MPX 60mm tb and it seemed that way with me. I'm not exactly sure what mods I had on my car at the time though.
Other than that, it's up to you if u want to put more money into your car. If you're willing to put more money into your car, an upgraded cam would compliment the TB very well.

 

When u push your car to it's limit, about what rpm does your car shift at?

 

Well, you cant look at your engine as individual components, you have to look at it like a system. For example, you buy a cold air intake, ok, great, your getting colder, more dense air into the intake system. However, you have a restrictive throttle body, intake manifold, and cylinder head that dont exactly flow that great. So you buy a 60mm TB, now your allowing more air into the system, getting greater throttle response, but loosing low end power. So you install a Magnum intake manifold, thats great and all, but you still have the road block that is the poor flowing cylinder head (compared to the Mag) . So you buy a new camshaft, well thats great, your lift and duration is much better then before, but you still have a poor flowing head. So you race port and polish the head or install a Magnum head, now your intake side is flowing like the Ohio river. Problem is, your exhaust side is too restrictive, so you need a longtube header and free flowing exhaust.

See when your modding your car you cant just throw some stuff on here, and some stuff on there and "hope" that your modifications will give you gains. You have to build on each particular aspect of the engine and do modifications that will help the other mods you have already done (i.e. supporting mods).

Make sense?


You would be correct, the 3" downpipe and 3" cat are not helping performance at all, and are probably contributing to the loss of low end torque. Your also right that while you lose low end torque with a 60mm TB (on stock everything else with a standard SOHC), you gain top end power and get increased throttle response.