Ok,
This is my theory, please tell me where I am wrong....
Currently I am having Dave at KD rotary rebuild my engine with a 2nd level streetport, in my discussions with him, it was determined that the following items will added the following amounts of horsepower:

• StreetPort = 15 to 20 hp cost = 1600 bucks (part of the rebuild)
• downpipe = 10 to 15 hp cost = 300 bucks
• intake = 5 hp cost 485 bucks (M2 intake)

Now putting aside the cost of the porting, which really isn't 1600 bucks, but since you have to do it while the engine is apart, we'll leave it at $1,600.
My thing is this -> the intake for being such a high dollar cost really doesn't help that much! Look at your cost per hp

• Streetport (1600/20) = $80
• Downpipe (300/15) = $20
• Intake (485/5) = $97

This is crazy!!!!!
Tell me how I am wrong with this, please!
Thanks

 

the thing is that just adding an intake gives 5 hp but putting an IC or exhaust won't gain all their hp potential if you do not get more air in with an intake.

it is like upgrading only the exhaust, you get more air out but you don't get air in, you won't gain all the hp potential that you could have for the exhaust

puma

 

I still don't see the point of an intake tube.

Already, the stock ducting is larger in cross section than the throttle bores, so where is the advantage? It can't be from increased area. I have grave doubts about "straightening the airflow" because there is already a good measure of designed-in turbulence in the intake manifold, and besides, the throttle blades will screw up how "straight" the air is anyway. The only advantage could be from a less restrictive filter/lack of airbox restriction - and that can be fixed with some time, ingenuity, and a Dremel.

I also don't see only a 20hp gain from a street port, unless that's 20hp if ONLY a street port is done and nothing else is changed - but who in their right mind would street port an engine and put the stock exhaust on it?

 

Oops, just realized this is for a turbo model... but the same theory still holds... if the intake duct is larger than the turbo inlet, making it even bigger ain't gonna do much of anything!

 

I 100% agree that the main advantage to modding an engine is to allow it to breathe better. But if the intake helps the potential of all the other mods, why does it add so few horsepower? If it is indeed the bottle neck, then it should be like the downpipe and add a lot more hp. Anyways I've been looking around at a bunch of different intakes and I have read all the post on this forum.
The M2 is too expensive 485, but it is one of the only air boxes I would get, because all the others look so getto! Yeah that pettit box, looks like it should be in a dirt track car. Functional, but no form.
Please don't flame me on this stuff, I'm just trying to determine if 485 dollars is worth replacing the stock air box...

Oh and peejay,that was a good point about the throttle body, I had never looked at it that way before. And the point about adding hp with the streetport, I think it's possible, because you are actually changing the timing of the engine as well as opening up the breathing abilities.
just my .02

 

I don't think you can compare the throttle body opening directly to the intake opening since it's sitting on the other side of the turbos (compressed air). I do agree however that the intake add little power for the money. Personally, I think they are overpriced too. The only reason I would buy one would be to make room in the bay for a larger intercooler which cna really make difference in power.
-Mike P.

 

Someone best explained it as the intake allowing the full potential of other componants. Here are some fake numbers, but you'll get the idea:

Just Street Port: 20 HP
Just Down Pipe: 15 HP
Just Intake: 5 HP

Street Port + Intake = 50 HP
Downpipe + Intake = 35 HP

Street Port + Downpipe + Intake = 75 HP

See?

~Tom

 

I agree....just adding an intake won't give you much of a rush when you hit the the gas but everything on a car compliments the other.

Another example would be getting a DP and no midpipe or exhaust. The DP sure won't do much with the rest of the exhaust choked up like that.

 

All good points, except I don't see the advantage to a 485 dollar M2 intake system. I also don't see the pettit and other systems preventing hot air from getting into the air intake system...
Now I know that this seems cheeze but I will put it out here for your review. What about using the Racing Beat air intake ABS tubing, and doing some dremel style moding to the stock air box... Along with a K&N stock style air cleaner?
I think that this would give you the best of both worlds???
I'm I wrong here?

 

Well, aircleaners HAVE been dyno proven to provide 10+hp
When I installed mine, I DID feel the differance. Enough to feel a LOT better than just a 5hp increase...

Saying that an aircleaner will only give you 5hp increase is a conservative number. In ALL my years of being a car nut, I've never really known an aircleaner to only give 5hp.

 

Ok,
Well that sounds like a positive statement. Please enlighten us to the type of intake that you installed on your Rex.
TIA

 

Buy my HKS power flow intake for 95.00 and then it wont be so expensive.

 

I read in a shootout that APEXi was the best, lemme try and forge that shootout out of my favorites

 

http://www.gtrowner.com/induction.html

 

You have to chose the right intake for the other mods that you are going to do too. If you are going with a large SMIC, like the M2, you are going to need an intake similar to the Pettit or M2, because physically there is no room for the stocker and some of the aftermarket units (like the Apexi).

I have an Apexi and an older style M2 (metal, not CF). Differences between the two? Haven't dyno'd each, but I did not notice anything substantial on the butt dyno. The M2 intake is noticably quieter than the Apex (Apex has a strange resonance, almost a growl at certain RPMs). I did not notice a difference in intake temperatures either (as monitored by the PFC). Even though the M2 is sucking fresh air in from the front of the car, not the engine compartment like the Apex. But the intake temps monitored on the PFC will be more dependent upon the quality of the intercooler, and if you don't have a good enough one, then it doesn't seem to matter if you have a cold air intake (based on my experience I seemed to have the same boost pressure and response). I think that the Apex filters are better than the K&N (on the M2), but I have no evidence to support this.

The keys (IMO) to picking an intake are good filtration and how well it physically fits with your other planned upgrades.

Sorry, long post, got a little off track. Just my $0.02, if you want to get the most HP per dollar, make sure that you get the parts that are going to work with the rest of your upgrades.

 

i made my own intake out of pvc(the famed TID mod) and it made a noticeable difference in power. it cost me next to nothing(my dad is a plumber, i have pipes laying around my house) and i felt an increase in power. thats all that matters to me. i may buy an actual intake kit one day, but only cuz the pvc one doesnt look lean enough

 

Just rambling. On my 87TURBOII, by just adding the Mazdatrix 2 and 1/2 downpipe and presilencer(the ***** setup) and nothing else, I boosted to just shy of 8psi. Last week I took the K and N off my 87N/A and put it on the turbo. Now I'm hitting a solid 10psi(and fuel cut). So I've gone from bad mouthing the K and N to saying, *well I'll be darned*. Just my four cents.

 

Matt,

about the M2 air box and the dollar to HP ratio your coming up with. You don't have to get it, meaning there are other air boxes of similar enclosed design that are a bit cheaper. As to the 5 hp, thats really a very low number. But like others have posted , you'll need some sort of intake to take real advantage of the porting and more open flowing exhaust.

A friend in our local club, Damie (red FD, big wing, white stck wheels), did what you mentioned. He has a DP, MP, and a muffler cut into the stock piping of the stock cat-back exhaust. He dropped a K&N panel filter into the stock air box and cut out the bottom middle strip to sort of coincide with the side opening like air boxes use beside the radiator. He's making plenty of boost and also HP with his Pettit chip and dawes device boost controller so that could be an option to go with if you wanting to get the best HP/$$ ratio with an intake.

Tim Benton

get the car ready for our next meet!!!

 

An effective cold air box does not have to be expensive. I'm really impressed with what has been done by others to modify the stock air box. Here is a link to some pictures posted by member wickedrix not long ago:

http://briefcase.yahoo.com/bc/wicked...c=bc%26.view=l

You may not want to do the modification exactly like this person did, but at least now you can grasp the concept and come up with your own design. In the end you'll have the satisfaction of do-it-yourself fulfillment without a big hit to your wallet.