Team Integra Forums banner
1 - 10 of 10 Posts

·
Registered
Joined
·
10,393 Posts
Discussion Starter · #1 ·
is 3.5" over kill? I am gonna go to this place: Federal Mufflers this weekend and get a mederal bent pipe and spray paint it black with ceramic paint, and make it as my intake and call it a day. :) Then add in a custom heatshield (see pic below) with an aluminum sheet. The have it up to 3.5", i am wondering if it will be overkill?

Also, does K&N filter comes in 3.5" as well, if they don't sell 3.5" filter, there is no point for me of getting 3.5" if filter only available for 3".

 

·
Registered
Joined
·
368 Posts
checking K&N's site (http://www.knfilters.com/universal/universal.htm), it seems as if they do have a bunch of 3.5" filters...a lot more 3" ones though, but im sure you wouldnt have a hard time finding the right one. About the intake...what kind of engine do you have? If its a B series, your TB is only 60mm (about 2 1/4 inches). I'm not sure a 3.5" intake is going to fit on there, and i highly doubt your going to feel any difference between half an inch on your intake...
 

·
Registered
Joined
·
10,393 Posts
Discussion Starter · #3 ·
upon reading this link, i am still unsure 3" or 3.5", altho MD does mentioned anything below 3" will only hold back a 1.8L I-4 with 1.5ish rod ratio, once you start building it up seriously... what if i only throw in I/H/E?

edit: ahh... thanks for that K&N filter spec link, very helpful. They do have 3.5" filters.
(F) Mounting Flange Inside Diameter

(F)(D)(L)(FL) (FA)
3555/8Centered
3-1/245-3/4 3/4Centered
 

·
Registered
Joined
·
10,995 Posts
I'll give you the short answer: it's overkill and you could be hurting your performance. Why you might ask?

1st article
This is one written by MD about flow velocity and it's affect on an engine. Read that one first, then look at his one and only intake thread in the perforance forum. It's really useful info.
 

·
Registered
Joined
·
31,217 Posts
the bigger you go on the intake diameter, the peakier the motor becomes. the powerband location is shifted up higher at higher rpms because it takes longer to build up enough pressure to feed into the IM plenum to get peak volumetric efficiency.

peak volumetric efficiency is also called peak torque.
 

·
Registered
Joined
·
31,217 Posts
wanting more midrange is sort of misleading.

the way you approach this planning is to first look at your gearing.

go for a drive to your local strip with a friend.

do a 1/4 mile run and make sure you shift the same way each time. shift at the same redline. have your friend record what the rpms fall down to after each upshift from 2nd->3rd, 3rd ->4th, 4th -> 5th.


the lowest one of these 3 upshift rpm landing points is the start of your powerband.

you want to make YOUR engine's peak torque happen at this rpm landing point or about 200 rpm after it. you fuel tune to ensure that the peak torque stays for as long as it can after this point.


we have a way to calculate the upshift landing point but some people don't like math. and so, this is the practical (and to be honest, more fun way of finding it out for yourself).

Now you know what powerband location you want to start at for YOUR car.

If you swap a tranny or change the overall wheel & tire diameter (notice I did not say wheel) to the point that it screws up the speedometer reading, then your upshift landing point changes. So this is when the math becomes easier method because you can plan to tune your engine and buy the parts for it that make power for that eventual powerband when you can afford to get the tranny or change the overall wheel & tire diameter.

So do you want more midrange to have a faster car? depends on your tranny's gearing. So try not to make too a simple a rule.

A 5-5.7L V8 likes more midrange because it has 400-500 lb ft torque coming in at 1500-3000 rpm. Their tranny/fd is geared for that. look at your motor. it has 125-135 lb ft max. coming in at around 4000 rpm. do you think Honda put your LS' B18B peak torque at around 4000 rpm by coincidence? Do you think the B18B's 1.54 rod ratio which biases the motor to making peak torque at a lower rpm a co-incidence? do you think your tranny's taller gear ratios which lowers the rpm upshift landing point down to around 4000 rpm is a co-incidence? I don't think so. The idea of engine packaging is well known.


Now, do you want a 3.5 in. diameter intake? put it this way, a 1.8L supercharged B18C with 15 psi boost finds that 3 in. diameter is more than enough. You come nowhere near 1/8 of the volumetric efficiency of that motor and so 3.5 in. WOULD BE overkill. The powerband would be so peaky that driving around town at 3000 rpm would be a sluggish boggy nightmare and a Hyundai grocery getter would embarrass you since you never get into your powerband.
 

·
Registered
Joined
·
31,217 Posts
I laugh at GSR and ITR owners who say they want more midrange or this cam is good because it has a healthy midrange for street driving. why? because the GSR and ITR trannies upshift rpm landing points are high at around 5500-6200 rpm. Midrange for an ITR and GSR is 4200-5000 rpm. If they want to go fast, their powerbands have to start at 5500 rpm and not the midrange. So if they buy parts that make power "for a better midrange" they will be slower than someone who is smarter and has worked out the engine and tranny relationship.

1. you want to buy parts that all make power in the same rpm location range.

if they make power at different places, they start working against each other or are fighting against one another. in other words, they are incompatible.

2. you want to buy parts that also make power for the tranny you have.

so those are 2 things beginners don't understand and start buying blindly or based on opinions from someone who has no clue about these 2 basic engine building facts that every racing engine builder knows.


as you learn, you will understand that you have to know the specs of each part because that tells you where it makes its power along the rpm range.

how do you know where the peak torque will come in for a given part, like an intake?

as you do this more and more, you will see dynos and learn which spec (like intake diameter) makes power (peak torque) in a certain rpm powerband location.

that's the whole process of learning engine packaging: powerband location and matching this common powerband location goal for all your parts with the tranny's gearing. the tranny dictates where your engine's powerband starts.
 

·
Registered
Joined
·
188 Posts
Thanks MD. That was a helpful bit of information.

Edit** never mind. I read the article. It's like the holy grail of info. Cousin Chubby on his scooter...lol
 
1 - 10 of 10 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top