ITRCA

Just wondering if by adding a 4-1 header (JDM or DC sports), torque is actually LOST in the low-mid end. Or does it just give none to no improvement over stock headers in that area of the power-band, with a big improvement in the high-end???

Hey Typeruz

I found some information that you might find useful. Here is a link to a header comparison done on the same type R. I found it in the ITRCA's FAQ section under performance mods.

http://www.automotiveperformanceenginee ... eader.html

The dynos show the stock vs new header. I think the answer is that it depends. I think that it is safe to assume that for the most part if there is any loss of torque in the lower RPMs, it is negligible. For example the JDM ITR 4-1 looks like ~3,300 RPM there is a point where the JDM 4-1's torque number dips slightly below the stock number. (see it here: http://www.automotiveperformanceenginee ... DM_ITR.gif )

The DC JDM 4-1 looks to be above stock torque at all times. I am sure that other quality 4-1 headers fall into one of these categories (either losing a little power down low or gaining a little power down low). I doubt any quality (emphasis on the word quality) will lose a noticeable amount of torque in the lower to mid RPM range. This is just an observation. Hope this helps. Take care of the Type R .[/img]

I hope so. I'm putting my stock manifold back on for autocross. DC 4-1 possibly for sale. [/quote]

thanks for the links. it was all very interesting.
i didn't see a dyno for the DC sports NON-JDM style 4-1 header which is what i have. but i'm guessing it'll be similar to the rest of the 4-1 headers, just with less power gain.

take care!

In general a higher flowing exhaust will reduce the back flow and lessen the low end torque. In general a 4-1 is built for good top end power vs low end torque.

It was recommended to me that I use a 4-2-1 if I was interested in competeing in short track races such as Autocross where low end torque will come into play more so than TOP END Power,

4-1 General show no losses although some will show no gains at unusable pints in the RPM band. For the cost the JDM 4-1 is a great header and after tuning the great header test will be inferior data as you will show gains in all areas and significant at that.

Also, more importantly than 4-1 vs 4-2-1 is the collector size of 2.5" found on JDM labled headers.