First off, thank you Akron(Andy) for the header and more importantly the information. He is very easy to deal with and very informative and patience(stayed on the phone with me for more than 30minutes talking about my setup).

Anyways, I purchased the header and noticed that the port that connects to the engine is not smoothed out(ported...? not sure what the correct term is). Theoritically, wouldn't it make sense to port that part of the header so air flows smoother/faster?


BTW, i DID a search and nothing came up.

 

you should have it welded on the outside of the tube to the flange before you begin porting.

Ideally your welder should have a jig of sorts or it might warp the flange as he does the welding.

I'm sure it's covered somewhere.....

 

Yeah Ive heard of peoples breaking after griding the original welds down to "smooth it out" and not welding on the oustide of the tubing, but then you can warp it like RagingAngel said. IMO dont even bother, otherwise you should have just gotten a more performance oriented header, just bolt it on as is.

 

I purchased a used JDM ITR 4-1 header and I ground down the weld on the inside of the exhaust ports (see picture below). I didn't have the ports welded on the outside, that is because I didn't remove an excessive amount. I did remove the majority of the weld which will help the header flow better.

EXHAUST PORTS BEFORE


EXHAUST PORTS AFTER


If you are going to grind down the welds on the header ports, I would also recommend removing the anti-reversion piece in the collector (see picture below). This will also increase flow.

COLLECTOR BEFORE


COLLECTOR AFTER



Modified by BSQ at 12:46 PM 10/18/2005

 

Anti-Version? how would this increase flow unless im missing something it seems to be maybe an 1/8" smaller then the outlet which may not be a bad thing consdiering most 4v 4cyl engines are going to want a slightly smaller collector outlet then the tailpipe anyways

oh and as far as welding the outisde goes i wouldn't worry about warping it, it should be a mild steel flange which if you get it hot enough to warp is not going to warp very muhc if any at all

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Casey@Burns &raquo;</TD></TR><TR><TD CLASS="quote">Anti-Version? how would this increase flow unless im missing something it seems to be maybe an 1/8" smaller then the outlet which may not be a bad thing consdiering most 4v 4cyl engines are going to want a slightly smaller collector outlet then the tailpipe anyways
</TD></TR></TABLE>

It should be anti-reversion (I corrected it in my reply -- sorry about that).

I measured the inside diameter before (~2.0") and after (~2.25"). If you calculate the area of the opening before (2.0" = 3.142 sq. in.) and after (2.25" = 3.976 sq. in.) that would be an increase in area of 26.5%.

 

are you sure the header needs that large of an area

 

bigger is not always better

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JakeIsCool &raquo;</TD></TR><TR><TD CLASS="quote">bigger is not always better</TD></TR></TABLE>

The removal of the anti-reversion piece in the collector of the JDM ITR 4-1 header makes the collector size no different than the DC JDM 4-1 collector or for that matter, all other aftermarket headers with a 2.5" collector (eg. Mugen, Toda, Spoon, Hytech, SMSP, etc.).

 

If you're going to start nit picking small crap like that



60mm is not 2.5", most of the Japanese aftermarket Honda exhaust components are right around 60mm, which

2.5"=63.5mm

60mm=2.36"

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Chaze*R &raquo;</TD></TR><TR><TD CLASS="quote">BTW, i DID a search and nothing came up.</TD></TR></TABLE>
:shrugg:

http://www.sandmracing.com/m_e02_jdmheader.html

 

IMO at the price he paid, $85 for welding, $15 for the grinding stuff, and however much on the Jet-Hot like coating I would have just saved a couple extra bills and gotten a Toda or something.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by KOALA YUMMIES &raquo;</TD></TR><TR><TD CLASS="quote">If you're going to start nit picking small crap like that



60mm is not 2.5", most of the Japanese aftermarket Honda exhaust components are right around 60mm, which

2.5"=63.5mm

60mm=2.36" </TD></TR></TABLE>

It says the following on Toda's website ( http://www.todaracing.com/prod....html )..."This header features a larger JDM 2.5 inch collector for maximum power and is for off-road use only!". So I'm betting that the 60mm (2.36") is the inside diameter.


Modified by BSQ at 8:53 AM 10/19/2005

 

Yes and its been discussed in other threads in here that the sizing is "close enough" in that the manufactuer just says 2.5" because its "close enough". Unless you want to measure whether is ID or OD theres really no point in arguing it. My point was, does it really make that big a difference, and as others pointed out; is the difference better or worse?

 

Well more then likely honda didnt intend for that to be an "ANTI-REVERSION" device, it's more of a device of manufacturing.

header science 101 using the toda as an example

The collector outlet is crucial, the collector outlet is not the exhaust size the collector outlet commonly reffered to as the choke is positioned on the toda header right at the beggining of the "taper" design.

The reason this size is "choked down" is to promote scavenging in the engine. Without going into too muhc detail collector outlet size is calculated from a variety of inputs such as bore, stroke, valve, size, camshaft, features, port size, etc.

A stock type R engine is going to want a collector choke size of near 2-1/8" with a transition up to 2 1/2" for the tailpipe. So as you can see this is a ways off from 2-1/2" Pro All Motor cars need a collector choke of around 2-1/2" to give you an example.

Chances are it's not a big difference and if it is it's probably 1-2 HP up top and losing a bit on the bottom. Tubing SHOULD ALWAYS BE MEASURED IN OD OUTSIDE DIAMETER.
Therefore you usuall assume loss of 1.8" due to wall thickness.

in otherwords a "2-1/2 collector" is pretty effin big for a street car.


Hope this helps

 

I've done this mod many times.

If you are careful with the removal of material from the ports you do not need to weld the outside of the tubes, just remember (with all materials equal) the weakest part of the joint is the thinnest. If you do weld it, you shouldn't have a warping issue either since this is a 1 piece header.

As for collector size, the JDM headers have collectors outlets at 65mm OD (2-9/16"). Most of the stuff I build for B and H series will have a 2-1/2" OD outlet. The Toda has a 65m OD outlet but I seem to remember that the collector may be double walled but no volume area like the OEM ITR JDM header.

When the inner wall is removed from the OEM ITR JDM collector the throat of the collector is not changed.

I've never done a back to back but I've been told that you can see up to 3whp with no loss of mid range. Increases will also be dependent on the initial power outputs, larger higher hp engines will see bigger gains.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SMSP &raquo;</TD></TR><TR><TD CLASS="quote">
I've never done a back to back but I've been told that you can see up to 3whp with no loss of mid range. </TD></TR></TABLE>

ummm.......lol

oooooooooooooooo......3hp.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Casey@Burns &raquo;</TD></TR><TR><TD CLASS="quote">Therefore you usuall assume loss of 1.8" due to wall thickness.</TD></TR></TABLE>

Damn thats some thick piping! Thanks for the info

 

1/8"

you knew what i meant!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Willard &raquo;</TD></TR><TR><TD CLASS="quote">
:shrugg:

http://www.sandmracing.com/m_e02_jdmheader.html</TD></TR></TABLE>

I meant that I did a search using the HT database. However, good link.

I'm sure glad I asked though. I got great responses. Thanks guys!

My friend will be helping me on smoothing out the ports.