4-1 vs. 4-2-1 for D16A6

[Mr. Noodles]

Am in the midst of purchasing a header for an IT spec '89 CRX Si. Stories are conflicting concerning whether or not the D series motors will benefit from a 4-1 like the B series ? Is the top end gain on the 4-1 worth the relative loss in midrange compared with a 4-2-1 setup? http://Forums.ImprovedTouring.com/it/confused.gif Preference on brand ? Had planned on running a 2.5" pipe from the header back.

Thank you,

Robert J.

[This message has been edited by Mr. Noodles (edited January 17, 2004).]

[jc836]

We are using a DC Sports 4-2-1 header and a high flow CAT. This is followed by a long resonator and turn down. The tubing is 2.5" from the collector back. So far I have not noticed any real difference in performance from 3500-7000.
The components behind the collector are there because the car remains street legal.
What is also important is that one must Dyno the car to determine what is happening. DC products have been tested a number of times.

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Grandpa's toys-modded suspensions and a few other tweaks
'89 CRX Si-SCCA ITA #99
'99 Prelude=a sweet song
'03 Dodge Dakota Club Cab V8-Patriot Blue gonna tow

[Tyson]

high flow cat?

[jc836]

As in convertor-required for street cars. We have not yet yanked all the pollution stuff off. That is why it is there. It is also a benefit as it acts as a sort of resonator too.

------------------
Grandpa's toys-modded suspensions and a few other tweaks
'89 CRX Si-SCCA ITA #99
'99 Prelude=a sweet song
'03 Dodge Dakota Club Cab V8-Patriot Blue gonna tow

[Mr. Noodles]

Originally posted by jc836:
We are using a DC Sports 4-2-1 header and a high flow CAT. This is followed by a long resonator and turn down. The tubing is 2.5" from the collector back. So far I have not noticed any real difference in performance from 3500-7000.


When you say you have not noticed any real difference, are you comparing the current setup to the oe configuration? I have heard that the oe setup works [ outside of the restrictive cat ] well for an IT spec head. I have no experience with the D16 and appreciate any feedback. http://Forums.ImprovedTouring.com/it/smile.gif

Thank you,

Robert J.

[jc836]

I cannot say for sure since we ran the car with the full stock exhaust initially. The engine does rev a bit more freely, in my opinion, with the DC and setup we now have. Again I have no dyno data and have not run the engine without a CAT. Sorry if this a bit vague-there are others here with far more serious setups that can answer too.

------------------
Grandpa's toys-modded suspensions and a few other tweaks
'89 CRX Si-SCCA ITA #99
'99 Prelude=a sweet song
'03 Dodge Dakota Club Cab V8-Patriot Blue gonna tow

[airpiraterob]

i posted a response to someones post titled "need more top end" or something like that. I included a link to some dyno charts of before and after. the guy used a Bisimoto header on an utterly stock D-series 1.6 motor. these gains were throughout the RPM band and especially in the ranges you would be running. the engine used had many many miles on it and slightly enlarged exhaust ports already. its a stepped tube design using pressure waves and all that for scavenging....etc....despite the price, people swear by them! plus a really cool bundle of snakes is hard to beat. its a 4-1 with the curves and shapes made by science not just equal length alone.

ah, here it is. a message board post about the header and the experiences the lucky owner had with it.

http://pub161.ezboard.com/fbseriesalternat...picID=283.topic (http://pub161.ezboard.com/fbseriesalternativefrm7.showMessage?topicID=283.to pic)

the guys website. he is working now on a design that acts like a 2-stroke pipe for a 4 stroke car. using all kinds of black-magic. he is extremely well respected in the field.
www.bisimoto.com (http://www.bisimoto.com)
[This message has been edited by airpiraterob (edited January 19, 2004).]

[This message has been edited by airpiraterob (edited January 19, 2004).]

[Mr. Noodles]

Thanks for the update on the Bisimoto header. I've seen one similar, by AR-N. Both of these models use equal length serpentine headers that look like something off a F1 car. Cost is usually 2-3x the going rate for conventional 4-1's and I'm curious as to their impact versus conventional. I'd pay the price if I could find some dyno comparisons.

I'll let you know what I decide. Thanks again for the feedback.

Robert J.

[Fleetcare]

I had 4-1's, I liked the way they felt more "online" than the 4-2-1's i replaced . The power band area to me felt better with 4-1 Mugens!

[R2 Racing]

I have been doing a similar search for the B-series engine. What gives the most horsepower? What I've found is pretty similar to what you guys have talked about: Bisimoto, AN-R, HyTech, or SMSP. Only problem is they're sooooo expensive - best in the biz though. They're customers swear by them.

Bisimoto B-Series header:
http://www.automotivetech.org/photopost/data/520/8475bisibnew1.jpg
Bisimoto D-Series header:
http://www.exospeed.com/pictures/bisiheaderfront.jpg
Bisimoto D-Series Header Dyno Plot:
http://www.exospeed.com/pictures/bisiheaderdyno2.jpg
AN-R Standard B-Series Header:
http://www.an-r.com/images/stand2.JPG
AN-R Compact Version B-Series:
http://www.an-r.com/images/DSC03860.JPG
AN-R D-Series Header:
http://www.an-r.com/images/dheader.jpg
AN-R merge collector (badass):
http://www.burnsstainless.com/MergeCollectors/cutaway_big.gif
AN-R H-series dyno plot (all I can find, sorry):
http://www.an-r.com/Hdyno.jpg

[This message has been edited by R2 Racing (edited January 23, 2004).]

[This message has been edited by R2 Racing (edited January 23, 2004).]

[Hracer]

We've used the 4-2-1 DC header before - it's a good header. Three years ago we tried a 4-1 header done by Walt Puckett at Delta Group Motorsports. We've ran it on the dyno and have been running this unit on the track since then on two different ITA CRXs. I highly recommend it. Quite a few other Honda IT racers use this header. It is great for top end (especially after 6K) and that's exactly what is needed to make the d16 fast on long straights. Get this header from www.opmautosports.com (http://www.opmautosports.com) or from Walt Puckett at (704) 434-8046. Good luck.

------------------
Alex
#2 ita

[Jon Nelson]

Hracer....

What sort of results did the Pucket header give over the DC sports 4-2-1?

I have a DC sports header, I cut off the smallish outlet at the collector and welded on a 2-1/4" stainless tube, a braided flexjoint, and stainless 2-1/4" tube to a supertrapp at the back.

I'd be REALLY interested in real numbers comparing these two headers.

Thanks!!

[metalworker]

Jon,
Different engines and exhaust systems have an effect on the outcome, but generally we see a 2-3 hp gain over the DC. The biggest difference we see is the engine continues to make power at higher rpm.

Walt

[il8apex]

I think I just shorted out my keyboard, drooling over all those pipes!!!!!!

-T

[Jon Nelson]

So, 2-3hp peak... assuming about 6k rpm.

What sort of gains, then, at 6500? 7000?

7500? http://Forums.ImprovedTouring.com/it/smile.gif

Thanks,

Jon

PS - Since you've no doubt played with this, what would the "ultimate" exhaust for the D16A6 motor be?

If you want to keep at a secret, you can email me at [email protected] http://Forums.ImprovedTouring.com/it/smile.gif

[volante]

Horsepower this horsepower that--dyno this dyno that--The real skinny is the DC SPort 4-2-1 is an overall good header,better suited for a short twisty track,OPM's 4-1 or a simular header is about 2-3 car length's faster on the medium to long tracks.You really will not notice any difference until you get on the straight's.One thing to consider is that if you like to leave the cement alot--the 4-1 does' not fit under the car as well.The 4-2-1 fits much tighter to the oil pan with a little more ground clearance.

AND---you have to do a few more things to the car to gain any of the power from that header($450)--about $300 for the DC Sport) which is a upgraded ECU,new final drive,etc.
The only way to keep up with the fast Honda's is do everything to the car that you can and drive that MoFo like you "stolt it".

D.V.
former CRX'er--currant SM driver

[ErnieJ]

I can't find an address or web site for Bisimoto headers.Can anyone help. Thanks!

[R2 Racing]

Originally posted by ErnieJ:
I can't find an address or web site for Bisimoto headers.Can anyone help. Thanks!


www.exospeed.com (http://www.exospeed.com) & click on the Bisimoto Header section (top right)

[ErnieJ]

Originally posted by R2 Racing:

www.exospeed.com (http://www.exospeed.com) & click on the Bisimoto Header section (top right)

R2
Thanks for the help finding Bisimoto.

[SMSP]

2-1/2" is too big for an ITA D16A6 engine. A 4-1 can be built to gain torque in the mid range while also picking up horsepower int he upper range.

[Geezer]

Just got my H4 CRX back after a refresh and some tuning. The motor is pretty much full ITA spec, with an SMSP 4-1 header. The Dynapack chart (sorry, not hosted yet) shows I'm running 90% of max torque from 3000 rpm up, with the torque peak at 5700. The tuner commented on the strong midrange and hp numbers we were getting.

[exospeed*com]

Let me clarify something.
The Bisimoto header and the AN-R may look the same. but the Bisimoto is the only one that USES the Burns Collector. At this time, the Bisimoto has always been using the Burns collector in all its designs.

The Bisimoto header is available in B, D, and H series engines. and options are Street(with 2.5" exit pipe), Race(with a megaphone style exit pipe)and in Jet Hot Coated or Uncoated versions

any questions, feel free to contact us at [email protected]
thanks
Wil

[exospeed*com]

http://www.exospeed.com/pictures/bisidcoated2a.jpg

[This message has been edited by exospeed*com (edited February 18, 2004).]

[Danny M]

Has anyone dynoed the DC 4-1 on the D16? I know there is not a fitment listed but it is what I am using now in Solo II. I haven't had a chance to dyno yet but it sure does feel good above 4500.

[Jon Nelson]

A DC Sports 4-1 on a D16?

What fitment is listed? Ie, what do you have it on, and what is it supposed to be on?

J

[Jon Nelson]

Duh... found it. At Summitracing.

So, it's supoosed to fit 92-95 Civic. How well does it fit on the 88-91 Cars? Ground clearance OK?

Thanks (again),

Jon

[Danny M]

I found out the hard way BUT....

You need to take out the front cross member and front engine motor mount as well as the rad fan in order to have enough clearance to get it in. Stock manifold goes out through the top, 4-1 needs to go in from below. Then, the bracket on the header (on what would have been the secondary pipe on a 4-2-1) will bump into the oil pan before you can get the header up and around the head studs. So, you need to trim a bit of that bracket to slip the header onto the head studs then custom fabricate a bracket to make the factory hanger meet up to the hanger on the header because its in a different position.

Aside from that it bolts right in! I was told that the 4-2-1 does not have much of a power advantage over the stock Si manifold and that the 4-1 would be the way to go. I haven't tested it yet on a dyno, but that'll be soon. As for clearance, I'm running the car in Solo II in the STS category and the car is lowered with the tires (205/50-15) flush with the fenders, or 4-1/2" to the jacking points. I haven't had any clearance issues.

[Tyson]

danny, an aftermarket 4-2-1 certainly DOES have an improved gain over the stock exhaust manifold on a D16a6 which is 4-1 with very short primaries and a tiny and long collector pipe. on later d16 civics however, like the D16Z6, honda changed the stock design to 4-2-1 already, so for those engines, the gain is not so big since the design is already the same. but ive read some gains in just increasing the collector size on the stock Z6 manifold.