New/Modified Header Design?

Daryl Smith · Post by **Daryl Smith** » Fri Mar 11, 2005 9:27 pm

3. What do these gains cost?

There will be a moderate, but noticeable (one time ) drain on your wallet!

( Unless it causes you to be more heavy footed!!)

Post by **dbrick** » Sun Mar 20, 2005 11:23 pm

The crankcase evac is a big thing with dragracing guys. The slash cut tubes go in the exhaust and then some unknown force does impossible things while expanding in all directions equally except for the direction it is going where it expands more except when it is traveling backwards up another tube sometimes actually going through the motor twice.(EGR?).

Sorry, couldn't resist was reading all the opinions, including mine, all of which make more or less sense depending on where you start reading. I freely invite all to make fun of my opinions too. I think we all have a piece or two of the puzzle. Proof is on the dyno or in the wallet depending on your priority.

http://www.paceparts.com/index.asp?Page ... odID=62414
Good news is one kit will do 2 inline engines.

Serious now.
The crankcase evac will create negative pressure in the crankcase because it has no air inlet you need a sealed oil cap and dipstick. The exhaust is reputed to cause a suction via the venturi effect of the slash tube in the airflow, the 2 valves are antibackfire valves for obvious reasons. I assume it will not be very effective at idle, but maybe no worse than the factory system, but could make a difference at high rpm.
Theory being negative pressure = less air resistance on crank and less pressure pushing oil past the rings. Alot of drag engines have them, so I'm guessing it works.

Post by **S Allen** » Wed Mar 30, 2005 4:06 pm

Some one posted this to the Roadster List. It is a pretty good read on exhaust theory and myths.

http://www.nsxprime.com/FAQ/Miscellaneo ... theory.htm

Enjoy!!

Steve

Cobra Tim · Post by **Cobra Tim** » Mon Apr 11, 2005 5:58 am

OK guys.. Im sure you will love this.

Here are pics of the ORIGONAL BRE header I sand blasted (Took me several hours) and painted. This is off the Blue BRE car Frank drove in the late 60s. We have the car and its currently in a development/rebuilding state.

This header is slip fit. Every primary fits loosely into the collector and requires copper RTV for a proper seal.

http://tinypic.com/2nvgxi
http://tinypic.com/2nvh9l
http://tinypic.com/2nvhap
http://tinypic.com/2nvhbc

*NOTE* Thats not the BRE car in the pic. Im have some shots of the car on my camera and need to get them hosted.

SLOroadster · Post by **SLOroadster** » Mon Apr 11, 2005 9:33 am

Wow that thing is a monster. I'd still be interested in running one like that. It would take some creative effort to get a flex tube on there, but I bet it sounds awesome, and for those of us who run hot U20s I bet there is some HP to be found.

Will

Cobra Tim · Post by **Cobra Tim** » Mon Apr 11, 2005 9:42 am

One of the primaries actually goes over the top of the frame, and unfortunately the body support needs to be notched quite heavily. IÃ¢â‚¬â„¢ll try and get detailed pictures of the header installed on the car. Another crappy thing about this header is the ground clearance. The first thing to hit WILL be the header. We actually had to replace the last 6 inches on each bottom primary due this problem.

DELETED · Post by **DELETED** » Mon Apr 11, 2005 11:06 am

DELETED

Cobra Tim · Post by **Cobra Tim** » Mon Apr 11, 2005 11:11 am

alving wrote:Wow that header looks beefy...do you have any pics of the car in pictured?

No, but the next time I get to the shop Ill snap a bunch of the two roadsters.

The BRE car needs ALOT of work. We have been spending most of our time developing the new motor. The body is in horrible shape and need a lot of attention, but its coming along slowly.

Post by **dbrick** » Mon Apr 11, 2005 5:11 pm

Wow, nice, must be a mother to get in, unless there are no inner fenders.

The collector looks alot like the one I posted on page 1 of this LONG thread, except it is 4 into 1.

That would be a nice part to somehow get manufactured (3D CAD??)
For the serious horsepower junkie, it eliminates alot of problems running large exhaust through the X member. Added bonus you get to hear more exhaust noise with the tailpipe right below your left ear.

Cobra Tim · Post by **Cobra Tim** » Tue Apr 12, 2005 8:07 am

dbrick wrote:Wow, nice, must be a mother to get in, unless there are no inner fenders.

The collector looks alot like the one I posted on page 1 of this LONG thread, except it is 4 into 1.

That would be a nice part to somehow get manufactured (3D CAD??)
For the serious horsepower junkie, it eliminates alot of problems running large exhaust through the X member. Added bonus you get to hear more exhaust noise with the tailpipe right below your left ear.

ItÃ¢â‚¬â„¢s a pain to install, but does it make a difference. On the Vintage car, the header was such a bottle neck that the pressure would create so much heat that the coated headers would glow red hot. A hot E production motor really needs a set of headers like this to flow to it full potential.

I donÃ¢â‚¬â„¢t know much about these roadsters, but my Uncle (the owner of the cars) has had them since the late 60s early 70s. I guess you could call me the chief mechanic even though I know very little about this older technology. IÃ¢â‚¬â„¢m at a bit of a learning curve but as the weeks and months progress my knowledge of Mikunis, points ignition, and antiquated suspension technology is growing exponentially.

We are racing on a budget and I plan on starting a thread with detailed pics and information on our progress.

Daryl Smith · Post by **Daryl Smith** » Fri May 13, 2005 12:36 am

From Ronnie Day on the roadster email list:

"Thought the group might be interested in the info that David Vizard, one of
the more highly regarded writers on air flow and engine theory, is a regular
contributor to Popular Hot Rodding. While some of the discussion in PHR
focuses on domestic V-8s, most if not all of it is applicable to all
internal combustion engines. In the May issue there's an excellent article
on exhaust systems. If you get air & fuel in, then you gotta get it out.
It's all about flow.

I also just pulled the new GRM out of my mailbox and Vizard has an article
in it, too. The guy definitely knows what he writes about, IMHO.

FWIW,
Ron "

I agree and have read a bunch of Vizards stuff. I have this article and while it has some interesting information, I am still trying to figure out how to use the graph called Fig. 4?
Also if you look you will see the crankcase ventilation systems on the engines on page 58.

Daryl Smith · Post by **Daryl Smith** » Mon Jul 18, 2005 4:40 pm

Found this picture in the Competition Manual of a U20 header.
Fig. #4 page 27
http://www.datsun.org/roadster/info/dcpm11.pdf

Similar to what I had in mind for the stroker engines. But with longer primaries, smaller pipe (possibly 1 3/8" - 1 1/2" - 1 5/8" ?), and better collectors. Slightly longer overall than the currently available header.

Cost would depend on getting a quantity made. Singly they will be quite expensive. If a quantity were made cost could likely be brought down significantly.

To quote a freind of mine: "You will never turn a pig into a racehorse. But,
If you beat it hard and long enough, you'll have a really fast pig."

No offence intended, but.... I want a faster pig!!

(when compared to modern engines....)

Daryl Smith · Post by **Daryl Smith** » Thu Jan 17, 2008 10:54 pm

Ok, I'm finishing up on most of the other "upgrades" to the car and it is FINALLY time to build the header.
Do any of the vendors sell a 1/2" thick flange for the 1600? I'd prefer to start with this rather than have to get one cut myself........

Barring finding one from a vendor, is anyone else interested in a flange to build their own custom header if I get some cut????

SLOroadster · Post by **SLOroadster** » Fri Jan 18, 2008 10:39 am

Daryl Smith wrote:Ok, I'm finishing up on most of the other "upgrades" to the car and it is FINALLY time to build the header.
Do any of the vendors sell a 1/2" thick flange for the 1600? I'd prefer to start with this rather than have to get one cut myself........

Barring finding one from a vendor, is anyone else interested in a flange to build their own custom header if I get some cut????

I might be. I picked up a 1 5/8 version of the common one, but I'd really like to do a long tube version (like the BRE one). Let me know how much one for a U20 would run.

Thanks,
Will

wvitPR · Post by **wvitPR** » Fri Jan 18, 2008 5:43 pm

Hi All,
I have just finished a set of 4-2-1 extractors for my restoration that I tried to design around roadster frame restrictions. It soon became apparent that trying to get the appropriate length for the secondaries is always going to be a problem because of the x-member, so I modified the x-member and managed to get the following;

Primary's - 18 inch approx
Secondary - 36 inch approx
Anyway headers run to the end of the gearbox

I have not had any testing done, but the car has bags of low to mid grunt which is what I was looking for.

I feel that the only reason there is limited interest in header design on roadsters is because of the x-member.

Food for thought below

One thought I had for a standard roadster was to separate the 2 secondaries pipes and run 1 through the x-member and the other underneath, measurements show that ground clearance still should be OK, so long as your car has not been lowered to much.

Regard

Phil R

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