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#2414845 - 12/07/17 03:54 PM W2 stroker build: header primary tube size
Diplomat360 Offline
pro stock

Registered: 01/20/03
Posts: 1207
Loc: Windsor, ON, Canada
Looking for recommendations regarding the size of the header primary tube.

Intended use is (M-body in the sig, 3600 lbs race weight): weekend driver, not a drag racer, a typical street/light-strip car. W2 based 408 stroker, forged crank, H-beam rods, 10.5:1 CR, hydraulic roller cam, 6500 max RPM, 4k converter, 4.10 rear end ratio.

I am moving to the TTI headers, specifically looking at the 340W2 (1-5/8" primary) or 340W2-17835 (1-7/8" primary) setups.

Previously I have only ran 1-5/8" tubes, always on a stock displacement motor (360"), these worked well on the car. The remainder of the exhaust are dual 3" pipes with X-pipe, all feeding into Hooker MaxFlow mufflers.

Given the move to a stroker (408) and the cost of these headers in particular, I am wondering whether I should be looking at the 1-7/8" tubes in order to get some "room to grow"?

While I always aim for max-performance effort within a particular combo, this is not a motor that will spend a lot of time in the upper RPM, it simply is not a drag race vehicle.

My original thinking was to stay with the 1-5/8 tubes, but given the extra cubic inches that the stroker brings, the fact that at WOT I push the converter to the 4k stall and with the 4.10 gears it'll buzz real quick I am now wondering what the best option is. What do you recommend?
_________________________
1980 Dodge Diplomat Coupe, 360-4bbl, 727, 3.91 SG motivated sleeper! 1981 Dodge Diplomat Coupe, /6 38K mi. survivor car, awaiting restoration.

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#2414850 - 12/07/17 04:04 PM Re: W2 stroker build: header primary tube size [Re: Diplomat360]
madscientist Offline


Registered: 09/17/14
Posts: 1913
Loc: Washington
I run 1.875 tubes on a 340 CID street car.

That would be the minimum size I would run.
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Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston

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#2414869 - 12/07/17 04:40 PM Re: W2 stroker build: header primary tube size [Re: Diplomat360]
MR_P_BODY Online   content
Master

Registered: 06/13/03
Posts: 50628
Loc: Romeo MI
I would look at 1 3/4(if you can find them
or the 1 7/8) being that its a street ride
wave
_________________________

W-9 8.94 @ 151 NOW ON E-85
Mike "Raff"...(180)Watching over us
CAR IS FOR SALE

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#2414951 - 12/07/17 07:29 PM Re: W2 stroker build: header primary tube size [Re: Diplomat360]
fast68plymouth Offline
I Live Here

Registered: 01/20/03
Posts: 10705
Loc: So. Burlington, Vt.
For comparison, when I was testing my 383....... Unported 906's, rpm intake, solid cam....... Going from 1-3/4 x 3 headers up to 1-7/8 x 3 headers picked up power pretty much everywhere(within the tested range).
More tq and more hp.

I don't recall the amount off the top of my head..... Around 15hp iirc...... On a motor smaller than what you're building, and with much lesser flowing heads.

The info is in the tech archives if you're curious.
_________________________
68 Plymouth Satellite, 383, stock 906's, 3550lbs, 11.18 @ 123, 1.51 60'
WD- Comp Cams / Indy Cylinder Heads

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#2415026 - 12/07/17 09:37 PM Re: W2 stroker build: header primary tube size [Re: Diplomat360]
Diplomat360 Offline
pro stock

Registered: 01/20/03
Posts: 1207
Loc: Windsor, ON, Canada
Well, sort of late to the game with this info, but I did call TTI when I got some free time to get their recommendation. The gentlemen I spoke with literally said: "...if over 600 hp then use 1-7/8" pipe...".

Even when I asked him for the "room to grow", it all came down to that seemingly magic 600hp mark.

Alright, a bit weird I think, because as I've been scouring the net tonight trying a learn a bit more about this, I am universally seeing that 600 level being more of a 500 mark. Again, these are just numerous posts from folks like you and I.

I did come across a decent Header Ho-Down article, where 4 different sized pipes were compared. Even on a smaller displacement engine (that was a Chevy 383) it appears the big 1-7/8" primary pipes posted some impressive dyno numbers throughout the combo powerband. So seemingly counter-intuitive to the "smaller primary pipe nets more torque".

How is the clearance with the 1-7/8" header install on a SB look like?

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#2415031 - 12/07/17 10:01 PM Re: W2 stroker build: header primary tube size [Re: Diplomat360]
Bad340fish Online   content
master

Registered: 01/20/03
Posts: 5562
Loc: Tulsa OK
I have 1 7/8 TTI W2 headers on an Abody. They fit tight but they fit great. The one thing the instructions lack is they only tell you to jack the car up. They do not tell you that you need to jack the car up really really really high, but do that and they go right in.
_________________________
68 Barracuda Formula S 340

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#2415035 - 12/07/17 10:11 PM Re: W2 stroker build: header primary tube size [Re: Diplomat360]
MR_P_BODY Online   content
Master

Registered: 06/13/03
Posts: 50628
Loc: Romeo MI
With 1 7/8 you shouldnt have any problems..
you might want to run 1 7/8 but with a 3.5"
collector.. will make more torque.. I'm running
1 7/8 with a 3.5" collector on my 416... It does
go back down to a 3" after the collector but I
also run electric dumps right after the collector
to help reduce back pressure
EDIT
this is with a full exhaust out to the bumper
wave


Attachments
IMG_20140528_120446433_HDR-w640-h479.jpg




Edited by MR_P_BODY (12/07/17 10:17 PM)
_________________________

W-9 8.94 @ 151 NOW ON E-85
Mike "Raff"...(180)Watching over us
CAR IS FOR SALE

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#2415045 - 12/07/17 10:25 PM Re: W2 stroker build: header primary tube size [Re: Diplomat360]
madscientist Offline


Registered: 09/17/14
Posts: 1913
Loc: Washington
I agree on the 3.5 inch collector. I forgot to mention that.

I would also make sure you have 18 inches of collector. Maybe a bit more.
_________________________
Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston

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#2415055 - 12/07/17 10:44 PM Re: W2 stroker build: header primary tube size [Re: Diplomat360]
humpty Offline
enthusiast

Registered: 10/17/07
Posts: 353
Loc: Minnesota, USA
No doubt I'd go with the 1-7/8" primary tubes. I have the same on my W2 408 and it made good torque and hp with a 950cfm 4150 on a single plane Indy intake. I was surprised when it picked up everywhere by adding a 1050 dominator (thanks again Thump!). This combo is not set on kill but it shows they like to breath.
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72 Duster - 408ci W2, 10.18@131. Shooting for 10.0's in 2018!
https://m.youtube.com/watch?v=Q4P51j38-MI

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#2415102 - 12/08/17 01:41 AM Re: W2 stroker build: header primary tube size [Re: Diplomat360]
Cab_Burge Offline
I Win

Registered: 08/23/03
Posts: 30567
Loc: Bend,OR USA
See if TTI will make you a set of 1 7/8 to 2.0 step headers with 3.5 inch collector scope
This is to make sure you have enough pipe for real future growth devil whistling AKA go big now instead of later twocents How much does a 150 HP NOS kit cost now work grin
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Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)

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#2415112 - 12/08/17 06:30 AM Re: W2 stroker build: header primary tube size [Re: Diplomat360]
gregsdart Offline
master

Registered: 01/21/03
Posts: 8219
Loc: Frostbitefalls (Rocky&Bullwink...
Just thinking, how would step 1 3/4 to 1 7/8 work? I know 1 5/8 to 1 3/4 work very well on a 500 hp 408 build.
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GREG
Educated at SHK U
Measure with yardstick
mark with chalk
cut with torch!



528 cubic inch alky injected 440-1 wedge, 3055 race weight.
8.779 at 153.16 mph. 1.289 60 ft. density altitude 1617 feet. Best 60 ft 1.24

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#2415140 - 12/08/17 08:27 AM Re: W2 stroker build: header primary tube size [Re: Diplomat360]
babarracuda Offline
pro stock

Registered: 09/27/03
Posts: 1464
Loc: Carson City, NV
I have 410" stroker with W2 heads. I have TTI headers with 1 7/8" primary tubes. Works great for my 3100 pound Barracuda with 3.23 gears and 27.5" tires. Drove from Carson City to Las Vegas and ran 12.34. I think that it would run 12 0's at sea level. I am please with the setup.

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#2415150 - 12/08/17 08:40 AM Re: W2 stroker build: header primary tube size [Re: Diplomat360]
Guitar Jones Offline
master

Registered: 12/18/09
Posts: 9429
Loc: in a cattle trailer down by th...
I have to agree with the 1 7/8 with a 3 1/5 collector. I'm currently running a 2" tube with a 4" collector on my 408.
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W5 408 cid, 1.324, 6.155 @ 110.34, 9.756 @ 134.67. Oh yeah, it's all Mopar too, 904 trans and an 8.75 rear!!

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#2415207 - 12/08/17 10:38 AM Re: W2 stroker build: header primary tube size [Re: gregsdart]
madscientist Offline


Registered: 09/17/14
Posts: 1913
Loc: Washington
Originally Posted By gregsdart
Just thinking, how would step 1 3/4 to 1 7/8 work? I know 1 5/8 to 1 3/4 work very well on a 500 hp 408 build.



I've never seen a step header make more power than a straight header if the straight header was correct.
_________________________
Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston

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#2415211 - 12/08/17 10:41 AM Re: W2 stroker build: header primary tube size [Re: Diplomat360]
fast68plymouth Offline
I Live Here

Registered: 01/20/03
Posts: 10705
Loc: So. Burlington, Vt.
I don't feel the 3.5 collector is the right set-up for the OP's combo.

Ideally, I would want 1-3/4 > 1-7/8 stepped primaries with a 3" collector for that combo if I had the choice.

IMO, the 1-5/8 primaries and w2 heads doesn't make any sense.......well...... Maybe on a 318.
_________________________
68 Plymouth Satellite, 383, stock 906's, 3550lbs, 11.18 @ 123, 1.51 60'
WD- Comp Cams / Indy Cylinder Heads

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#2415231 - 12/08/17 11:17 AM Re: W2 stroker build: header primary tube size [Re: madscientist]
MR_P_BODY Online   content
Master

Registered: 06/13/03
Posts: 50628
Loc: Romeo MI
I have tested a 1 3/4-1 7/8 step header on my
W-9.. it made more low end torque.. then I
went to a 3 step.. 1 3/4-1 7/8- 2.00.. still
had the low end torque and better on top end..
I ended up building the 3 step
wave
_________________________

W-9 8.94 @ 151 NOW ON E-85
Mike "Raff"...(180)Watching over us
CAR IS FOR SALE

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#2415661 - 12/09/17 08:49 AM Re: W2 stroker build: header primary tube size [Re: madscientist]
1Fast340 Offline
top fuel

Registered: 02/21/07
Posts: 2453
Loc: sweden
Originally Posted By madscientist
Originally Posted By gregsdart
Just thinking, how would step 1 3/4 to 1 7/8 work? I know 1 5/8 to 1 3/4 work very well on a 500 hp 408 build.



I've never seen a step header make more power than a straight header if the straight header was correct.

Take a look at the prostock and nascar guys anytime you want,they do and pay anything to make that last fraction of a hp.

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#2415675 - 12/09/17 09:28 AM Re: W2 stroker build: header primary tube size [Re: Diplomat360]
79410aspenrt Offline
enthusiast

Registered: 08/01/11
Posts: 228
Loc: Saskatchewan (SK)
no fitment problems with 1-7/8'' TTI's. that's what i run with zero issues.

go with the 1-7/8'' and never look back
_________________________
77 Plymouth Volare RoadRunner Drag car


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#2415679 - 12/09/17 09:35 AM Re: W2 stroker build: header primary tube size [Re: Diplomat360]
340Cuda Online   content
top fuel

Registered: 04/04/03
Posts: 1885
Loc: Tulsa, Oklahoma
A long time ago the late Jere Stahl told me that headers were a 5% deal. That is from the best to the worse you are talking about 5% of your power.

I don't know how much the difference between a header that is good compared to a header that is great, but you probably are not going to help or hurt things a whole lot.

And then there is the "Engine Masters" episode where they beat the daylights out of a set of headers and have little effect.

Bill

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#2415904 - 12/09/17 06:25 PM Re: W2 stroker build: header primary tube size [Re: 340Cuda]
Streetwize Offline
master

Registered: 01/20/03
Posts: 9609
Loc: Weddington, N.C.
I don't know about primary tube but if the collector is too small (where it doesnt allow the motor to achieve it's natural torque peak RPM) it will limit top end power....(so to me) that could likely be more than 5% of the potential peak power. Stahl was also likely talking about an open header/race situation which is obviously very different from a street/strip type application. In other words the peak torque limit of a too small collector could very likely lower the HP trajectory/rate of rise/curve from that RPM all the way to peak....that being said.... (cont'd below)



Edited by Streetwize (12/09/17 07:27 PM)
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World's Quickest Diahatsu Rocky (??) 414" Stroker Small block Mopar Powered. 10.84 @ 123...and gettin' quicker!

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In Car:

https://www.youtube.com/watch?v=PjXcf95e6v0

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