W2 stroker build: header primary tube size
#2414845
12/07/17 06:54 PM
12/07/17 06:54 PM
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Joined: Jan 2003
Posts: 1,767 Windsor, ON, Canada
Diplomat360
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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?
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Re: W2 stroker build: header primary tube size
[Re: Diplomat360]
#2414850
12/07/17 07:04 PM
12/07/17 07:04 PM
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Joined: Sep 2014
Posts: 4,457 Washington
madscientist
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I run 1.875 tubes on a 340 CID street car.
That would be the minimum size I would run.
Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
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Re: W2 stroker build: header primary tube size
[Re: Diplomat360]
#2414951
12/07/17 10:29 PM
12/07/17 10:29 PM
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Joined: Jan 2003
Posts: 14,514 So. Burlington, Vt.
fast68plymouth
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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 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: W2 stroker build: header primary tube size
[Re: Diplomat360]
#2415026
12/08/17 12:37 AM
12/08/17 12:37 AM
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Joined: Jan 2003
Posts: 1,767 Windsor, ON, Canada
Diplomat360
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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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Re: W2 stroker build: header primary tube size
[Re: Diplomat360]
#2415031
12/08/17 01:01 AM
12/08/17 01:01 AM
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Joined: Jan 2003
Posts: 8,035 Tulsa OK
Bad340fish
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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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Re: W2 stroker build: header primary tube size
[Re: Diplomat360]
#2415035
12/08/17 01:11 AM
12/08/17 01:11 AM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
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Romeo MI
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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
Last edited by MR_P_BODY; 12/08/17 01:17 AM.
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Re: W2 stroker build: header primary tube size
[Re: Diplomat360]
#2415045
12/08/17 01:25 AM
12/08/17 01:25 AM
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Joined: Sep 2014
Posts: 4,457 Washington
madscientist
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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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Re: W2 stroker build: header primary tube size
[Re: Diplomat360]
#2415150
12/08/17 11:40 AM
12/08/17 11:40 AM
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Joined: Dec 2009
Posts: 20,668 in a cattle trailer down by th...
Guitar Jones
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Paddle faster! I hear banjo music!
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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.
"Follow me the wise man said, but he walked behind"
'92 D250 Club Cab CTD, 47RH conversion, pump tweaks, injectors, rear disc and hydroboost conversion. '74 W200 Crew Cab 360, NV4500, D44, D60 and NP205 divorced transfer case. Rear disc and hydroboost conversion. 2019 1500 Long Horn Crew Cab 4WD, 5.7 Hemi.
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Re: W2 stroker build: header primary tube size
[Re: gregsdart]
#2415207
12/08/17 01:38 PM
12/08/17 01:38 PM
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Joined: Sep 2014
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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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Re: W2 stroker build: header primary tube size
[Re: Diplomat360]
#2415211
12/08/17 01:41 PM
12/08/17 01:41 PM
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Joined: Jan 2003
Posts: 14,514 So. Burlington, Vt.
fast68plymouth
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I Live Here
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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 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: W2 stroker build: header primary tube size
[Re: madscientist]
#2415231
12/08/17 02:17 PM
12/08/17 02:17 PM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
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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
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Re: W2 stroker build: header primary tube size
[Re: madscientist]
#2415661
12/09/17 11:49 AM
12/09/17 11:49 AM
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Joined: Feb 2007
Posts: 2,578 sweden
1Fast340
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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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Re: W2 stroker build: header primary tube size
[Re: Diplomat360]
#2415675
12/09/17 12:28 PM
12/09/17 12:28 PM
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Joined: Aug 2011
Posts: 251 Saskatchewan (SK)
79410aspenrt
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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
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Re: W2 stroker build: header primary tube size
[Re: 340Cuda]
#2415904
12/09/17 09:25 PM
12/09/17 09:25 PM
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Joined: Jan 2003
Posts: 9,892 Weddington, N.C.
Streetwize
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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)
Last edited by Streetwize; 12/09/17 10:27 PM.
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