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512 B exhaust for the street tight fit vs HP restriction #2551583
09/18/18 05:13 PM
09/18/18 05:13 PM
Joined: Jul 2007
Posts: 1,682
Philadelphia
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radar Offline OP
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radar  Offline OP
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Joined: Jul 2007
Posts: 1,682
Philadelphia
Howdy Fellas

I have my new 512 sitting in my chassis but not mounted yet. This is in a 1954 dodge pickup on an 89 2wd dakota frame. I had picked up some crusty 30 year old new old stock headers from a guy that said he never got around to putting them in his 69 charger. They are scratched up with black bbq paint over old white paint but the insides have a touch of surface rust and no exhaust soot. I’m realizing now that my motor is sitting poking through a huge hole in my firewall that these old no-name 1 7/8” long tubes are going to be a ton of work to make room for not to mention install. I’m not sure I want to do that much work for a set of headers that I can’t replace when they rust out- I can’t find any for sale that look like them. The chassis has a rack in front of the motor crossmember so that helps clearance but my firewall is cut and the rear two cyls are under the dash so it’s not a normal install. I already have a mini starter.

I have 1977 400 B motor manifolds I had originally considered my backup plan but if I can get a little more flow out of a shorty I would like to get the horses and save the weight. The manifolds must weigh fifty pounds and I’d have to hunt down all the rusted out standoff nuts and studs too.

The obvious answer is the hedman angled shorties. Unfortunately I am short a few hundred bucks- trying to stick to a budget on this build. That leaves used or home made or cheap as my options.

I ordered a set of the sanderson style stainless shorty headers off amazon- which can get returned if they don’t fit or plug access is bad or whatever. They have tiny 1 5/8” (1.625) tubes but they are super short and all dump to 3”. I figured if they flow better than manifolds I can still probably get north of 400hp to the wheels and off idle torque should be fine with all the cubes and a 2500 stall. I have an rpm intake, 750 holley, .507”/.510” lift 240°/246° 10°lsa cam installed at 105°, unported stealths, a touch rowdier than a tow truck but definitely a street build.

I planned on probably being done making power around 5000rpm so I probably don’t need super comps or 2”+ tubes with 3.5” collectors but 1.625 is a header tube for a hot 318 not a warm 512. On the other hand Andy F made good power with manifolds and similar duration but I think he had 12° or 14° lsa. If this manifold flows worse than mannys I’ll just return it.

Or if the hedmans are really going to be worth it like +50hp +75tq maybe I’ll save up the $400 for them. I’m guessing that the tiny huggers I ordered will kill 20-30hp from street long tubes? I dunno this is all guesses but if you read this far thanks and hopefully you see the compromises I’m looking at.

Any ideas or comments are welcome. Please keep in mind I won’t be racing but niether do I want a 300hp stroker big block. If it’s basically done at 4700 I can live with that on the street that’s why ma made more gears wink

Here’s the baby shorties link:
https://www.amazon.com/gp/aw/d/B01M991Q9O

Rdr

Re: 512 B exhaust for the street tight fit vs HP restriction [Re: radar] #2551588
09/18/18 05:19 PM
09/18/18 05:19 PM
Joined: Jul 2007
Posts: 1,682
Philadelphia
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radar Offline OP
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I should also say I’m only considering the small tube shorties with the knowledge that full throttle blasts will probably be the exception not the rule. It’s not going to be like wringing out a 273 where you can constantly mat the throttle and let it eat. I’m not interested in dyno numbers but I’ll be disappointed if new camaros can beat me 0-35mph! I should be at 3000lbs

Re: 512 B exhaust for the street tight fit vs HP restriction [Re: radar] #2551702
09/18/18 10:41 PM
09/18/18 10:41 PM
Joined: Jan 2003
Posts: 30,947
Oregon
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AndyF Offline
I Win
AndyF  Offline
I Win
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Posts: 30,947
Oregon
I have 485 hp to the rear tires with cast iron manifolds. My combo is 512 inches, 246 hyd roller cam and pump gas compression. Not sure why your combo should be much different. My heads are ported so that might be a difference but otherwise you should be in the same ballpark.

https://youtu.be/xG3-_YJGdZ8

Next time I pull the engine out I'll probably switch over to the Schumacher tri y headers just to get rid of the way the exhaust manifolds hang over the valve covers. I don't like all the heat from the manifolds cooking the valve cover gaskets and the master cylinder. But I'm not looking for any more performance. The car makes more power than I need on the street as it is.

Re: 512 B exhaust for the street tight fit vs HP restriction [Re: radar] #2552032
09/19/18 07:03 PM
09/19/18 07:03 PM
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
Mr.Yuck Offline
Not enough dumb comments...yet
Mr.Yuck  Offline
Not enough dumb comments...yet

Joined: Jan 2003
Posts: 24,562
Brookeville, Md
long shot here...what about A-body fender wells?


[IMG]http://i66.tinypic.com/pui5j.jpg[/IMG]
Coming soon!!!!
Re: 512 B exhaust for the street tight fit vs HP restriction [Re: radar] #2552207
09/20/18 05:51 AM
09/20/18 05:51 AM
Joined: Jul 2007
Posts: 1,682
Philadelphia
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radar Offline OP
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Philadelphia
Thank you both for the responses!

Mr Yuck I have been looking at them for sure. The problem is that the motor is buried in the firewall. #7 & #8 cylinders are basically under the dash. I I think the A body ones would cut into brake booster land (if I can even fit power brakes!) Custom fenderwell headers would be cool if I ever wanted to chase ETs or got used to the power. I am trying to only cut a motor sized hole plus room to go up over drop in spool mounts and hopefully get wrenches in for spark plugs header bolts and be able to pull the valve covers. I’m also considering a removable firewall section sort of like a van but way less drastic. That will happen after plumbing and fire up anyway.

It looks like center dumps might be the ticket. I’ll find out on monday when the big brown truck comes. If they fit well I’m hoping to go 3” off the collectors, down and then mandrel bent 90° under the floor then tapering up to a rediculous 3.5” exhaust with dual flowmasters and an h pipe that I got used for pennies. I also got some 3.5” turn downs that will either aim at the ground in front of the axle or shoot diagonal at the tires for the occasional impressive billowing burnout.

Here’s a link I put a pic on imgur
https://imgur.com/gallery/nazeTNf

Or if that link doesn’t work here’s my pic heavy build thread- link should go to the last page and motor mockup is on the bottom.
http://p15-d24.com/topic/47345-512-cid-c-series-on-dakota-chassis-build-thread/?page=4

I think it will sound cool almost no matter what I do but Andy you got my hopes up I won’t be choking all the power out of this thing.

Re: 512 B exhaust for the street tight fit vs HP restriction [Re: radar] #2552428
09/20/18 06:20 PM
09/20/18 06:20 PM
Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY Offline
Master
MR_P_BODY  Offline
Master

Joined: Jun 2003
Posts: 52,972
Romeo MI
Why dont you move the engine forward so its
not stuck in the firewall.. your just in the
beginning stages of the work.. do you know how
to weld and do you have a welder.. I have a
small block in a Rampage and if you measure the
length of the engine itself you will see that
the BB is shorter than a SB from the back to the
front with out the pump and fan.. you can put
a remote pump on it and if needed put the rad
in front of the yoke.. dont get stuck putting
your engine in a hole.. I played that game once
on my 38 Ply.. it makes for lots of problems
wave

Last edited by MR_P_BODY; 09/20/18 06:23 PM.
Re: 512 B exhaust for the street tight fit vs HP restriction [Re: radar] #2552494
09/20/18 08:40 PM
09/20/18 08:40 PM
Joined: Jul 2007
Posts: 1,682
Philadelphia
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radar Offline OP
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radar  Offline OP
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Philadelphia
Mr P- The radiator is already mounted very nicely with tig welded aluminum brackets and an hhr fan. I had always planned on some motor setback. I know it’s not going to put a ton more weight on the rear but I kind of always wanted to do one. Might be my last? Plus the stock firewall was a mess (not anymore now it’s a hole!)

The cheapo stainless shorty headers showed up 4 days early today wow. 3/8” flanges and it doesn’t look like my straight plugs will be a problem, boots either. They look like they will be way less headache and the welding on them is not bad at all. Only surprise is they come with angled downpipe stubs but the collector is 3” and the stubs neck down to 2.5 right away! Scrap! I’ll have to weld up some new ones to get the angle right. $100 well spent!

Re: 512 B exhaust for the street tight fit vs HP restriction [Re: radar] #2553546
09/23/18 10:47 AM
09/23/18 10:47 AM
Joined: Jan 2005
Posts: 4,369
Michigan
MarkZ Offline
Worthy
MarkZ  Offline
Worthy

Joined: Jan 2005
Posts: 4,369
Michigan
Originally Posted By radar
The cheapo stainless shorty headers showed up 4 days early today wow. 3/8” flanges and it doesn’t look like my straight plugs will be a problem, boots either. They look like they will be way less headache and the welding on them is not bad at all. Only surprise is they come with angled downpipe stubs but the collector is 3” and the stubs neck down to 2.5 right away! Scrap! I’ll have to weld up some new ones to get the angle right. $100 well spent!


They weren't Manzo, or something goofy like that were they? I bought a pair with hopes they would fit my Fifth Avenue doing a big block swap last year.

They weren't bad, but check them over. The biggest issue I saw was the cutouts in the flange are much bigger than standard exhaust ports. On the Edelbrock heads I had I was worried about there being enough sealing surface to keep the gaskets from burning through. Also, the flange itself is mild steel.

I have a 400 based stroker, so I don't know if this last bit applies to you. There is a protrusion on the block that prevents the header on one of the sides from sitting flush. It hits the collector. Lopping it off the block solves the issue.

In the end I didn't run them though as they didn't fit in the car. Ended up cutting them up and using the parts to fab up a set stainless headers for the car.

20170307_082622.jpg20170307_082648.jpg

1987 Fifth Avenue - 512/518/D60






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