El Camino project car

[GoCougs]

Headers are usually sucky - rusty, flimsy, leaky and loud (esp. under the hood, which bugs the heck out of me). On any sort of street machine the gains are in the upper RPM ranges usually come with sacrifices down low. Things have to get way beyond stock for headers to provide more power at all RPMs and you'd have to spend a boatload to even approach the durability of factory cast manifolds.

All the hi-po Chevy small blocks of the muscle car hey day (350 hp-375 hp LT-1, L79, L84, DZ302, etc.), plus the modern small block up to and including the LS7 (a 600 hp motor if built/rated in the '60s) and new LT1, all have cast exhaust manifolds from the factory. Perhaps get a pair of vintage hi-po manifolds, or, some companies are providing new hi-po modern cast iron manifolds.

[CaminoRacer]

After calling some machine shops, most are gonna take too long and/or be kinda expensive. Plus, it turns out that my dad would probably end up getting a Blueprint 383 next winter anyway, leaving his current engine to sit in the garage in perfectly good condition. So it's engine swap time.

He ordered this: http://www.blueprintengines.com/index.php/products/bp-gm-crate-engines-landing/gm-383-main/item/gm-383-engine-specs-bp38313ct1

430 hp, 450 ft-lbs.

The engine going into my car is a bit tamer. Take all of the specs for that 383 and reduce them by a 5% and you'll basically have it. I'll need to buy an air gap intake to match the cam. Hopefully my 650 cfm carb can still handle it.

[CaminoRacer]

Headers are usually sucky - rusty, flimsy, leaky and loud (esp. under the hood, which bugs the heck out of me). On any sort of street machine the gains are in the upper RPM ranges usually come with sacrifices down low. Things have to get way beyond stock for headers to provide more power at all RPMs and you'd have to spend a boatload to even approach the durability of factory cast manifolds.

All the hi-po Chevy small blocks of the muscle car hey day (350 hp-375 hp LT-1, L79, L84, DZ302, etc.), plus the modern small block up to and including the LS7 (a 600 hp motor if built/rated in the '60s) and new LT1, all have cast exhaust manifolds from the factory. Perhaps get a pair of vintage hi-po manifolds, or, some companies are providing new hi-po modern cast iron manifolds.

Correctly sized headers will provide torque and power gains throughout the whole rev range. And the more powerful the engine is, the more of a difference it makes.

http://www.superchevy.com/how-to/49178-headers-power-increase/

The comparison test pitted the stock cast-iron exhaust manifolds against a set of 1-5/8-inch Hooker headers that were plumbed into the same 2-½-inch exhaust system. As you can see from the results of Test 1 versus Test 2, the headers were an unqualified success. If all you looked at was peak horsepower, the cast-iron engine made a best 239 hp at 4,200, while the headers pumped the power up to 255 hp at a 200-rpm–higher 4,400 rpm. This alone is a significant 16 hp, but that's not all of the story. The headers not only reduce exhaust restrictions, which lowers exhaust backpressure, but the length and diameter of the header pipes also have a dramatic effect on the torque curve as well. This is perhaps a bigger story than just the horsepower increase.

Look closely at the two torque curves and you will see a spike of 53 lb-ft of torque at 3,400 rpm while the 3,200-rpm line reveals a torque increase of 26 lb-ft of torque. These are amazing numbers that average more than 26 lb-ft of torque between 3,000 and 3,800 rpm.

Next, we started with a 436hp 355 equipped with a set of Air Flow Research aluminum heads and a Comp Cams 274 Xtreme Energy camshaft with 230/236 degrees of duration at 0.050-inch tappet lift with 0.552/0.555-inch valve lift. On the induction side, we added an Edelbrock Performer RPM and a 750-cfm Holley carburetor. This engine obviously needed a very efficient exhaust system if it was going to perform well. But for Test 3, we corked it up with a pair of exhaust manifolds similar to the ones used on the mild engine test and tied them in with a pair of 2¼-inch exhaust pipes.

In this case, it's easy to guess that the stout small-block fizzled with this much restriction on the exhaust side. Test 4 revealed how much headers are worth on a well-prepared engine by pulling out an impressive 68 lb-ft of torque improvement at 5,200 rpm (338 versus 406) that is equivalent to a mild nitrous hit in terms of pure torque. Peak-horsepower improvements were actually even more impressive with a 70hp gain at 6,200 rpm. We did the math and came up with a staggering average increase of 46 lb-ft of torque. That means that throughout the entire 4,000-rpm band from 2,600 to 6,600 rpm, the engine made 46 lb-ft of torque more with the headers at every single data point.

[280Z Turbo]

False. Aftermarket parts reduce horsepower.

[GoCougs]

Correctly sized headers will provide torque and power gains throughout the whole rev range. And the more powerful the engine is, the more of a difference it makes.

http://www.superchevy.com/how-to/49178-headers-power-increase/

Note on those two engines they only speak of 3,000+ RPM, which is the last 30-50% of their RPM range. One has to look at 75%+ of the RPM range for a street motor; case in point which I've posted before:  http://www.ultimateheaders.com/dyno.shtml

Both headers lose more down low than they add up top, plus the long tube headers have a 98% chance of not fitting on a street machine (or, at least not on a Z06 or Z28). The vehicle with the LS7 manifolds will be the better street machine.

[CaminoRacer]

The average increase on the built 355 was 46 lb-ft, from 2600-6600 rpm.

SBC manifolds are in no way performance-oriented and will NOT help me go faster in autox or stop light drags. Quit yer bullshit. The only reason I contemplated it was to rid myself of the suffering that is dealing with spark plugs while the headers are installed, and installing/removing the headers themselves. Purely non-performance goals.

[280Z Turbo]

I've had no issues with spark plugs, leaks, or fitment with long tube headers on the Vette.

It's cheaper to cast a part than to fabricate it. That's why they came with cast iron exhaust manifolds. There's no magic in 50 year old exhaust manifolds.

[280Z Turbo]

Maybe Cougs likes granny shifting from 700 to 2000 rpm.

[CaminoRacer]

I've had no issues with spark plugs, leaks, or fitment with long tube headers on the Vette.

It's cheaper to cast a part than to fabricate it. That's why they came with cast iron exhaust manifolds. There's no magic in 50 year old exhaust manifolds.

My current headers came with the car, so they're probably no name cheapies. A good set of long tubes should have no leaking problems and fit nicely. However, it'll still be nearly impossible to install/remove long tubes on my driver's side without disconnecting the steering column and/or clutch linkage. That's why I'm looking at shorties.

[MX793]

I've had no issues with spark plugs, leaks, or fitment with long tube headers on the Vette.

It's cheaper to cast a part than to fabricate it. That's why they came with cast iron exhaust manifolds. There's no magic in 50 year old exhaust manifolds.

If manifolds did not provide the best power and highest efficiency, they would not be fitted from the factory.  The OEMs invest millions into powertrain development, they aren't going to leave power and efficiency on the table.  All engines are at their optimum as designed and delivered from the factory.

[MX793]

Headers are usually sucky - rusty, flimsy, leaky and loud (esp. under the hood, which bugs the heck out of me). On any sort of street machine the gains are in the upper RPM ranges usually come with sacrifices down low. Things have to get way beyond stock for headers to provide more power at all RPMs and you'd have to spend a boatload to even approach the durability of factory cast manifolds.

So why then does the new Camaro SS come fitted with these:



instead of a cast manifold?

[GoCougs]

The average increase on the built 355 was 46 lb-ft, from 2600-6600 rpm.

SBC manifolds are in no way performance-oriented and will NOT help me go faster in autox or stop light drags. Quit yer bullshit. The only reason I contemplated it was to rid myself of the suffering that is dealing with spark plugs while the headers are installed, and installing/removing the headers themselves. Purely non-performance goals.

You should know better than trying to bring the Funny Business.

First, four of those pictures are not of the engines tested (2/10, 3/10, 9/10 (lol not even an SBC), and 10/10 (BBC)).

Two, the mild 350 was tested with 2.5" exhaust and the hot 355 was tested with 2.25" exhaust system.

Three, using some sort of PC app to claim a set of headers drops your ET from 12.58 sec to 11.97 should be illegal.

Four, each exhaust/header swap needs a carb tune - though not stated that it wasn't done given the slappy nature of the article this highly likely did not happen (and carb tuning has a big effect on power).

Fifth, search for better tests (to be added of course to the test I already posted) - your criteria are: engine dyno, unbiased source, competence, no Funny Business (PM me link(s) for approval).

Sixth, on any sort of streetable motor, headers will add some up top (and plenty of tests (stock FI motors) show zero/negligible gain, 'cause they self correct A/F), but it usually comes with a cost down low (with the added "features" such as poor sealing, poor fitment, rust, etc.).

[GoCougs]

So why then does the new Camaro SS come fitted with these:



instead of a cast manifold?

That's an aftermarket piece. The new LT1 has cast manifolds from the factory (research says they're stainless however):



So does the 650 hp LT4:



So does the 662 hp GT500 - classic log style even:

[CaminoRacer]

Primary tube length determines what rpm range benefits. Longer tubes = more low end torque. Do manifolds have longer primaries than long tube headers?

[CaminoRacer]

That's an aftermarket piece. The new LT1 has cast manifolds from the factory (research says they're stainless however):


So does the 650 hp LT4:


So does the 662 hp GT500 - classic log style even:

Those look a lot more like cast shorties than the log manifolds that I'd be installing.

And Ford doesn't know how to build a decent engine so that picture is irrelevant.

[MX793]

That's an aftermarket piece. The new LT1 has cast manifolds from the factory (research says they're stainless however):

Not aftermarket.  That is the factory "tri-Y" header on the Camaro's LT-1 (and is unique to the Camaro).  That particular photo was one of the teasers GM released to the press leading up to the final unveiling.

Another official GM press image showing the 3 powertrain options for the Camaro (LT1 is up front)

[Rupert]

Maybe Cougs likes granny shifting from 700 to 2000 rpm.

He probably doesn't double clutch like he should, either.

[GoCougs]

Pics of the actual motor show it to be similar to the Corvette manifold. But even if it didn't, they're both rated at the same 455 hp.

[MX793]

Pics of the actual motor show it to be similar to the Corvette manifold. But even if it didn't, they're both rated at the same 455 hp.

That display motor is just a generic LT-1, probably a crate motor.

[GoCougs]

Check out take-out motors from wrecked 2016 Camaros on eBay - definitely cast manifolds:

http://www.ebay.com/itm/2016-LT1-CAMARO-ENGINE-WITH-2-679-MILES-practically-new-LT1-LS2-LS3-LS7-LS9-LSX-/152112383230?hash=item236a9ac4fe:g:wl4AAOSwMN9XQ6hZ&vxp=mtr

[GoCougs]

Those look a lot more like cast shorties than the log manifolds that I'd be installing.

And Ford doesn't know how to build a decent engine so that picture is irrelevant.

Ford has struggled a bit but what is in a GT500 (or LT4 or Hellcat) motor - $50MM? $100MM? Also considering noise and cost isn't really an issue on such motors, if headers helped or were otherwise a net positive, they would be on there.

[CaminoRacer]

How come engine masters competitions use long tubes?

OEM is not just worried about cost - there's also emissions, warranty, and manufacturing time. Cast parts are much easier to mass produce than headers. You should know this already.

[CaminoRacer]

If you buy me a set of manifolds, I'll install them and give you a full dyno comparison plus 0-60, 1/8, & 1/4 mile comparison. Maybe even an autox lap time comparison.

[MX793]

Check out take-out motors from wrecked 2016 Camaros on eBay - definitely cast manifolds:

http://www.ebay.com/itm/2016-LT1-CAMARO-ENGINE-WITH-2-679-MILES-practically-new-LT1-LS2-LS3-LS7-LS9-LSX-/152112383230?hash=item236a9ac4fe:g:wl4AAOSwMN9XQ6hZ&vxp=mtr

What's under that heat shield looks like what I posted above.

[FoMoJo]

Those look a lot more like cast shorties than the log manifolds that I'd be installing.

And Ford doesn't know how to build a decent engine so that picture is irrelevant.

Ford has struggled a bit but what is in a GT500 (or LT4 or Hellcat) motor - $50MM? $100MM? Also considering noise and cost isn't really an issue on such motors, if headers helped or were otherwise a net positive, they would be on there.

You guys are just talking through your derrières. 

...and that's not even scratching the surface of Ford racing over the decades.  They planted the stars and stripes on every major racing circuit throughout the globe in every series.  Take pride.

[GoCougs]

What's under that heat shield looks like what I posted above.

There are no mounting holes for the heat shield on the shorty you posted above. Also, on the pic I posed one can see those are castings underneath the heat shield, not tubes (i.e., there is a lot of material between adjacent ports, which is not the case with the shorty you posted).

[GoCougs]

You guys are just talking through your derrières. 

...and that's not even scratching the surface of Ford racing over the decades.  They planted the stars and stripes on every major racing circuit throughout the globe in every series.  Take pride.

Sure Ford has rich history of racing but it wasn't because of their motors (which is the same for most any race program), and in general, factory racing programs bear virtually zero resemblance to what they put onto the street.

[FoMoJo]

Sure Ford has rich history of racing but it wasn't because of their motors (which is the same for most any race program), and in general, factory racing programs bear virtually zero resemblance to what they put onto the street.

Perhaps just as much now, but the racing programmes were the test beds for production upgrades; at least until they stopped building proper cars in the '70s.  As for engines, yes it was because of their motors for the most part.  Although the CSB was the choice of hot-rodders, the Windsor was the choice of most manufacturers who wanted an American V8 to stick inside of their Sports cars...even koenigsegg chose Ford's modular V8 as the basis for their first and subsequent exotics...fastest car in the world for a time.

Anyways, enough of disturbing this thread with posturing...but any poke deserves at least one rebuttal.

[280Z Turbo]

Those look a lot more like cast shorties than the log manifolds that I'd be installing.

Cougs digression.

Obviously you can cast a manifold that flows as well as a header. You need more wall thickness, but you can cast just about any shape you want. This is common sense.

The issue is that 50 year old manifolds were not designed for performance applications. I know Cougs likes being a contrarian, but sometimes conventional wisdom is correct.

[CaminoRacer]

Took the transmission apart for the second time in 2 years. Last time I used paper gaskets for the tail-housing and side cover, which leaked a lot. So this time it's gonna get gooey gasket maker. I also need to get a new speedo gear housing - currently it leaks gear oil into the speedo cable so the inner seal must be worn out. It's like $10 to fix so whatevs.

Good news is that the innards still look fresh as the day it rolled off the assembly line.