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  #1  
Old Nov 10th, 19, 01:59 AM
Rets Rets is offline
 
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Default How can I improve my cars horsepower and sound?

I have a 1976 with a inline 6 engine I want to improve on the horsepower and sound what can I do to it?
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  #2  
Old Nov 10th, 19, 12:56 PM
Big Dave Big Dave is offline
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Default Re: How can I improve my cars horsepower and sound

You could replace your old 250 six with a newer Atlas six out of a Chevy light truck or a Jeep.

The DOHC fuel injected 254 cubic inch six adapts well to turbo charging. Since it is turbo charged a lot of the energy in the exhaust is transferred to the compressor so you can run straight pipes for added noise to get the sound you want. More power and noise while retaining a straight six format.

The six you have now has a 3.875" bore and a 3.53" stroke so if you had two more cylinders it would displace 328 cubes. A SBC 327 would blow it away however because the SBC breathers much better than any configuration of six cylinder head (even the Atlas which is much improved over the old 250). Power lies in the heads, always! want more power improve the heads ability to breath. This is why people who race the Chevy in line six saw two aftermarket aluminum SBC heads into pieces that are then welded back together to form a long six cylinder head with SBC ports and valves.

Cheapest solution to your problem is a SBC 350 out of a 1996-2004 Chevy pick-up converted over to a carb and a new Vortec intake manifold. You will also need a non-computer controlled HEI distributor, and a thicker (four core) radiator. Then it can be bolted in place with two new motor mounts. To complete your conversion include two glass packs for your exhaust.

Other than including nitrous there is no easy or cheap way for a Chevy in-line six to make more power. GMC offered a 502.7-cubic-inch (8.2 L); 4 9⁄16 by 5 1⁄8 inches (115.9 mm 130.2 mm) GMC inline six. It was offered starting in 1952 and ending with the 1959 model year installed in GMC 630, 660, 720, and 750 series semi trucks. This engine was as big as and as heavy as a modern Cummins diesel engine and weighed as much so it isn't really an option. GMC offered a 478 cubic inch V6 gas engine installed in pick-up trucks, but it was also as large as a BBC which will fit in your 1976 Nova (the BBC not the GMC V6).

Big Dave

Last edited by Big Dave; Nov 10th, 19 at 01:08 PM.
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Old Nov 10th, 19, 02:10 PM
Rets Rets is offline
 
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Default

So I can’t do a thing to improve it other than switching out the engine?
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Old Nov 10th, 19, 03:14 PM
Big Dave Big Dave is offline
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Default Re: How can I improve my cars horsepower and sound

Problem is with the head since the rest of the engine is a 327 in a different form that is missing two cylinders. Jaguar and BMW make a straight six that will blow away a SBC in class racing (the 259 cube XK6 Jags beat the 327 Corvette like a rug in racing), Today's BMW DOHC straight six makes 280 horsepower out of 210 cubic inches, so a straight six isn't what limits your ability to make power but the head that Chevy cast to put on top of it's six that is killing your aspirations.

The straight six was designed for low speed torque with excellent fuel economy. Since GM policy says you are allowed only one part instead of two they designed the straight six using SBC parts, but topped the motor with a cast iron (Jag and BMW use an aluminum head that shaves 70 pounds of weight from the front end) head that shares ports to reduce cost (it was going into an economy car).

The intake ports, (there are three) have a huge opening that is blocked by an equally large cast iron boss that seals the head bolt from a vacuum leak or coolant leak. This boss effectively obstructs the port preventing air to flow rapidly into the engine without separating the fuel from the air flow. The valves are small in diameter and the stock cam keeps the power band low to match the air flow potential.

An Otto cycle engine makes it's power in high RPM operation (this is why there are no Diesel powered F1 cars, and why the Brayton cycle STP Special jet turbine was made illegal), because it is all about the number of power strokes per minute.

This power is the result of burning fuel that requires air to burn it. You can pour a five gallon can of gas into your six cylinder engine, but it will die a horrible death if you do so. An engine runs on gas fumes suspended in air not liquid gas. So fuel isn't the limiting factor, but getting air in is.

This is why people run a turbo charger or NOS on their engines. Because it is the lack of air that restricts the power an engine can make.

NOS breaks down into nitrogen dioxide and oxygen when heated. That extra oxygen is what gives your engine it's boost in power (provided you also add more fuel). Any blower adds more oxygen by pumping in more air than the engine can suck in through it's heads by itself. The only difference is in how you power the blower (compressor) with most being belt driven off the crank and a turbo using the wasted energy of the heat of combustion to power the compressor (no parasitic drain on engine horsepower to drive it).

You can turbocharge your six for more power, but since you can not reuse the plumbing required later on a V8 I advise against it. You can add a Paxton style scroll compressor to your six and aside from brackets it can later be reused on a V8 application. Same for a roots style blower though you would have to fabricate your own intake manifold to mount it in addition to brackets for the drive belt (I have seen two of these locally at car shows). I mention reusing these power adders on a V8 because even with a power adder you still will be hobbled by forcing air through a restrictive L6 head; and after being beaten by many similar normally aspirated V8 powered cars you will want a V8 as well.

Good news is your car will accept a SBC or a BBC or a Ls-x engine so you can drive as fast as you can afford.

Big Dave
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Old Nov 10th, 19, 03:16 PM
62 NovaWagon 62 NovaWagon is online now
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Default Re: How can I improve my cars horsepower and sound

There's a lot you can do to improve the IL6, it's only money, lol.. First I would highly suggest you get the IL6 bible by Leo Santucci 1st and second editions, a world of info there..

https://www.abebooks.com/book-search.../leo-santucci/
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Old Nov 10th, 19, 03:24 PM
Big Dave Big Dave is offline
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Default Re: How can I improve my cars horsepower and sound

Leo has a Studebaker powered by a 292 bread truck six with a welded SBC head on top to make lots of power to win consistently in his CLASS of racing. Still won't beat a BBC powered dragster in the quarter unless the digger driver is asleep at the tree.

https://www.bing.com/images/search?v...jaxhist=0&vt=0

https://www.bing.com/images/search?v...8712495&sim=11

Big Dave
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Old Nov 10th, 19, 08:27 PM
62 NovaWagon 62 NovaWagon is online now
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Default Re: How can I improve my cars horsepower and sound

He also had this one that was a constant winnwr..

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