ive seen it said time and time again that you need an h pipe with hipo manifolds. my question is why? couldn't you run them with a straight dual exhaust? im not looking for a manifold vs headers vs whatever debate, just wanting to learn more.
why do you need an H pipe with hipo manifolds?
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The whole point of a crossover pipe(X-pipe or H-pipe) is to get the out-of-balance exhaust pulse to the other bank to prevent it causing backpressure. There are 2 ways to do this...with an H(or X) pipe or do it like the GT-40 did it....by sending primaries to the opposite header:
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To be fair, in the case of the GT40 it also had the effect of creating a clockwise(or counter-clockwise) swirl as each cylinder fires, which also reduces backpressure and makes more power.
Fun fact though: Only v8s benefit from a crossover pipe....v6s do not, since they do not have that "out-of-balance" cylinder, all adding a crossover pipe does for them is change the exhaust note.
To be fair, in the case of the GT40 it also had the effect of creating a clockwise(or counter-clockwise) swirl as each cylinder fires, which also reduces backpressure and makes more power.
Fun fact though: Only v8s benefit from a crossover pipe....v6s do not, since they do not have that "out-of-balance" cylinder, all adding a crossover pipe does for them is change the exhaust note.
A crossovers isn't required.
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Correct
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To clarify more-- regular manifold,hipo or headers ,does not matter which. Run exhaust with or without H/x pipe.
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I actually like the sound of divorced true duals the best. And no you don't have to have an H pipe but it is better to have one no matter what manifolds or headers you have. I do have an H pipe on my car. Early GT350s, AC Cobras, Corvettes and old hot rods don't have H or X pipes etc Millions of factory single exhaust cars were converted to dual exhaust back in the day and most didn't have a crossover pipe.
800 × 600
800 × 600
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I use an H pipe with headers.
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Ironic, because there's no gain from stock hipo manifolds anyway.....
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You don't NEED one but it's there for a reason. Remember, Henry didn't spend any extra when it wasn't needed.
In the illustration below, the firing order is shown outside the diagram in bold black numbers. The green line with an arrow indicates that when that cylinder is on the exhaust stroke, pushing expanding spent gases into the exhaust system, the cylinder it's pointing at is at TDC ending the exhaust stroke and entering the intake stroke (the "overlap" portion when both intake and exhaust valves may be open and "reversion" in play. Reversion is when the airflow wants to go in the opposite direction of normal due to pressure changes. The crossover is designed to "balance" the reversion effect to help the exhaust gases efficiently escape.
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Searching for dyno testing of crossover, I only see people reporting on sound. Does anyone have link showing actual HP/TQ gains?
I plan to install one to tone down the noise but I'm a little skeptical that they do anything for HP/TQ unless you have long tube headers and the crossover is placed right at the collector.
I plan to install one to tone down the noise but I'm a little skeptical that they do anything for HP/TQ unless you have long tube headers and the crossover is placed right at the collector.
The H pipe will also on getting rid of that drone that some exhaust systems have.
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Mellows the tone a little and increases torque in my experience. It should since it effectively doubles adds a pipe to each pulse…
Another aspect is that it makes the exhaust system sturdier. With two single pipes, it's quite a distance between the manifold and the hanger at the end of the floor pan. Wiggling around this long pipe due to vibrations could cause issues with exhaust sealing. That's actually something OEMs care more about that gaining a horsepower or two, especially if it also reduces noise.
It's a detail that has some benefit. Nothing spectacular but worth it.
But to answer the OP's question: I think what people meant when saying that you need an H pipe with Hipo manifolds is that you need a Hipo specific H pipe. The one for regular manifolds doesn't fit due to the different exits.
It's a detail that has some benefit. Nothing spectacular but worth it.
But to answer the OP's question: I think what people meant when saying that you need an H pipe with Hipo manifolds is that you need a Hipo specific H pipe. The one for regular manifolds doesn't fit due to the different exits.
Yes, but life is more fun if you keep believing that they do 😁
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Straight Exhaust vs H-Pipe vs X-Pipe! - Engine Masters Ep. 22 | Straight Exhaust vs H-Pipe vs X-Pipe! - Engine Masters Ep. 22 The stock 5.3L GM LS3 engine in the video used the "go to gold sauce", as David describes... | By Premium Oil Inc | Facebook
၁.၄ထောင် views, ၂၇ likes, ၃ loves, ၁ comments, ၁၀ shares, Facebook Watch Videos from Premium Oil Inc: Straight Exhaust vs H-Pipe vs X-Pipe! - Engine Masters Ep. 22 The stock 5.3L GM LS3 engine in...
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X and H are identical on power. Both make more than none.
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Engine Masters on Motortrend tested them against each other on a dyno in Episode 22. The result was 5-6 lb/ft more torque in lower RPMs for both H and X pipe over straight dual exhaust. Very minimal gains anywhere else.
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