I plan on running trueduals off edelbrock victor headers with the 3.5" collector. I plan on running some 3.5" pipes into a pair of 3.5" borla mufflers dumped under the car.

Am I gonna lose any hp without the xpipe? 2 3.5" pipes should be enough right?

 

Ok you'll get loads of people telling you will loose HP if you don't. This IS NOT 100% true.

Do you need to run a X or H pipe - No.

Is it recommended that you do - Yes.

Why?

Because a mid pipe will do potentially two things.

1. It will lower the db noise level produced by the system. This is a good thing.

2. You may see a gain with a mid pipe. Check the sticky out about mods/exhausts it has some good info from David Vizard.

Basically they tested a load of setups, 50% of the time there was NO change in BHP, the other 50% saw an increase.

So you certainly won't loose anything by adding one, and with the fact it will reduce the db output I see no reason not to run one. If you pick up a few more horses on the way, then great.

As a rule of thumb it is generally accepted that the H pipe will sound deeper and produce better low end grunt, while the X pipe will sound more exotic and make better high rpm power. Either way it will likely be pretty even between them.

There's several good companies out there, Magnaflow make a nice X pipe. Stick to 2.5" tubing unless you are planning on 550-600bhp then 3" will be a benefit.

 

I plan on running nitrous so the I dont think the 3.5" pipes will be overkill.

The reason I dont want to run a xpipe is to save money.

 

Yeah if you are spraying on a split pattern you are gonna want that exhaust side as free as possible without sacrificing the velocity.

 

it helps overall

 

Im not trying to be a punk or anything , but when you say "BHP" is that like a metric way to measure horsepower? I just wasnt sure because like you said...you are in England, and you do have an LS1.

I was just under the impression that there was rear wheel and flywheel.

 

BHP means brake horsepower. How much power they measure off a dyno brake or something.

Anyways, if I got money leftover I might do it with the xpipe for sound.

 

lol, it does seem to be an American thing not to understand BHP. Not a dig, but an observation as I have had this discussion twice this week already.

HP or Horse Power is basically the measure. It is an imperial unit, and originated by a horse pulling X weight over Y distance and time. James Watt invented the system to rate his steam engines with. So a 6hp engine would do the work of 6 horses.

There are many types of horse power, some are a measurement and some a calculation. But HOW they are derived is important.

To find out the horse power of an engine we use a 'brake' device, hence the B as this denominates the type of horse power we are referring to.

BHP is a calculated measurement, this is done by measuring torque.

HP = torque (lb ft) x rpm / 5252

So, to mearly state you car has HP is actually very inaccurate. As dyno's, engine and chassis such as Mustang and Dynojet are all BRAKE devices.

Once you have derived the BHP yes you can indicate WHERE the measurement was taken.

Most common is the flywheel, but usually this is not stated on it's own but it IS noted, I'll explain in a bit.

But you could also derive BHP at the propshaft (many boats are), the wheel hubs (such as chassis dyno's like a Rototest Dyno) or indeed at the driven wheels themself.

Thus for the sake of correctness rwhp, should really be rwbhp.

rw = rear wheels, the WHERE
b = brake the type and the HOW
hp = the unit

Now the reason you don't see manufactures claim fwbhp (flywheel), is because they also state SAE Net.

SAE Net is a standard dictated by the Society of Automotive Engineers. This dictates exactly HOW and WHERE the reading should be taken, it also covers such things as engine ancilliary devices, fuel grade, astmospheric conditions and so on.

SAE Net is ALWAYS measured at the flywheel.

So remember, when referring to HP in terms of automotive use, it should ALWAYS be BHP, then any addtions you wish to add, to denominate where the measurement was derived.

As I said there are many types of HP:

ihp - this is indicated HP, and was commonly used in the 19 Century. It is a calculation using cylinder pressure of steam engines. This will give a very different number to that of BHP, yet it is still HP

dbhp - drawbar horsepower. This is for trains as a rule. This is a MEASURED as opposed to a CALCULATED like BHP is. Basically a train pulls a special carriage which meausres the amount of pull. I think this would be intersting for cars to be measured by.

RAC HP - This was used in Britiain in the early 20th Century, it is calculated by measuring the internal dimensions of the engine and certain assumptions of efficency. I think following this logic a ZR1 Corvette would only produce ~120RAC HP

There are also many other types as well. Plus there are metric equiverlents too. A metirc HP is still a horse lifting X weight over Y distance and time. But it uses metres and KG, instead of feet and pounds.

1 Metric HP is slightly smaller than 1 Imperial HP.

Metric HP may still be listed as HP or commonly as PS.

Bascially it all gets rather confusing, and there really is nothing else quite like it.

The closest comparison I can think of is money.

What is $1.00?

Well it would depend on the type of dollar, as Australian, Canadian and American dollars all have different monetary values.

$1.00US has a different value and thus spending power to $1.00Aus eventhough they are both the same physical number.

 

Wow. I learned alot from that actually! Thanks!
this should be stickified somewhere on here!

 

Just an observation, but this is why when you look at a dyno chart the Torque and the HP lines always intersect at 5252 Rpms. The torque was measured, and the HP has been calculated.

 

yep bang on.

 

man i put 348rwhp and 355rwtq with just macs a lid and duals without an x pipe dumped before the rear. the exhaust is pretty loud but i dont mind.

 

Does it sound way better than ypipe? The car is just a weekend toy. I can deal with loud. I just want a decent sound.

 

I big overall are the 3.5" Borlas you're talking about? I've done many 3.5" systems with bullets and Twisters, but they're not too big.

 

With a PROPERLY designed exhaust system with a proper x-crossover. The exhaust will make more power due to velocity than an exhaust with no crossover. Plus it sounds better and equals out the pressure.

 

before i went put the headers and duals on the only exhaust mod on the car was an open plate borla. when i put the borla on i thought it was the best sound in the world but i was wrong.
when i first cranked up my car after installing the mac duals with 3" pipe man all i could do is grin. even the folks that say it is to loud still think it sounds awesome. i still have not had any complaints from the local magistrates, guess since so many imports are piping they dont mind a little muscle. just when i thought the piping could not get any better i decided to install a 222 cam on a 112. now it has a drag car sound to it.
as far as a x pipe putting more power down i have read that it supposed to but how much more is another question. i did not fab the system up myself i bought the headers off of big mike, this is what he had on his car when he set the 1/4 record for a stock 346 bottom end.

 

Just run headers, then extensions, then mufflers, then dumps. It is proven to work just as well, if not better than a X or H pipe. I got rid of my duals and X pipe, and am running stepped headers, mufflers, then dumps. No X or H. JMO

 

Not so, 300bhp! A typical engine dyno and some chassis dynos are brakes, but a Dynojet and some others are inertia dynos, and they measure horsepower directly: The rate at which the engine does the work of accelerating the heavy roller, and by knowing the RPM, calculate torque. (so you can measure HP on a Dynojet without any RPM input whatsoever!)

BTW, the "5252" comes from the fact that one horsepower was defined by Watt as the observed day-long capability of the average horse to raise 300 pounds a distance of 110 feet in one minute, or "33,000 pound-feet per minute". Since an engine's torque is measured on a brake dynamometer as the force applied to an arm of specified length, the 'work' done is applying that force over the distance of one revolution at the arm's radius, thus it's circumference. So HP = (Torque x 2 x Pi x RPM)/33,000 or (Torque x RPM)/5252.1.
Now what was this thread originally about?

 

How much did the sound change when you got rid of the X pipe? Louder I would guess? Maybe a little deeper?

 

For me, nothing sounds better than true duals through big pipes. The X pipe systems I've heard seem to have a higher pitch to them that I don't care for personally. It's all a matter of taste. Your setup will probably be spongy down low when cruising around but ought to be great for the juice at WOT.