Kevin91Z

iTrader: (1)

Straight from Horsepower TV:

http://www.powerblocktv.com/episodes...rformance-mods

The dyno comparison on a ZZ4 engine is right at the beginning of the episode.

A 5 horsepower and 8 torque difference on the engine dyno. I'm going to stick with my Dyno Don's 1 3/4" shorties as I like my ground clearance.

Guest

LTs > all

TA

iTrader: (1)

You have to look at the exhaust as an entire system. When you compare the third gen platform to previous and even later F bodies, our under car structure just does not lend itself to a good exhaust system on long tubes, because the car was not designed for the exhaust to exit that way. I had long tubes, and it was the resultant attempt to package two cat converters and get the pipes past the transmission crossmember and still have acceptable ground clearance with 2" head pipes. I had to mash and weld both the headpipes and the crossmember.

Going from that to the 1 3/4 shorties gave me room to run larger head pipes with no crushing or right angle bends. So with the shorties, my HP/TQ rose substantially because it allows a better SYSTEM on OUR CHASSIS. All of the high HP Thirdgens I have seen all have shorties. If you are only running open headers, you might be better w/ long tubes, but the long tube designs for our chassis is still compromised by our lack of under chassis room.

TA

Guest

[ (Non-junk/Best gains) LTs 1 3/4" - 3" > Dyno Don's]

[ (junk,low gains) hk 2055 > (bigger junk) "everything else..."]

InfernalVortex

iTrader: (4)

Facts:

1. Long tubes make more power and more torque.
2. Long tubes are impractical without extra effort.

The question "Are long tubes worth it?" is an entirely different issue and depends on the situation. If you can do it without sacrificing ground clearance (pretty easy if you can build a custom crossmember) and keeping the cat(s) in the stock location isnt a concern, then why not? It's a bolt on 5hp-10tq all the way across the RPM range improvement over shorties with the same size primaries. How many hp do you think shorties really pick up over manifolds? Maybe 10? 15? 20hp? Assuming shorties and a y-pipe net 20hp, an extra 5 is still another 25 percent improvement over that. Not to mention for our cars there's not much of a price difference between a LT setup and a shorty+y-pipe setup when comparing apples to apples. If you say a car makes 300 hp and switching to shorties + y-pipe only gets you to 320... That's still only a 3.3 percent power increase. Im not sure exactly how much power you get from switching to manifolds to good shorties, but it has been proven that going to long tubes gets you MORE for the same money.

Does that mean I recommend long tubes toe veryone? No, I generally discourage it, because having to smash and flatten pipes and have 2 inches of ground clearance when your car rides at stock height isnt fun or cool or anything worth dealing with at all, ever. But that doesnt mean long tubes are a bad idea. They're a bad idea if you're trying to work around the factory crossmember.

There are ways around this.

My car:


Not my car, and using factory manifolds, but it's the same basic idea that proves it can be done with a 700r4:

Guest

I actually just did (*in the middle of*) doing a HK 2055 to LT swap. For -LESS- than the price of Don's.

-no motor jacking (tired stock mounts) and I have decent ground clearance, Hotchkiss 1" front drop springs.

(coated LTs-used, everything else new)

Guest

Kevin91Z

iTrader: (1)

I probably didnt give enough information for people who dont know my stance on headers. Yes I know long tubes will make more power on an SBC or BBC engine. My point is, at our street-driven horsepower levels, the ground clearance and fabrication issues of long tubes are not worth the hassle in my opinion. I can get similar power levels with a good set of shorty headers and keep the exhaust tucked up in the stock location. If I was building a race car, or a car that is infrequently driven, and I wanted maximum power, then yes, long tubes are the way to go. I see header opinions given here on this forum, that long tubes are the only option and everything else is junk, and I disagree. Not everyone has the option of using long tubes, and not everyone wants the extra headache and hassle of fabricating the rest of the exhaust system to match them. For those people, shorties are the way to go. And if you go with shorties, you wont be giving up as much horsepower and torque as the "long tubes only" people say you will. Just my 2 cents.

InfernalVortex

iTrader: (4)

I had a friend who could do a lot of the fab work for me, and with my particular setup I have less invested in my headers + exhaust + labor than just a set of dyno dons headers by themselves. Dyno dons might still make a little more power since my headers are 1 5/8s primaries... but as crazy as it sounds my selection of long tubes was more for cost reasons than anything else.

The unfortunate part is when I first got them, I had a 700r4 and a dual 3 inch setup under the factory crossmember. It was awful for ground clearance and I was never able to lower the car.... did sound pretty cool though. I got tired of that and fortunately a T56 swap fell in my lap during a time when I had the car in hovercraft mode for about a year. When I got it back on the road I got one of those Skulte double hump crossmembers and had my buddy build me a new system the way it is now.

Ive seen the best and worst of long tubes, trust me. And I think a lot of it is jealous people on both sides who argue more from emotional standpoints than anything else. I dont think either side is really missing out on a bunch, but I think people need to really think about the benefits and tradeoffs of running shorties and long tubes and really understand what is involved. Long tubes can be done properly, even cheaply, but you can not treat them like a bolt on mod. They require planning and thought to pull off. 5 extra hp and a little more torque is not worth being afraid of speed bumps at stock ride height.

This is the picture I like to show guys to talk them out of long tubes...



I dont discourage everyone from doing it... because tehy can be an excellent option in the right circumstances, but they're not for everyone.

Guest

TRUTH-
Only for THEE MOST 3rd of genners, who in turn will rise to the top.



Also does any know that muffle-x's y pipe is all slip joint stuff now. I have it and it looks like itll be a wrap up deal 9no fabb). They even include good clamps for you to use your impact the tighten the Y all together and your sawzall does the rest of the exhaust.

Guest

Not -my- pics but this is the 1 I wanted to use.

TA

iTrader: (1)

Yup, they all look very familiar. I made my own "double hump" trans crossmember, but I also needed dual cats, so I had to package them in there, too.

Just look at how much lower the bottom of the long tubes and the collectors are than the subframe rails (where the jackstands are sitting). Imagine everything sticking down below those frame rails gets smashed flat on a regular basis, especially on a GTA that is lower than the standard ride height on other third gens. That is with 2" head pipes. I also think the owner of this car will regret that super tall trans pan if he drives this car on the street.

The way long tubes work is that given ideal primary tube diameter/length and collector diameter/length, the header can be tuned to scavenge very strongly at a target RPM, where peak power is reached, increasing peak power. When the primaries are substantially different lengths, it waters down the spike at peak and just spreads the power out over the rpm range. On shorties, this is even more pronounced. What you loose in peak power, you gain in a stronger/wider power band. Having been present at a LOT of dyno tests, long tubes CAN give you more power at peak, but loose power elsewhere, or long tubes that are a major compromise because of packaging concerns can loose you power everywhere, especially if they are tuned for a different RPM than the rest of the engine. When you put 2.5"(up from 2.0") sized headpipes onto the shorties, it is not uncommon to see better peak power with the shorties, as well as a wider RPM band. Even with the 2.0" headpipes on my long tubes, both the headers and the headpipes were flattened by about 1/4 of their original diameter.

This will be my 4th exhaust incarnation, and each time I learn. The most important thing is that you cannot assume "this or that" will give you more power without knowing all the variables and where in the RPM band the entire system is tuned to produce max power at.

Guest

Finally wrapped up my Long Tube swap. Mini starter was defly needed.No motor jacking, tired stock mounts, mufflex Y-pipe, no fabbing.

TA

iTrader: (1)

Which long tubes did you use? Can you post photos?

Thanks
TA

Orr89RocZ

iTrader: (20)

Headers are over rated. Turbo manifolds > *

For any given engine combo there is a proper tuned length and diameter for the "header". Whatever that length ends up being will determine if its short or long or midlength. Then it comes down to can you build it without excessive bends inside the chassis? In most cases no it cant be done. So thats where the compromise is. Some longtubes with all kind of bent tubes to fit a chassis may not work as well as a shorty with better designed primary routing.
Collector design for scavenging will really make or break the design and that only works when cam events are timed perfectly. You could overscavenge if not right and hurt power. Its all a system

Kevin91Z

iTrader: (1)

So its your opinion that long tubes are the only headers worth using, and everything else is trash? I respect your opinion, but I disagree.

Shorties have their place, as I mentioned.

TA

iTrader: (1)

You are mostly right, but for the wrong reasons. For any given combo, you can tune the headers for peak power at different RPMs by varying headpipe diameter and length, or use "mismatched" headpipe lengths for a wider powerband instead of concentrating your best scavenging all at peak for max power but a narrow power band, frequently resulting in a slower car with traction problems. You are totally correct that there is one design that will give you the highest peak numbers with your combo, but peak numbers alone are worshipping a false god, power under the curve is the best way to tune, which requires a different design header, and this all goes out the window anyway when you are trying to design headers to fit a certain chassis, especially with A/C, etc.

Also, a bend that does not change cross section makes very little difference in header performance/tuning, it is the length/diameter that matters, but it is not practical to get equal length long tubes in most chassis regardless of how many bends you use. You are 100% right regarding collector size/length, this is also critical in tuning and where your scavenging "hits" best, but all of this is academic for a street car, especially when your super-duper headers exit where you can't put a decent diameter exhaust system on them, you've just lost far more power than you gained by putting long tubes on it in the first place. It cost me a lot of time and money to figure this out the hard way.

TA

Orr89RocZ

iTrader: (20)

I wouldnt say the wrong reasons, as you have one head runner size, one intake runner size and length, and one cam shaft profile. These are all tuned for one desired rpm point. Therefore having exhaust tuned to different rpm points is being counter productive and costing power. A well designed combo doesnt just make peak numbers, it will have a fairly broad curve.

If variable cam technology is involved along with variable runner geometry, then having variable exhaust geometry would naturally go along with that. But to my knowledge that does not exist.

I have to disagree here. A bend is a much greater flow restriction than straight pipe. Proper design would have a large radius curve, or a bend of much larger csa to make up for the losses. Headers with immmediate bends off the ports are a big no no. You want to straighten flow out off the port for several inches before going into your bends. Its all about minimizing flow loss through the pipe. Flow around a bend induces velocity gradients and that can create flow separation and turbulence which restricts flow in general.

All these design requirements however are not practical or feasible in most chassis as you say. I agree there. So the compromises are made and thus brings the shorty closer to longtube performance.

Guest

The -ONLY- shortie (as I have mentioned...) that is NOT junk is DON's. Only because they have a 1 3/4" prairie, are made nice and look good.
They Y pipe from what I remember is pretty good.
Like I said...LTs will test a mans man hood, true grit and what hes made of.

Plus you've never heard (my tweaked ) L98 + LTs + straight Y-pipe.

A used set of Doug's (HK-2210 knock off)

2 POOR quality pics from the top.
-collector pics later on today
--you'll have to excuse "the mess"...

Guest

DRV S

Heated o2 $23 on ebay: http://www.ebay.com/itm/171011738304...84.m1423.l2649

PASS S




(Center Y not installed)

Reid Fleming

iTrader: (2)

For those that didn't see the video, the peak differences are:

328 hp / 372 tq (short)
330 hp / 376 tq (long)

2 HP improvement. Or a 0.6% increase in horsepower. Totally not worth the hassle of long tubes. Now I know you're going to say "but it's the area above the short tube over the whole RPM that counts."......But even that isn't that much difference.

You'd probably gain more by doing the TB bypass mod than you would by switching from short tube to long tube.

Now on something like a C5 Corvette, where you a) have room for long tubes and b) have long tubes that run half the length of the car, I'd recommend long tubes for everybody. But for 3rd gen F-bodies, nope.

Guest

Just the sound that Long tubes and straight pipes is power full to raise some muscle from the dead

skinny z

With all of this debate over long tubes vs short, it seems that the fact that the secondaries in a header design have greater sway over the power output than the primaries has been lost.
Because of the design of our V8s, they are largely insensitive to changes in primary length. This has to do with the exhaust pulses and how they arrive at the collector. In a well designed system, the exhaust can scavenge a cylinder effectively over a 4000 rpm band width. There's plenty of support and testing to show that differences as much as a foot will have little effect on power output. (Hence putting to bed the notion of equal length primaries being the be all and end all of header design)
Remember we're talking about street cars here. Not racing engines.
Secondary length and diameter can have much more effect on the power curve than the secondary.
What would have been interesting is the video not only testing the different header designs but working on the collector for each to see where the optimum might be. I can guarantee that an easy 10% increase in power would be seen in either design if the secondary was sized appropriately.

VincentZ28

iTrader: (2)

Theres a good chance that the test was done with the shorties being 1 5/8in and the longtubes were 1 3/4in.

GenX'Motorsport

^ My thoughts exactly.

88FormulaF_Bomb

iTrader: (1)

I'm not sure I trust a mechanic with hands that clean



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