I just read this in the April 2008 issue of Chevy High Performance. They took a '70 Chevelle SS with a 9.0:1 compression 350 engine, rated at 250 HP and 345 TQ with 2.5" dual exhaust. It dynoed at 212 HP and 282 TQ at the wheels before the headers. Then they installed Doug's Headers 1 5/8" longtubes and gained only 11 HP and 13 TQ, to 223 HP and 295 TQ at the wheels. When I installed SLP 1 5/8" shorties on my stockish 350 engine 7 years ago, I gained about 8 HP and 10 TQ at the wheels, up to 211 HP and 290 TQ. That 3 HP and 3 TQ hardly seems worth all the hassles of trying to put long tubes into a thirdgen's cramped undercarriage. Remove 10-20 lbs of weight and you'd accomplish the same thing.

Discuss.

 

If they had done the same thing with a ZZ4 instead of that Goodwrench truck fleet replacement engine, the results would have been quite different.

 

On a mild stock motor like that, the gains are not going to be as pronounced since the motor doesnt necessarily need alot of exhaust flow since there isnt alot of intake flow going on. Its only making 220whp.

Now with a hotter motor combo, longtubes help scavenge exhaust gases out of the chamber better than short tubes. Its all in how the V8 fires its cylinders and the exhaust pulses that are seen by the header/collector.

http://headerdesign.com/extras/design.asp

good article explaining some things. The exhaust pulses cause pressure differences/waves and help create the scavenging effect. when the pressure wave hits the collector it reflects back creating the scavenging/suction wave. its a high pressure to low pressure type flow of gas basically. There are alot of tests showing the effectiveness of longer header tubes over shorter header tubes.

Results of these tests show typical V8's like a header tube length of 24-36 inches. Slightly shorter 24-30 inch lengths favor the upper rpm power while the longer 30-36" tubes favor lower rpm power.

I had a dyno graph showing some results of different primary tube lengths and the power generated by them. I cant find it at this time tho. It did show the differences between 24-36 inch lengths was marginal BUT did show shorter lengths hurt power/torque

 

I think a better frame of reference is the LS1 motor. Shorty headers help out some with an already decent factory exhaust manifold. However by adding longtube headers the power increase is quite abit more.

Kevin I bet with your car and a "tuned" long tube header setup you would see an easy 30 horsepower increase. You would be getting tantalizingly close to the magic 400rwhp number.

 

what they need to do is make a good set of 1 3/4 inch MIDlengths for these cars... a good compromise between shorties and long tubes. still retain stock y pipe location and get longer tubes for better power and increased ground clearance over longtubes

 

what they need to do is make a good set of 1 3/4 inch MIDlengths for these cars...

Actually I'm exploring the posibillity of mid-length headers with 21 inch primary pipes. That is the shortest recommended by Pipe Max for my car. The problem as it turns out would be the header on the passenger side if one were to retain the stock cat locations. Also with a tubular k-member.

 

Here is a quote from another board that did not get the "collector length" correct.

"We faced this same question last weekend while working with Pipemax on a fresh 383sbc.
The truck currently has a set of 'turbo style' mufflers that force the exhaust to make three passes inside before exiting.
For tuned length purposes we estimated the effective distance inside these mufflers, included it in our total exhaust/collector length, and then made a couple of short pipe extensions to get to the next harmonic length.
The result? We clearly screwed up the length estimation for the muffler component
The truck lost a significant amount of throttle response and 'seat of the pants' hp- it simply didn't pull as hard or as effortlessly. The exhaust note was terrible as well. All from bolting on a couple of short lengths of pipe.
While we went the wrong way in our quest, it would appear that our [wrong length] extensions supported a tuned length theory, as we were clearly now in Pipemaxs' 'worst length for hp/torque'.
Removing the extensions, put the trucks' performance back to where it was, and restored the original A/F ratios too. The wide band showed they had leaned out across the board- more reversion/dilution?
Next step is to get a decent set of Dynomax bullet style mufflers and try again."

Further along in the same post:

Quote:
i've seen that happen also....it will still act like only "external length"
and not the "internal length"..pretty weird


Weird? Agreed! Makes me feel a little better about our 'screw up'.

Quote:
What's your "current" total exhaust system length/diameters
when it was the best TQ and HP ??
how is it comparing to PipeMax ??
which Harmonic Number is it corresponding closest to ??


Using Pipemaxs' 'Short Header and Muffler' our engine should need:
1.6 inch primary 16-19 inches long, and
2.6 inch pipe with collector/total exhaust lengths of 9.7, 19.4, 38.7, 77.5, 155.0 .
The engine [383sbc, swirl port heads, small hydraulic flat tappet] currently has:
block hugger headers [very close to Pipemax spec], and
2.5 inch pipe with total exhaust lengths of 87 inch [left] and 107 inch [right]. This includes the turbo style mufflers' outside length of 18 inch.
Our intention was to fix the left and right banks' unevenness, and tune to the next harmonic length [155inch].
However, our [incorrect] estimate of the muffers' effective length of 54 inch [3 internal passages of approx 18 inch each] put our exhaust lengths at 123 and 143. We then welded 32 and 12 inches of actual pipe to the truck, taking our system to the 155 goal.
What we'd actually done was welded 32 and 12 inches to 87 and 107 giving 119. What was Pipemaxs' predicted 'Worst Length for HP/Torque?
116......
At least I feel a little better knowing why the truck went backwards

Back to top

 

Interesting thread. You'd tend to think that long tubes would have a huge effect on power. But I've heard so many different opinions of them over the years. No benefit to LT unless you have 500+ HP....LT must be used for every header and shorties have no purpose...well which one is it?

Regardless of the short vs long debate, I must say I was pleasantly surprised looking at long tube headers for C5 Corvettes. Long tube is an understatement. These things run half the length of the car! And they tuck up so nicely.



^^^ LG Street headers



^^^ ARH headers

 

"Long tube" headers for are cars aren't really all that long. They're more like a mid-length header for a full-chassis car.

 

there isnt much room to run a really long tube, but as long as the primary tubes are 24 inchs or over, they will have good scavenging properties

 

Here's another tidbit for the dicussion. Horsepower TV last week dynoed an engine with manifolds, and made 290 HP, and 326 TQ. Then they put on 1 5/8" shorty headers, and made 312 HP and 336 TQ. Then they put on 1 5/8" long tube headers, and the only thing they said was it made more torque down low. THEY DID NOT GIVE OUT THE NUMBERS! That says something to me.... Any one else catch the episode?

 

Yeah I remember that episode.

 

I have to ask this really stupid question, why not build long tubes with a 90 degree bend before the collector, that way you could fit the Y-pipe in the stock location, just seems a crap load easier...

 

Horsepower TV is the LAST place I would look for credible information. That "show" is nothing but a 30 minute commercial. Just like every other show on the Powerblock.

I have personally seen a stock LS1 pick up 40rwhp with long tubes and a tune. 20rwhp for each.

I put shorties on my car years ago but am considering a change to long tubes when the time is right simply because I am not impressed with the sound, or the power increase that I got from them.

 

Yes, its a commercial. But if they wanted to promote the long tube headers, they could have said how much more power they made over the shorties. But they didnt give the numbers. And that says a lot to me... I'm sticking with shorties. At least I'm saving on the hassle of routing a y-pipe with long tubes and a lowered car.

 

I forgot about this thread and was about to make a new one about my shorty header to longtube power. Late last week the hedman 1 5/8 longtubes went on my car. Previously I had the Edelbrock TES headers with 2.25 dual cat y pipe into two 2.25 cats (stock cats). I brought my car to a shop to install them, make the oxygen bung, and do a custom 2.5" dual cat y pipe into two catco cats i got from summit. I had planned to gut the cats, but they had the honeycomb and i didnt have a steel rod to punch through them. The exhaust guy flanged them for me so I know what I am doing when the weather is somewhat decent outisde .
Now, my dyno numbers from my last tune was around 340rwhp and 350ish torque to the wheels on a dynojet. I am going for a tune at Classic GT Motorsports Wednesday on a Dyno Dynamics 450 Chassis Dynamometer. I have been told they typically read lower than Dynojets. I will post up the results however. Stay tuned! Til Wednesday.....later!

 

Edelbrock headers are only slightly better than stock manifolds, so of course I expect a huge increase there. But we're all interested in the results, so be sure to post them.

 

Hooker made a set like that years ago for these cars.

 

Yeah, let us know how they new headers work out for you. Did you have to grind on the A-arm bracket?

How did you like the sound?

 

I think there are a lot of people who are interested in the results of your switch to long tube headers.

 

I did have to grind a small bit on the A arm, but not nearly as bad as ive seen some people do on here. The sound is more throaty...deeper...I LOVE IT

 

I'm going to say that a higher perf. engine will benefit more from long tubes than a stock engine. I'm talking about a 100-150+ increase over stock to see much of a gain by switching from shorties to long tubes.

However, there is more to header technology than "long" or "short" tubes. You will always see an engine produce more power with a header that compliments the engine better. It also has alot to do with where in the power band you want to see the power.

You could write a book here going into more detail. I won't.

 

Exactly...I didnt expect much of a gain at all but we shall see. I agree 100% on the remark about a higher performance engine will benefit more from LT headers than a stock engine. Same to say about going from 3 inch catback to 3.5 or 4". Its all in the power you are making.

 

Good idea, but the 1.5 primaries and 2.5 collectors limit them to stock/mild 305's

 

HAd to reschedule the dyno tune for tomorrow. My wife got sick...gotta take care of the family.

 

Alright just got home from the dyno tune from Classic GT Motorsports. Something odd happened on the first pull...It only put down 302 rwhp and about the same for torque to the wheels. Well different dyno's will yield different results. But one good thing from the first pull was that it was REALLY lean. It only made power up to 5000 rpms. Pretty odd I thought.
Well Nate Tracy went tuning away. After a few dyno pulls, he got me to about 328 rwhp and 330 torque to the wheels.
Since the dyno pulls were on two different dyno's, it isnt comparing apples to apples, however....a couple things:
1. Suppose I put the car back on Akron horsepower's dyno in Ohio....I would think it is pretty safe to say that it would put down somewhere in the 365-375 rwhp and about 400 ft lbs of torque to the wheels.
2. My stall was the stock stall on the Akron horsepower dyno and this time I had the 3400 stall.
3. I didnt retorque the header bolts after they were installed and I had a pretty bad exhaust leak at the gasket from the head to the header.
4. After the dyno tune, my peak horsepower was at 5300 rpms at Classic GT Motorsports, at Akron Horsepower it was at 5700-5800.

Overall I am happy with the dyno tune. I could feel the power difference on the ride home. I would recommend Classic GT Motorsports for a tune if you are in the VA or MD area.

One last thing.....tomorrow I am heading to MIR and will post the results back in this thread to actually show timeslips.

 

https://www.thirdgen.org/forums/orga...=1#post3757970

 

What is the point of those headers? One looks to travel down the center of the car like a stock setup, while the other looks made for sidepipes.

 

They both point to the pass side for a stock routing header back

 

thats a hella bad *** LT setup.

 

The 2138's are a really neat concept. I like'em. Thanx for the pic's Pocket btw. The problem with them is hardly the 2.5" collectors which equals 3.5" single pipe and should be good for between 300 and 400 hp. The 1.5" primaries however might restrict performance gains to the lower cube engines and/or unhigh rpm's. But if they could be made with squarish primaries instead then the flow area would rise from 1.5 sq.in. to 1.9 sq.in., making them surpass 1-5/8" round primaries at 1.78 sq.in. and also match the exhaust port shape better. Granted it would look somewhat strange but.. Anyone up to the challenge? I'll certainly buy such a set if someone makes them!

 

Looks like a P.I.T.A. to install those

 

No more difficult than any other LT install

 

It seems like if copied the design of the hooker 2138 headers to make them to except angle heads, with a 1 3/4 primaries, 3 inch collectors, and air tubes it would pass california emissions.

Kevin91z you should get don to make a pair like these, would definatelly be cool.

 

There are benefits to both short and long tube headers.
Due to the nature of cross plain V8 engines (Combustion events that is) it is best to try and get the exhaust manifolds to merge in as short a length as possible for scavenging reasons. This will dramatically improve horsepower but mostly torque in the low end but will not be as efficient at flowing large volumes of gas at higher rpms. Thats not to say there is not going to be power gained, a proper short header setup will own anything that came from the factory at any RPM with few exceptions. (More on that later)

Long tube headers will not be as efficient at lower rpm due mainly to the fact that scavenging is really not happening at all until much higher in the power band. The exhaust gases actually have to "Fight" against each other as they try to merge in the header (One reason why you see stepped headers just before the collector) At higher rpms the gases merging in the X pipes will overcome this nasty effect and work somewhat like its supposed to. (Note, you will LOSE performance if you do not use an X, H or some kind of cross over)

Back to one of the few exceptions, if you were to look at a F0RD GT supercar you will notice it looks like a pile of snakes. If you look closely you will notice something else, the first and last exhaust tubes from the right side are paired with the two middle exhaust tubes from the left side and visa versa, this type of system does not need an x pipe (Though it still may benefit from one) as the exhaust is scavenged at the proper events and thus does not have to fight to get out but rather it is "sucked" out by the previous event (To some degree) this is scavenging in theory and its one of the reasons (The main one in fact) that F1 and LeMans cars use flat plain V8 engines. It changes the event order so that exhaust gases will scavenge properly from there own separate manifolds.

The moral of this story (I wish I had time to get more in depth about all this) is that if you want a badass header(s) you will have to make it yourself and pair cylinder banks from opposing sides of the motor (It can be done! its just going to be a nightmare!) if you are interested in doing something like this I would suggest using a two piece design with flanges (That way you can get them into the car)

If anyone is interested I can point you in some directions.

 

https://www.thirdgen.org/forums/exha...rs-anyone.html

Read that
They are not restricted to "Ford Supercars" etc

Good luck fitting them in the engine bay
You can order these with AIR tubes thou

 

Not trying to steal this thread, but it's about something I was going to ask about.


Long tube headers from a GMC 350 truck (can't remember uhmmm might have been a GMC Jimmy ??) will they clear the frame/chassis on the Camaro ?

 

heck no, well maybe, but they will DRAGGG

 

My question is, how do Don's shorties match up to some LT's? Specifically on low-mid power?

 

In my situation I have been trying to kill off some of the low end torque for better traction. Unfortunately I have not been very successfull. This is with Dyno Don's shorty headers.

 

Not a chance. Only thirdgen headers will fit with thirdgens.
----------
We dont know anyone that has swapped Don's headers to long tubes or vice versa, so no idea on that one.

 

Arn't his headers based on another design? SLP's i thought maybe? Any info on SLP-LT swaps?

just to be clear, ground clearance and ease of install are 2 things i'm really looking for and i want to go with Don's headers (contacted him multiple times about it, just havn't got around to ordering) but i just wanted to check the possibility of LT's before i finalize my plans.

 

Well I ended up getting those GMC headers anyway, since someone took the entire engine with smog legal headers out of the Firebird I was checking out at the junkyard.

I'll check it out some time, too see how bad it is, if it's really that bad oh well clean them up, paint them, and sell them.

They had a 50 percent sale at the junkyards

 

There is a difference between store bought "headers" and real tuned headers. Ask the likes of burnsstainless, headersbyed, and Herb Gebler (gebler headers) and they will tell you that effectively what you get when you buy something off the shelf is a free-er flowing exhaust manifold. That's about it.

The racing guys will spend the extra money (BTW, how does $3000 for a set of headers sound) to get a set that matches thier tune perfectly.

For that you get a port matched header with all the primaries the same length and a length choosen for the engine's rpm range. To that, they add a carefully picked collector (merge style) tweaked to provide just the right amount of 'signal' (Gebler's term) to maximize power. With this, each cycliner will have the same tune - not one lean at low rpm and the other lean at high etc. -allowing for a more perfect tune.

Hooker Super Comps have traditionally been equal length headers. That is pretty much the only off-the-shelf equal length header out there (LS1 guys have SLPs) but the tubes are too large for 99.99% of the cars out there (and bit on the short side).

As one engine builder told me, if you install headers on a car and you don't need to retune (think carberator) you have essentially wasted your money.

The reason you don't see much gain in the average rag-azine test is two-fold. 1) They aren't tuned headers. 2) They didn't or they can't tune the motor because at one rpm one cylinder is working well (needs more fuel) and at another rpm yet another cylinder is coming on.

When you buy headers off the shelf, you get gimicks - stepped headers (uhm how did you decide where to put the step?), large tubes, short lengths, poorly designed collecters etc. So you get small power gains (infact so small, that it could just be different batch of gasoline, water temp etc.)

Remember someone actually loosing power with SLP long tubes on his LS1 car.

So, if you are only reducing some of the 'backpressure', there really isn't much gained by going long tubes. Higher horsepower cars might need larger volumes in their headers (note I'm not saying anything about flow velocity here) but that's about it.

I would look for ease of installation and clearance around spark plug wires.

 

It almost seems like there is some hidden agenda that won't allow long tube headers to admit they aren't that great for the average small block 300 HP engine. Case in point below.

http://www.fourwheeler.com/techartic...ers/index.html

When comparing the stock manifold vs short headers vs long tube headers, take a look at the difference in the exhaust after the headers. How is this an apples to apples comparison?



Some HP numbers from test above (short...long)

3200 RPM = 195...198
3700 RPM = 241...243
4200 RPM = 278...283
4700 RPM = 303...315
5200 RPM = 317...330

Sure the long tube/dual exhaust/X-pipe/dual muffler setup made more power. But I'm just not that impressed with the gains.

 

Its not a conspiracy, its just marketing.

But the bottom line is that it all depends on your combo. For example, I'm pretty confident that I will see significant gains swapping from the shorties/3in to LTs/4in. On a near stock combo...not so much. If it's not holding the engine back in some fashion, making it bigger probably isnt going to help you.

 

Reid you are correct in that is not an apples to apples comparison. What I have found with my own testing and those by others is that below peak torque the long tubes will generally have the advantage. Above peak torque there is no real advantage. Most of us are trying to kill off torque so that we can get some traction. The short tube headers need to be of equal quality, size and construction as the long tube headers for a valid comparison.

Formularpm let us know how it turns out. Post the short tube set up and the long tube set up.

 

Will do. I'm currently running SLP 1.75" shorties with a custom y, no cats and a Hooker 3" exhaust. Switching to 1.75" LTs, Mufflex y, and 4" exhaust. So this won't be an apples-to-apples comparison of long primaries vs short primaries.

Actually, I don't know that it's possible to do such a comparison with off-the-shelf parts - because as far as I know, there are no companies making 3" collector shorties with an actual Y pipe (not the stock-style contraption). Goes back to the longtubes often being more desirable for reasons other than the length of the primaries...

 

Im running a Miniram'ed 383 and my old exhaust was SLP 1 3/4 shorties and a Flowmaster 3" cat back system, I put down 375rwhp. I then swapped out to a set of Hooker 2210's and a Mufflex 4" cat back system with a custom made 3" Y pipe. I went back to the dyno (no tuning yet) and put down 413rwhp. I was happly suprised it made that much difference for my set-up!