Black88Z

I'm building my 350tpi up and was planning on doing long tube headers with 2 1/2in dual exhaust with x pipe. I've talked to a few people and they said that shorties with 3in exhaust would be better for me because my engine would redline at about 6k rpm. They said for that the 3 in would provide more back pressure and result in more power. I thought that was crap, but maybe I'm wrong. Open to all opinions and suggestions..

Thanks

VincentZ28

iTrader: (2)

First what is done to the engine. 2nd what are you going to use the car for. 3rd shorties are alot eaiser to install. In your case , a set of Dyno Dons are the best way to go for shorties. If your car is a single cat car or dual cat car then he has them both. Dual cat makes more power than single cat. Get a good 3in cat back system like Magnaflow and you're good to go. Don't get fooled by the long tubes. The power difference is only 1to three HP at the most. Its been proven.

InfernalVortex

iTrader: (4)

First, read the backpressure sticky. Ignore what those guys said, its not about backpressure, it's about velocity and wave tuning. Backpressure is a mostly irrelevant secondary quality, but one that's easier for simpletons to visualize and make incorrect assumptions about.

Second peak hp differences are very small. LT's will make BARELY more peak power.

Third, due to the longer primaries, the main difference between LT's and shorties, is the long tubes make more torque (and necessarily more horsepower) in the lower RPM range. If you have a very large cam (that spins to high RPMs) that would normally be very lazy low in the RPMs, the increase in low-midrange torque from long tubes can make a difference. You get more torque under the curve. after peak torque it begins to level out near what shorties do as you start to near peak hp. Any cam that will work with a TPI will be very small, and the TPI will ensure you wont make much actual horsepower anyway, so you wont see much gain at all from LT's. With a miniram and a big cam you probably would.

Fourth, the advantages of long tubes are usually far outweighed by the disadvantages of packaging an exhaust system for them. Do you like having 2 inches of ground clearance for an extra 5 hp on a 400hp motor? For anything running a TPI, the aforementioned 1-3hp is probably about right.

skinny z

Quote:

Originally Posted by InfernalVortex

... its not about backpressure...

True.
Zero back pressure is the ultimate goal.

These are the two most basic considerations when developing an engine program.

Quote:

Originally Posted by InfernalVortex

Second peak hp differences are very small. LT's will make BARELY more peak power.

I'm not so sure about that. What an LT header provides is a greater range of selection regarding exhaust tuning.(And this I klnow Infernal knows) If an optimum situation could be created, I think you'll find that the greater selection in primary length allows for a better fit when developing an engine program.
I think it's safe to say that, with Don's short header, when combined with the TPI intake, the result is a excellent combination of parts. Hence the horsepower numbers they achieve.
Further to that, LT also provide a secondary or collector that can be tuned for what really is the greatest advantage of an LT design. Secondary dimensions (diameter and length) have a far greater impact than does primary length. This is not considering the primary diameter which is another thing altogether and can be designed into either style of header.

Quote:

Originally Posted by InfernalVortex

.... the advantages of long tubes are usually far outweighed by the disadvantages of packaging an exhaust system for them...

Quote:

Originally Posted by VincentZ28

... shorties are alot eaiser to install...

And that's probably the single greatest reason to choose Don's headers over an LT design. Unless you live in California where his smog legality weighs heavy on the pro side of the equation.

Ozz1967

iTrader: (4)

This is your number 1 priority, do you need to pass any kind of emissions test where you are? In **** Cali, Hooker 2055 shorties are the only ones legal, not sure if Dyno Don has his past the CARB yet. Before Dyno Don's, those were the best shorty headers you could find and were most recommended on the board (It's what I run).

Also, 3" single exhaust flows maybe 5 cfm less than dual 2.5". Also, if you have an auto car, long tubes will creat a huge clearance problem as was already mentioned. I've been wanting dual exhaust forever, but with an auto tranny, it's just not really feasable, even if you oval out the pipes for a little better clearance.

Black88Z

Ok, thanks for the info. I guess me and the people I talked to were wrong in some aspect lol. I had originally planned to put shorties and 3in exhaust on, then was going to do longtube since I thought that was better, but now ill do shorties and 3in exhaust. I have some shorty headers already but I'm not sure what brand they are. They're design is like the dyno dons though. But ill look into the dyno dons and 3in exhaust and go that way.

Btw, I'm planning on 350hp at the crank, so LTs probably wouldn't even make a noticeable difference.

VincentZ28

iTrader: (2)

That's cool! If you were to spin the engine pass 6500 all the time then LT are the way to go. Since you're only looking at 350hp at the crank which is about 285whp Dyno Dons are the way to go. Or if you can find SLP 1 3/4in headers like Dyno Dons for cheap then go that route. I have SLP 1 3/4 headers for the past 13 years and made 408whp with them. Topteam54 made 431whp with Dyno Don headers.

skinny z

At that power level, probably not provided the rest of your combination works. The california guys (and others here) are well beyond that as witnessed by their 400+ hp at the wheels.

Edit. I see Vincent beat me to it. But only by a 1/10 or so.

ringo234

Dyno Don's headers are the only headers with 13/4" primaries you will find, Hooker 2055 are only 1 5/8" primaries. I don't think SLP makes 1 3/4" headers anymore.

skinny z

For a 350 hp build ( and considerably beyond), 1 5/8" would be the way to go.

ringo234

Why is that the way to go? That doesn't makes since to me.

skinny z

Without getting into the science of it, a smaller diameter primary pipe promotes low end torque. The same can be said, although to a lesser degree, about a longer primary length when choosing a header.
That's what your after in a mild street build.

BlackenedBird

iTrader: (5)

While Dyno Dons headers are nice, just remember 2 things about them.

They are not smog legal certified. Yes he can put A.I.R. tubes on them to APPEAR to be smog legal, but they have never passed certification & have no E.O. # for them.

They are the most expensive 3rd gen headers available. Now....Is the higher cost for them REALLY worth the price difference compared to other headers out there?

VincentZ28

iTrader: (2)

Yes they are because you can not buy any other headers other than SLP that are 1 3/4in tubes and has the best spark plug clearence with all type of heads.

VincentZ28

iTrader: (2)

Can not buy into that with shorty headers. Those other shorty headers has restriction in them in how they flow the exhaust through them.

one92rs

iTrader: (5)

AGAIAN IT IS NOT BACKPRESSURE. it is velocity and exhaust pulse. every time a cylinder exhausts it is a pulse. you want the pulses to come right after another in an exhaust system as they travel out. too big an exhaust and the pulses disappear. too small an exhaust and the pulses back up. NO VELOCITY VS TO MUCH VELOCITY. the correct way to look at an exhaust is to be the correct diameter tuning along with the correct length. this way when one pulse comes out the next one is there at the right time to push it out along with all the other pulses. what is created with a tuned exhaust system is a slight vacuum between pulses that would pull the exhaust out to the exit. so IMHOP. backpressure -----meaning----poor exhaust system

Guest

...YES! I will eventually sell my 3 month od coated 2055 kit and hassle Don into doing a C.O.D del with me....sending $800 to a complete stranger across the country...couldn't do it...

(im doing a BOOST build and I NEED the BEST I can get. (bigger header means (for me) more flow, more power, less cylinder pressure. <-HUGE plus!
Also I HATE the Y pipe design of the 2055s...horrible to say the least...

ringo234

Hey If you don't trust dealing with Don directly (no one has ever not gotten the parts) you can get them from Lon at http://www.top-downsolutions.com/. He sells them for Don.

Guest

The Y pipe is NOT COATED!!!!! NO!!!!
i may still buy someday anyway....

skinny z

I wasn't taking about the shorty design (and the restriction you mention regarding flow) but more about the theory and how and engine responds to the various header lengths and diameters.
Trust me, if I was in the market for a shorty style header and had the need for a 1 3/4" primary pipe, I'd buy Don's headers in a heartbeat. From what I've seen, they are amongst the best built available today.

skinny z

This is correct except the vacuum is not slight. With a properly spec'ed header, one that's designed with attention given to primary AND secondary dimensions, it will produce a negative pressure pulse (vacuum) which is far greater than that of the piston travelling down the bore. Often referred to as a 5th component of the 4-stroke cycle, it's what seperates the best from the also rans in the racing business.
Combine this exhaust tuning with an equally thought out intake design (as many of our Cali friends have done with their heavily moidified TPI's) and you have an engine that outperforms the rest.

IROCZ1989

iTrader: (1)

Read this thread


https://www.thirdgen.org/forums/exha...280-385-a.html


I made the switch to SW longtubes. And they dont hang any lower than stock if you get the 2 1/2 primary. They actually fit well, are well made, but pass a little consuming to get in.

VincentZ28

iTrader: (2)

The real difference in power is the routing of the pipes. Long tubes goes straight back pass the Trans. The shorties has to cross in front of the Trans which means more bends in shortys. Less bends with long tubes. If you can measure or compare up with the headers open the HP will be very very small.

IROCZ1989

iTrader: (1)

So you think shorties open vs long tubes open would be the same hp? But in practicality the full length system is closed as most would run on the street. So open shorties match long tubes hooked to a cat back?

VincentZ28

iTrader: (2)

Both systems close the LT would be better if you reving the engine pass 6500 and a track car with true duals. Our cars are not set up true duals so we are limited. Being in California has us restricted. This is why we try to do things the right way and to show that big HP can be made with the shorty set up if do e right.

They guy on the other board used a larger system. Bigger pipes. If you do the same with shortys you'll make more power.

IROCZ1989

iTrader: (1)

From what i understand about that dyno, only thing that changed what the headers system+ the gains on the sheet are from 3000 and up, dyno stops before 6500.There is so much info about exhaust tuning and scavaging and alot of info on collectors design on the impact of tq and hp , its tough to say there is no difference between the two and only if your reving it to 6500. The dyno sheet doesnt even go that high. On the sheet hp #s are even until 3000 then the long tubes pull away. Same with the tq numbers.

VincentZ28

iTrader: (2)

1989GTAtransam did an engine Dyno with both headers install. The difference was about 3 HP for the LT.

IROCZ1989

iTrader: (1)

Really? Seems like conflicting info then. Maybe we can get both posters in here to comment. What brand were the longtubes? In my experience and I can only speak of mine, the SW headers are very well designed compared to supercomps. Best welds I have ever seen on ss headers. Most likly tig. Guy is an artist. Plus the collector design is steps above the supercomps. Maybe we can get both in here. Alot of guys run shorties but not many run full length from what ive seen.

IROCZ1989

iTrader: (1)

So many variables as well. There are poorly designed shortys and poorly designed long tubes. So a poorly designed shorty replaced by a quality designed longtubes will skew results and visa versa.

IROCZ1989

iTrader: (1)

Yes im glad I dont live in your state. After 15 years old our cars becoome emmision exempt. But if you had a 4 inch system mated to a cat why would that not pass emmisions? Or have a set of longtubes and add the air pipes. From what most you guys run, the dyno dons shorties they are not certified emmisions legal anyway right? Air tubes and high flow cats and egrs dont hinder performance as much as some might think. Im just glad I dont have to deal with that bs here.

VincentZ28

iTrader: (2)

They have us screwed here. Our car will never be exempt. They will be crushed before they become exempt.

I have SLP 1 3/4 headers. We have to find certain stations that will over look them. The smog people will look under the car looking for cats. They check everything. Even the gas cap. So that's why we keep ALL the emission on the car and work with it.

BlackenedBird

iTrader: (5)

You have the misunderstanding that exemption means that you can remove everything. Not true. Exemption means that it doesn't have to be tested, but everything still has to be in place visually.

skinny z

The rules here in Ontario, (Canada) are similar. Any car manufactured after 1986 does not need to pass a bi-annual smog test however any installed emissions equipment must remain with the vehicle for life. We have periodic road side spot checks where visual test are conducted as well.

IROCZ1989

iTrader: (1)

Understood, but the heres the deal with ma. Few years ago they made all the shops get dyno rollers to test the cars at the tune of almost 50,000 dollar setup. It never worked right always problems. So when 2-3 years later they said they were doing away with it most shops said screw this and gave up testing all together. So now not all shops do it and the ones that do almost always have 2-4 cars waiting. So they do the safety and dont even pop the hoods anymore, time is money. Think of it this way, if the stuff is there or not does ot really matter if the car passes or not if its not being tested? Not many cars on the road after 15 years and of they are they are either well taken care of daily driver 4 bangers or cars like ours. Trust me my father runs a guys shop for him , gm certified, been doing it since 77. He left gm because no ones doing it anymore and mechanics, goods ones and people in general who actually get off there buff to work these days are few and far between. So think of it this way. If an owner has one good mechanic because he obviously can pay two well, hes not going to tie up the expert doing stickers. Hes gonna pay a lump 8-10 bucks and hour and when your charging 29 for a sticker your not going to waste time om stuff that doesnt matter either way and prolong a test on older cars when it adds 10-15 min to the test on cars not needing it. Simple buisness in this **** economy.

VincentZ28

iTrader: (2)

My tags cost $123.00. Cali is a rip off.

VincentZ28

iTrader: (2)

Lets get back on topic. As far as headers goes, what ever the car will be used for, use those headers.

bestracing

I thought the SLP Tri-Y headers had a CARB#

Either way I bought an 87 Formula that had the entire SLP exhaust on it and when I sold the car I kept the exhaust and put it on my 86 T/A. Now my observations with these headers.

Good:
A lot better than the stock exhaust.
They don't really rust
Thick header flanges that don't warp over the years of use.
Easier to install than long tubes
Thick wall tube construction, holds up well over the years (also a small problem see below)

Not so good:
#1 Out of production.
On mine the headers don't line up to the head. I have to pry the last tube out to bolt them up.
The air tube would crack at the welds. I cut mine off and installed plugs.
The supplied u-bolt clamps wont crimp the thick wall tubing enough to seal the exhaust and had to buy band clamps.
The header to y-pipe flange gasket from SLP was expensive and it's better to make your own. Not even sure if they still sell them.
Have to have a shortened spark plug socket to remove a couple of the plugs.
Have to use plugs that are externally shorter on two cylinders or the plug boots (MSD) touch the primary tube.
The deep bolt sockets in the primary header flange can cause some problems with the generic 7/16" head, bolts. I used the ARP, 3/8" 12-point head bolts.

If these were still offered brand new I would choose a different header because of all the little problems and they were too expensive. If I found a good used set at the right price I would buy them again.

IROCZ1989

iTrader: (1)

Either one will give a boost in power. Long tubes like the Sw units are made of a better quality 304 ss which although change color they dont get rust colored like the 409 units. Plus the flanges on the SW headers are made to use permates sealer saving you alot of money in gaskets if you ever remove them, or remove them often. I always opt to coat the headers reduces the tinny sound that iron manifolds cut down on. Plus keeps the heat down a bit in the engine bay. I have no horse in this race and dont know anyone who sells headers and am only recommending what I have because Im happy with the quality and fitment. If emmisions is a concern then by all means a carb eo certified.

VincentZ28

iTrader: (2)

I agree with everything you just mention except I used the factory spark plugs(AC Delco R45TS) and they clear all the tubes with no problems. They don't warp but what they do is since they kinda srink a little because its not a solid piece. I had my flang cut off for a ball-in-socket flang. Never use a gasket there. They only come second to Dyno Dons.
On angle plug heads, you may need to use shorter plugs. I just use the standard size plug for Corvettes. They are shorter that the cast iron plug.

ringo234

He will coat the Y pipe but will cost extra. You could always coat it yourself.
Either way you won't find a better exhaust system.

Oh since those pictures were taken he know longer uses ordinary steel he uses Aluminized steel.

""Aluminized steel is steel that has been hot-dip coated on both sides with aluminum-silicon alloy. This process assures a tight metallurgical bond between the steel sheet and its aluminum coating, producing a material with a unique combination of properties possessed neither by steel nor by aluminum alone. Aluminized steel shows a better behavior against corrosion[1] and keeps the properties of the base material steel for temperature lower than 800°C (1,472 F). For example, it is commonly used for heat exchangers in residential furnaces, commercial rooftop HVAC units, automotive mufflers, ovens, kitchen ranges, water heaters, fireplaces, barbecue burners, and baking pans.""

IROCZ1989

iTrader: (1)

So the consenses is all CA guys like shorties? Been reserching this topic more and more. And the more you look the more questions ccome up. Seem the concensus on here and the vette and lt1/4 boards is long tubes always make more power on the dyno. Seems people who switched and did a retune for the long tubes found gains. So they gained some switching and when retuned gained even more. Some things ive been picking up on is on cam overlap, seems cams over 60° gain more on the long tubes due to scavaging. From all the dynos and threads ive read the over all picture is with both exhausts you gain by putting in the biggest midpipe you can get under the car with the highest flowing mufflers. So if you can get a 4 inch under neath the car and dump it through a bullet muffler its the best bet. When you do the cross section area of a 3 inch mid pipe its like running sub 2 inch duels for exhaust cfm. Now who would run say 1.75 inch duels on a 400hp motor your turning to 6000rpm? Another cork is the cross flow muffler. Seems to be a more of a system approch than a single component. And when done this way the longtubes will make more power and support more power for other future mods, like nos . or boost. But if emmisions are an issue it seems like shorties with an eo # is your best bet. So to original poster if you have emmisions to deal with get the eo shorties. Idk any longtube that is eo exempt for our cars.

IROCZ1989

iTrader: (1)

Good old thread on pipe diameters. Love google...

https://www.thirdgen.org/forums/exha...st-single.html

skinny z

Exactly the reason for cam overlap and headers in the first place. The overlap combined with the tuned approach to headers, and more precisely the tuned approach to secondary length, is what makes for a well scavenged cylinder. That secondary length has to be determined (through testing or software such as Pipe Max) and incorporated into the chassis of the vehicle either through exhaust cutouts or an Exhaust Termination Chamber (that's a story in itself). This is what "tunes" the length. Engines designed with smaller overlap cams, such as though used with EFI due to the wider LSA's see less benefit with tuned exhaust than those designed with tighter LSA's, greater duration and the subsequent increase in overlap.
It's interesting to note that a shortie header, with it's reduced primary length, is not the limiting factor that some make it out to be but rather the attention that's given to the collector or secondary attached to it. Typically they're routed through a y-pipe and little attention is given to the functional length.