Thats correct. When I put the pass side in the 1st time I put some heat reflective stuff on the lines and pulled them back with a hose clamp around the angled firewall support. But that's not enough.
When the #2 tube was fixed, it was shortened ok, but the tube now comes out at a different angle and contacts the fuel line. So now #'s 2,4, and 6 are in contact with the lines. I already checked the Jegs catalog and for the fittings and lines I'm looking at about another 100 bux.

If I had 1/2"-3/4", this would be a non-issue. Not sure I can pull them back further, but I'll find out for sure after I get the header back out and start "rubbin' on 'em".

 

Wow, I thought there would be 1/2" or more....

Keep looking for lines -- if you decide to buy them. I'm pretty sure I've seen them closer to $50. But, I can't remember where right now. (Probably in an HSR link in 3rd gen. That's were I looked at these lines for the Holley Steath Ram option.)

Don't rub too hard. What would you do if a Genie pops out?

 

I'd tell him to finish the burned-danged header install!!

 

Here are pictures of the pipe out & modified.

Notice the flattened area. This is needed to provide that last bit of reasonable clearance at the transmission. That's 1/2" .

You can also see some of the subtle changes in angle, the headers do not offer a straight shot.




The pipe on the left is a 2-1/2" SS. This replaced the stock 2-1/4" , just to give a feel for the difficulty getting all this metal in, around an automatic, with clearance .

It can be done, with a good fitter. [ that was NOT me].

A manual car should be easier. A LT much easier, but with that said, the expander is still a clunker that needs modification.




I went through this because I believe this construction is in fact the Collector for this exhaust.


Total cost R&d destroyed parts included, with Ceramic coating [going on Tuesday]. ............$345.00

If I had wanted to wait a couple weeks, David could have done this in SS mandrels, but I don't see much advantage?

TJM

 

Hi,

Here are some photos of the driver/side showing how I connected the accessory brackets. The heim joint (bracket) was a challenge as the opening had to be machined to fit the bolt. On the other side I had to add a brass bushing as the bolt was smaller. Both factory brackets were not modified. On the a/c comp. I added a piece of steel to reconnect the bracket (no big deal). Shims and spacers were added as needed.

As you can see all is very simple. Nothing was welded.

Steven

 

Steven, That looks very good. Very ingenious.

 

Steven,

Looks good.

I liked the idea of using the spark plug loom holes, too. Handy!

The pictures are a treat. They show the subtle differences between year models.

I notices you don't have that joint in the steering column, at least not where it is on the '89. Mine was real close!

Let us know how they run . Hopefully, you'll have better metric than " Seat of the Pants" to measure the performance.

TJM

 

Are you guys running mostly the 1 5/8" headers?

I've decided to re-read all my data on headers in the last week, based on some arguments with Greggpenn (Whom I respect).

I've always gone with a few theories based on my experience:

1) Primary length doesn't do much for a street motor
2) Primary diameter is more important


Gregg pointed out some David Vizards data, which I decided to re-read.

First lets touch on the subject of primary length.

Vizard makes note that proper length primaries can make more power on some engines, such as even fired inline 4 cylinders. He, like Lingenfelter make mention that 'equal length' primaries are a waste of time. He also makes mention that due to the imbalance firing of an SBC these combos are not "very sensitive" to primary length, and only have a "minor effect on power". IMO, this takes a LOT of weight out of the "long vs short" argument.

Now let's touch on the subject of primary diameter.

I've always gone by the theory that you want your primary tube size to be 110% of your exhaust valve or larger. This is old school hot rod math.

Vizard takes a more in depth mathematical approach at this, which further backs up my data but gives more understanding to header sizing.

Vizard's theory is that primary tubes have a flow density of roughly 80CFM per square inch, and that primary sizing should START at a diameter to support the max amount of flow your head will produce.

Most "stock" heads seem to flow under 130cfm, the worst being in the 117cfm range.

Most "aftermarket" heads flow 160cfm or better. My trickflows max out around 190CFM, AFR's have about a 5-8cfm edge on those.

Based on this Vizard math, lets look at two popular headers C4 owners purchase.

The Hedman "elite" headers are 1 5/8" 15 gauge will flow 133.74 CFM.

1 5/8" - .166 = 1.459 ID

Area = 1.6718621478590436 * 80 cfm = 133.74 CFM.

The hooker are 1 3/4" 18 gauge flow 171.47 CFM.

1 3/4" - .098 = 1.652 ID.

Area = 2.1434332693206293 * 80 cfm = 171.47 CFM.


So based on this information, I think we can conclude that 1 5/8" headers are ideal for stock applications, where anything with better flowing heads really needs to have at least 1 3/4" primaries.

In fact, for good aftermarket heads you really want at least a 1 13/16" header. I'm not sure such a thing is available for C4's, but it makes sense why a lot of C5 guys are running 1 7/8" headers on near 200cfm
heads. (exhaust flow)



So so far we have or, I have concluded that:

1) Primary length not so important
2) Primary diameter VERY important


The next thing we should take into account, and this really only effects naturally aspirated engines is the secondary pipe length + diameter.

Vizard says "Although primary pipe length is far from critical, the same cannot be said for secondary pipe length".

These Tri-Y headers seem to address the concern of secondary pipe length. Vizard continues that a longer secondary length favors low end, while shorter secondary length favors low end.

Based on the design of the Tri-Y headers I've seen on ebay, with very LONG narrow secondaries, and 1 5/8" primaries I think these are probably very good headers for stockish motors, with small camshafts.

Overall based on everything I've re-read in the past week, and obviously picking up a few things I've missed in the past I feel the Tri-Y headers are ideal for most near stock street cars, that will see sub 5,000 RPM shifts and have stock heads. I think it would be absurd to put them on a high flow, high horsepower, high reving car (such as an LT1, LT4) as the design does not support such an application - and for anything forced induction they are a total loss.

-- Joe

 

Joe,

Vizard is right on the primary length when considering 4 into 1 headers. 4-1 is the rage becsause of top end stuff.

However, the primaries on TRI-Y's [4-2-1] have a more critical function than 4 into 1

Check out Doug Thorley's web site he explains tri-y, well there.

They are a different animals, from the olden days, but they work , have been upgraded, and will be back.

He is dead on with the diameters. I have 1-3/4" on mine, [ but then I am planning on buying your Vortech when you decide to go with a bigger unit!!!]


TJM

 

In my reading, CFM/sq in was given as 115cfm/sq in (vs the 80cfm Joe reports). TBH, I don't know if 80 is specific to desired primary density. 115cfm was simply the # that will freely flow through any straight-thru exhaust pipe. It would seem intuitive that 115cfm/sq inches would also be the "limitation" for primary flow. If so, consider revising Joe's numbers (upward) accordingly.

To support my interpretation, Vizzard created a flow/sizing chart. It shows 1 5/8" primaries as being useable up to 180-190cfm. 1 3/4" picks up from there. Of course, the break-point could vary depending on where you want power. Smaller sizing provides better low-end boost whereas larger sizing provide higher boost and flow ceiling.

Vizzard also gave a race example where 18-24" secondaries were tuned to an 8K ceiling. (The Tri-Y headers are in this range and the advertised limit is similar). So, I don't know that you could conclude these are only for low rpm street motors. I certainly don't see that -- assuming Vizzard knows what he's talking about.

Joe, you also mentioned how secondary length affects where improvement occurs. (You should have posted that shorter lengths help @ higher rpms.) Brian seems to be open to the idea of custom-ordering a set with any length secondary you want. So, you could order a shorter length -- if you want to maximize high-rpm performance!

Joe also made an excellent point in long-tube header discussions. When you look at valve overlap for anything less than a race motor (i.e., 230ish duration @ .050" lift), the overlap period has in/exh openings less than .050". That's 1/10th or less of the valves travel. And, to be fair, Vizzard's tuning discussion seems geared to maximizing cylinder charging (thru overlap). Valve openings are much more significant on race motors. After figuring this out, I reread relevant posts and contacted "the experts". They ALL still seem to think long-tubes are the way to go. But why?

Certainly, you can't suck much intake down thru the heads if the valves aren't open that far, but you CAN have enough opening to allow complete scavenging of the old, burnt fumes. (Think of how much better an attic fan works if a window is cracked open). Also, overlap can (slightly) help cylinder flow at the beginning of the intake stroke (in similar fashion). This is how headers help non-racing motors. Long tube design does this best. One could argue that the Tri-Y design accomplishing this function at the lowest rpms with their secondary (tube) connection of "opposing" cylinders. Or it maybe not...

I could see the more common 4-1 design as using the pipe after the collector as the secondary. If so, the entire grouping of pulses from each bank would work together (after the collector) to scavenge fumes. An important element of this argument would be whether there's a termination box/area before the exhaust exit. This area would determine the length of the secondary and how it's tuned. If no low-pressure (larger area) exists before the exit, this configuration of 4-1 could be tuned extremely low. In fact, lower than the Tri-Y's. If so, I submit that long tubes setups might perform (on dynos better) if a low-pressure area was added.

So, Tri-Y's could still be the better high rpm setup -- if you simply dump them into a larger output pipe (as the low-pressure area).

The most disappointing thing about Tri-Y status (for me) so far is the dyno that showed poor high-rpm performance. Personally, I think something other than the header caused this problem -- but we've never heard back from "Bandit". With the few number of buyer's in this forum I don't expect to see additional (dyno) measurements anytime soon.

OTOH, the most impressive thing so far is the torque that was measured on Bandit's car. At 373 ft/lbs (on a stock motor), it represents a potential power gain of nearly 10%! From headers only, that's impressive. It should be something you could feel.

gp

 

You were pretty set on quoting Vizard in every discussion, so I pulled up his data.



Again, you proposed the Vizard standard. Lingenfelter, Ben Watson, Pat Ganahl all go by the 110% of exhaust valve diameter.

Again, Vizard. I think we need to settle on a standard. We can't quote one author when the argument works in our favor, but then disregard his other info and go with another guys because it makes our headers seem better fit for us.


I'd re-read the data if I were you. Another thing to keep in mind,
to calculate CFM you guys need to measure the INSIDE diameter of the tube. Which requires measuring the OUTSIDE diameter, subtracting the wall thickness, then calculating area based on that. Obviously different brands of headers with different wall thicknesses will have different inside diameters and flow VERY different amounts.


Again, re-read the data and tell me if I misinterpreted something he wrote.

I think it's obvious, and I've stated numerous times I agree long tubes have a slight edge over a short tube design. I'm not convinced everyone needs long tubes. I admit, after having a warped flange on my short-tube hooker 2061 I was unable to find another set of short-tube headers with a large enough primary size to support my engine, and had to 'throw in the towel' so to speak and buy long tubes. I'm not happy about this.

Another thing is, my prior experience with "short tubes" meant fbody, and gbody short tubes. The 'y-body' shorties are more like block huggers. I think the 2151, 2149, EM, etc are all too long, but I also agree the transition from primary to collector on the hooker + pace setter shorty is too fast.


My points are more to emphasize the primary tube sizing. A lot of people say "hedman elites" when I don't think those people are looking at the data enough.


I have not seen a 1 3/4" version, but IMO (yes, just mine) they are a good header for a stock L98 or LT1. TO spend $600 on them for an aftermarket head/cam combo seems foolish to me. They, like the hedmans, don't appear to support a hot motor.


I'd expect that. If you talk to the 4x4 rock climbing guys, they've been running similar small-primary, tri-y, long collector designs with great success for 20 years.


-- Joe

 

I'd expect that. If you talk to the 4x4 rock climbing guys, they've been running similar small-primary, tri-y, long collector designs with great success for 20 years.


-- Joe[/QUOTE]

Who would have thought one little question last September would span this freaking saga? I think Scott Mason should be proud

Anyway, you guys are great. I don’t need to crack a book! [ no, I am not being sarcastic].

Tube diameter for primaries is only one part of an equation. How about:

• The length of straight tube at the heads? Short slows gases?

• The angle of the primary is another. Turbulence.

• The degree of the first bends. More turbulence

• Materials [ heat soaking] is another. SS or Mild steel ? wrapped or ceramic?

• The length of the primaries is crucial [ especially on theses
things] .

• Secondary size, How about the fact there ARE secondary’s.
4-1 create a cluster. at the end, unless your really screaming.

[ the motor, not you].

• Collector [ Oh there isn’t really one... Odd? ]

• I wonder what “1-1/2” stepping in the 1-3/4”, at the flange
would do?

• The Goofy Pickle and the Secondary’s into 2-1/2” into 3” thing?

Best of all
• How will the super chargers like them? [ I betting more than
junkies like dope].]

Oh, all the physics aside, they pretty much fit, better than average finish, have a massive flanges, good welds, and give great ground clearance.


TJM

 

Good points Joe. I see the reference to 80CFM at the end of the graph you posted. But look at sizing presented. Once you go head below 180 cfm, you head toward the 1 5/8" recommendation.

I have to assume this chart is for all-out racing as well -- meaning for rpms that extend above 6k rpms. Also, I'd assume street applications can go with smaller sizes for more low-end umph. Put another way, we could subtract a percentage of primary size for motors that primarily stay under 6k rpms. You do make a good point about ID. I believe these headers are 1 5/8" OD. So, the inside is a little smaller. Wanna consider an offset for these two points?

Consider also that 1 5/8" primaries would allow over 16 sq inches combined cylinder output! Even if you install dual 3" exhaust pipe, you only provide 14 sq inches of cross-section behind the headers. You could argue it's well matched -- keeping velocity high; you could argue that combined pulses don't need as much room; or you could argue that a larger, low-pressure exhaust is required. But rarely does anyone argue for exhaust over 3" duals.

When you take into consideration the issue of valve overlap and Vizzard's recommendation to err on the side of being too large (for primaries), there's no reason to assume that 1 3/4" is too big for stock motors. Certainly, you've taken care of restriction. But, your point is whether 1 5/8" is too small, right?

Based on the consensus that you don't need dual 3" exhaust for motors in the 350-500hp range, I could see where 1 5/8" matches dual exhaust pipes in the 2.5-2.75" range. And, the smaller size would improve lower rpm exhaust gas velocity.

But, this is theory. Since you insist 2" dual exhaust can go on a 500hp car, I think 1 5/8" primaries can go in front of it. It's a math thing -- and not Vizzards math.

gp

 

Not really. We just like to argue!!

 

This I cannot answer brother. I've personally always gone by the 110% of exhaust valve diameter method, which for a 1.60" exhaust valve is 1.76". When you figure most 'out of the box' aftermarket heads flow around 180-190cfm this does follow the lines of Vizards math, but I think Vizard presents it in more detail.

Either way, I brought the Vizard stuff up based on your previous thread posts and I agree with most of what he's saying.


Another good question. Considering most 'street' motors are both under 400 crank HP, and shift below 5500 RPM's I still say for a majority of these combos the smaller tube tri-y is a good design. Do people put AFR 195s on small street motors? probably not, Slightly ported 113's and Lt1 heads are the more likely scenario, and cams with around 212-218 degrees of duration. But now were back to the 'how much does the scavenging effect really have with those smaller cams?".



Typical exhaust gasses travel at what, something like 320 feet per second. It would take me a while to try and figure it out mathematically, but I'm willing to wager only a very small handful of cyls spent charges are in the exhaust at once.


I don't know if I buy into that theory. Again we're uneven fired, so we're not filling the exhaust up like if all cyls were going at once. I think in the primaries where exhaust velocities are highest we want as little pressure drop as possible. I think sizing the primary tube to support at least the same CFM of the exhaust port, and erring on the side of 10% more is a good starting point.

You bring up a good argument, I'll admit. The rule of thumb is what, 2.2 cfm per horsepower? But what does that really mean? At 100% VE?
If a car dynos at 500hp at 800cfm, what does this prove? How much of an impact does the pressure drop in the exhaust system really have?
It's really hard to say.

I guess I can't say my Formula didn't have backpressure. Maybe it would have went 130mph in the 1/4 instead of 120mph if I had larger exhaust? I don't know for certain. I *know* a single 3" pipe with a cat supported 120mph in a 3675lbs car. I guess I didn't bother trying larger exhaust because when I simulated the engine combo, the numbers were within a few percent of what would have taken to accelerate a 3675lbs car to 120mph in the 1/4. Now, if the simulator suggested a 650hp combo, and the car only went 110mph in the 1/4 I'd question an exhaust issue...

How much power do you think it takes to send a 3675lbs car to 120mph in the 1/4, with a manual transmission and 8" drag radials?

-- Joe

 

Eh, with forced induction intake pressure is always higher than exhaust pressure, so really the only thing of concern is getting the exhaust out of the car. I think primary length tuning has a small effect on N/A motors, and ZERO effect on a boosted motor. Primary stepping and collector length similarly should be of no benefit. On a supercharged motor it really is about eliminating pressure drop on the exhaust and just getting the spent charge out.

I also happen to be more into blowers than N/A combos. I got hooked on blowers some time ago.


-- Joe

 

So I gathered. I bought 1-3/4" with just that in mind.

Now I am searching for a "bargain".

I think cold air and boosting is preferable to mechanical modifications.

Easier on the parts and is getting to be very cost affective for a garage hobbyist.


TJM

 

My powerdyne cost me under 2k. On my formula my vortech setup was about the same price. I had an a-trim then an S-trim, overspun.

I spend more playing with other things. This winter the miniram is going up for sale and getting replaced with a singleplane. I've had a lot of success running a singleplane with a monoblade TB on my Formula.

-- Joe

 

OMG!! I think we're in agreement!

If I have 113's fully ported and add a cam under 220 duration, I'd expect 180ish cfm on the exhaust port. That's in (Vizzard's) transition range where I could select either size header (1 5/8" or 1 3/4"). I'd expect 350+ crank HP and I'd shift my ZF by 5500-6000 rpms (when getting on it). Lower rpms (than a racing motor) tell me the smaller size makes good sense.

If, OTOH, I opted for TFS 175s or even AFR 180s (which have the larger 1.6" exh valve), then increased exhaust velocity might demand the larger size. But, w/o a different bottom end, the improvement might be minimal. And, staying under 6K rpms might leave the 1 5/8" on the table. For me, cam selection would dictate the final choice. A cam closer to 230 or above would represent the goal of building a high-rpm motor -- and require larger primaries. A cam smaller than that probably means you're not racing and could use the smaller tubes -- IF -- there's really improvement thru port velocity. (If not, you're probably not restricted much anyway).

After looking at porting (113s) and the optional aftermarket heads available, I see 1.6" valves as being the transition point where heads start flowing > 180cfm. So, you're rule of thumb (by valve size applies). But, I'd temper the choice by goals. IOW, maybe the smaller size could still be used for a "street" car.

 

Interesting... I decide for the head/cam swap (vs adding a blower) by thinking the opposite. I felt pressurizing the 20-yr-old stock motor could lead to more problems than rebuilding the top-end for N/A gains. And, it would be resealed to prevent old-age leaks.

I do think these (1 3/4") headers are a good choice for a blown street car though!