Hehehe. We are waiting. I will stick with my 400rwhp initially. You will most likely wind up with more horsepower with the tuning. Your car is about 300 or so pounds lighter than mine ready to race. That is 3 tenths of a second. So if I ran a 12.29 and 370rwhp that would put me right around 12 seconds flat at your weight. So your car is 3 tenths quicker than that with equal weight. That is around 30 horsepower. So 370rwhp plus 30 equals 400rwhp. That is my story and I'm sticking to it.

haha good guess. i'm gonna go with 395 on first pull and 415-420 after tuning. hopefully thats conservative

Vizard also has an interesting analysis regarding primary length vs secondary/collector length and shows how not only is secondary length worth a lot if tuned properly but that it's easy to adjust especially considering how primary length is fixed once the headers are in.
Open collector testing would be worth a lot on a dyno if somebody has the time and the tuning capability.
Then we figure out where to put the t-boxes.

11.3's @ 116 mph and 3500lbs works out to about 420 rwhp according to my handy Moroso Power Speed Calculator.
That's my vote.

if i estimated right i should be right around 3425lbs raceweight hard to say tho, the 4" exhaust may be a tad heavier than the last system and forged internals may be heavier than stock motor internals but i'm not sure

i've added aluminum water pump worth 10lbs or about that, aluminum heads worth 50lbs off, and LT1 starter worth atleast 15 lbs off if not 20lbs. Big difference. I havent gutted anything else
Last year i was 3460 with 1/8 tank race weight gas setup I would think i'm near 3425 or less


i cant wait to get a rough baseline to then play with CAI and stock MAF/TPI intake lid stuff, and then collector tuning

[quote=Orr89RocZ;3834551] I would think i'm near 3425 or less


QUOTE]

Mr Moroso says 410 rwhp then!
Good luck.

Hey fellows working on another 3rd gen true dual system with a terminator tube. And yes we WILL see how much hp is to be gained since we do have a before dyno run. Should be done in a few days then going to the dyno to show the owner how much trq/hp he left on the table. Doing three runs, dyno with just exhaust, dyno with exhaust and best tune and dyno with open headers. I'll keep you guys posted.

Thanks TheBadazz. Looking forward to the results. Pictures would also be great.

Here is a followup post by Larry Meaux and rates what gives the biggest gain for the exhuast. Looks like Dyno Don's shorty headers might be almost as good as long tubes if everything else is correct. Here is the post and you can take it to the bank.


"i just Dyno tested a 420cid SBC recently
with a pair of unequal Length Headers.
The longest primary= 36" inches
the shortest= 22" inches
the rest were in between
but the Collector was the right diameter and length
so that Engine made good TQ and HP

those particular Headers are 4-1 style and there just for
Dyno testing if any Customer wants to try them out
against their Headers and also to see effects of Header sizes/lengths
-VS- their Headers.

the thing about the 4-1 Primaries being Unequal in Length
will still sometimes tune-in on one of the 3rd,4th,5th, or 6th Harmonics
by accident or design...just depends on their individual lengths


i keep a few different SBC diameter sizes
like from as little as 1.500 Primary OD to 1 7/8ths for
Dyno testing + research.

from what i've seen,
as long as the Collector Diameter and primarily the
Collector Length coincides with 4th Harmonic
the TQ and HP Numbers will be good .

getting the Primary Lengths perfect is not worth much TQ or HP
on a 4-1 V8 System


i might also add->
playing with Primary Pipe Diameters
and with Collector Lengths and Collector Diameters
are where you are going to shift the TQ Curve around
and where you are going to find the greatest TQ and HP gains !
i'd rank the Primary Pipe Lengths on a 4-1 V8 system
as least important !
_________________
Meaux Racing Heads
MaxRace Software
ET_Analyst for DragRacers
www.maxracesoftware.com

It's understood that unequal length primaries will distribute the torque over a broad rpm range however isn't it also the case that short tube headers tend to move torque peak and horsepower higher in the rpm scale? Short tubes, large diameter = high rpm. Long tubes, small diameter = low rpm.
As far as the dyno testing goes, I'm looking forward to the results.
Are there specs on the current and already tested exhaust system?
And most importantly, specs on the terminator boxes (and where they fit!).

Well the motor is a mild 350 efi with a mild cam and ported heads and headers. The old setup dumped into a 2.5 inch y pipe that went into a mandel bent 3" exhaut pipe with a mangnaflow camaro style muffler. Car dynoed 340rwhp 350rwtrq.

New setup is dual 3" coming from the headers (22" and 24" long) into a 4" y-pipe that is 57" long over the axle, splits to dual 2.5" mandrel bent tailpipes into magnaflow ultraflow round mufflers with some nice stainless stl tips. This cars last race is on u-tube and I will try to video the car when I tune it on the dyno for you guys.

heck i'd love some shorter/mid length tubes so i could have get my ground clearance back. the longtubes are fine, but the y pipe inorder to get them to work with the auto spohn xmember isnt

Cant wait to see the results on the exhaust test TheBadAzz

"heck i'd love some shorter/mid length tubes so i could have get my ground clearance back."

Well if Larry Meaux is correct the collector dimensions are the most important thing regarding the exhaust with length number one and diameter number two. 3rd on the list would be the primary pipe diameter and the last would be the length of the primary pipes on the header.

So mid-length headers might not be bad at all with a good termination box.

I would agree with that.
There's a post here somewhere of a racer who is using a short style header and a collector of 18' or so. Apparently he is getting pretty good results.
Out of interest Cypress, why hasn't anybody received a CARB number for a long tube header?

you guys are making plenty of power with dyno dons so i shouldnt hurt much with those pipes.

eh maybe i will get shorties if i do a blower or turbo...then i dont need to worry about the exhaust as much

Tomorrow is Thursday. I hope the dyno pull is still on.

oh it is!! i hope to get there a few minutes early to let the car cool down some. maybe bring some ice to cool the plenum/intake to get real numbers that i'd see when at the track after an hour and a half rest/cool down.

But oh well, atleast it will be close and definately give me a solid baseline to see what this thing can do, and where the power is.

I'm scheduled for 3:30pm, so take 5-10 min to get the car on the dyno and setup right, then i want to let it cool some and i have about an hour to get it done. gotta be off by 5pm when they close down the shop. Sucks but they aint open on weekends cuz they go racing most of the time. I hope to get there by 3:15 and give it 20-25 min to cool. hope they only charge me for an hour still since i'm just sitting there not doing anythign with the dyno just yet

So what happened? What did it do? Numbers, numbers, numbers lol!

i made another thread on it but basically the hottest pull was my best hp at 392whp at 6250. not bad but there is more in it when it cools off. I'm thinking 400whp even

torque was flat as kansas from 3700-5000 rpms or so. 371 was peak somewhere in the 4000 range

not as much as i hoped for, especially torque but i expect my air intake to be holding me back alot

Those are some damn good numbers.

not bad i guess for an auto car but i REALLy think it has alot more in it if the exhaust is perfect and the air intake will outflow the TB which currently it wont but in a week or two i expect to have a new custom MAF setup and we'll see how it works. full 3.5" CAI

thats going from 76mm MAF stock to 89mm custom made. I should consider 95mm or 3.75" if i can find 3.75 inch pipe.

I just dont know how hard it will be to tune the new MAF setup. Tables will have to change

That I'd like to see.
Where do you intend to draw cold air from?

i got some 3.5" piping and some silicon connectors on the way. just need to decide if i want to run modded thirdgen MAF or go the expensive route and get a translator/LS1 MAF and see what happens with that.

gonna draw cold air from in front of the passenger wheel well. relocating battery to trunk


tomorrow i'm goin racing so i'll try no air filters to see how much i improve with the stock air box. if it looks like no gain, then i'll know the air box hurts performance alot. I'll do the 3.5" CAI for sure and test that. IF that dont work i'm going back to stock TPI air intake setup and using that extra space for maybe nitrous fuel cell

"gonna draw cold air from in front of the passenger wheel well."

That is exactly what I'm doing. Easy on a TransAm as the battery is located on the drivers side. Relocating the battery to the truck should also help on traction.

The MAF should adjust easier for the proper A/F ratio do to the increased airflow from no filters. The air lid is still a restiction and as you stated the 3.5" system is the ultimate way to go.

The books say one square inch of K&N filter will supply the air requirements for 4 to 4.5 horsepower with zero hp loss from restriction.
The TPI filters measure about 6x6 times 2 for 72 square inches.
72 x 4.5 = 324!
On the other hand a 14" x 3" open style element is good for 593hp. (131sq. in.)
Dosen't sound right. Or is it that there's a lot left on the table when it comes to this stuff? I see the big boys often have huge filter stacks.
Keep in mind too that your TPI intake ducting gets down to about 2.5" at the smallest point. Not much cfm there either.

yeah that doesnt sound right at all....i'm already at near 400whp with those guys. i think they flow more than you'd think or what they say. now if i take the filters out and go high 10's then well maybe an inch supports 5-6hp lol. we'll see come tomorrow

Is it possible for you to run with out the air box as well? It's been so long since I had the TPI in the car, I've forgotten if it's possible.

"i'm already at near 400whp with those guys" That dosen't mean there's not more available. A restriction will cause a hp loss. Just like our header/exhaust discussions.

ifi pull the air lid from the MAF i'll need something to hold the MAF up from hitting the serpetine belt not sure what to do about that but if i can think of somthing i could try it, but the car will be sucking hot air instead of cooler outside air

True enough.

well atleast tomorrow i'll see if the filters are more of a restriction than the TPI lid

The motor will pull more air but there will be a depression. It would be interesting to see what the pressure is inside your plenum at WOT and say 6200rpm.

I bet you are in the low 90's KPA wise. Ideal would be 100% of what the ambient atmospheric pressure is. That is what you are shooting for.

PS: This is one reason I'm redoing my cold air intake and installing an airfilter capable of 1300+cfm. No use having a 3.5" intake tube, a 1300cfm monoblade and choke it with the airfilter.

Us carbed guys look for 0" manifold pressure. My pressure starts to creep up a bit at peak demand. (AFR @ 12.7+/-) Could be looking for a little more cfm.
I use vacuum and wide band AFR guages as part of the dash instruments. It's amazing how much you can learn.

"Us carbed guys look for 0" manifold pressure"

Yes but you need a slight depression or your carb would not work. You just need to get a close as posible.

Also true.

Saw this post on David Vizard's website called GoFastNews.com. Anyways the last sentence is the money quote.

"Although our Rules state we must run a muffler, we've never used a "muffler" on the 4-cylinders. Instead, I build an 'expansion chamber' (termination box?) of DV specifications/design, which has always 'passed' the muffler rule materially. Over the last very few years, when time and $$$ permitted, we've tried a pickup-load of various manufacturer mufflers to compare to the termination box, on a chassis dyno. The only one that came near the 'box', performance-wise, was a large, single-chamber FlowMaster with centered 3" inlet and outlet. Installed backwards! And the expansion chamber/termination box design on a 4-cylinder is very nice installation-wise, within a tube chassis, because the total length of the collector/exhaust pipe is near twice the length as would be calculated for a 90-degree firing V-8 versus the 180-degree firing 4-cylinder. Termination/Expansion box's RULE !! Dave Carpenter/Las Vegas"

i dont mind pulling the filter off the track but i just hope the new setup will flow somewhat enough to make the car fun on the street. i dont want to hurt the car so bad with the filter that whenever i take it off, i gain 3-4mph and .4 seconds maybe a tenth or two and a mph is all i will allow

Maybe i should have went 4" to be sure

Termination boxes again. Saw this reply on another forum.

"I think you need to have the legal mufflers in place even with terminator boxes. In the first EMC terminator boxes before the muflers were allowed. Scott Parkhurst was running it then, but not now. I really would check and get approval in writing.

That being said, if you think out of the box you can make the mufflers act as terminator boxes as well as mufflers especially for smaller displacement engines."

Looks like they used termination boxes at the EMC at one time. The evidence keeps building that it is a very good idea.

DV has suggested the use of empty muffler cases as terminator boxes in one of his articles too.
He also says that it is possible to build a tuned system with mufflers and NO termination boxes provided the mufflers behave as open atmosphere. Apparently, there a few case style mufflers that react this way. The trick is to have the proper length of exhaust/collector in front of them.( It comes down to sufficient space again in the 3rd gen world.) Alternately, a 'glass pack' style muffler will behave as an extention of the exhaust/collector and the tuned length is the overall of the collector/exhaust and muffler. That's why I think some of the drag racers in this forum who run 'bullet' style mufflers have come across a tuned secondary length by chance. Probably something along the lines of 72" give or take. Isn't that one of the harmonics we're attempting to achieve?
----------

----------

Yes, 72" would be in the ball park.

Concievably then, the exhaust in this shot might be on the money if those collectors haven't been reduced (much) after the header and the glass packs act as extentions of the secondary.
Wouldn't that be something?

my exhaust is probly pushing well over 100 inches

Ok, here is yet another post on termination boxes. There is a key piece of information in this one. A little nugget of gold if you will.

"Allen....... if by 'loss', you mean power-wise, we did not test just a straight pipe off the collector, of the proper tuned length. Since we couldn't race that configuration. But the termination box did make more power on the chassis dyno than the best FlowMaster muffler configuration I could muster. I thought maybe the FlowMaster, installed in reverse for best flow, might = the 'box we built, because of the good FlowMaster internal volume, but the termination box increased torque and HP an average of about 4.5% combined on a 217 HP roller-cammed 2.0L Ford. And the noise level passed the test at the race track. A win-win situation all around.

I did build a not-so-scientific flow setup/tester on top of my long workbench. To flow test pipe length, the 'box, and a couple of mufflers I considered using. My test rig is where I found the FlowMaster would flow better if I reversed inlet/outlet. At least with steady-state air flow. My air flow source? I used [2] 6hp Sears-Roebuck shop-vacs, with their internal pleated paper filters removed, Y'd together off the shop-vac 'blower' outputs. That output hooked to the pipe input with smooth internal, thin metal conduit. My not-at-all-scientific output flow measuring device? I took my neat 18" x 1/16"-thick steel machnist rule and milled a 1/8" wide channel right down the middle length to within .5" of each end. Mounted the rule horizontal-lengthwise, supported by magnets, at the pipe/muffler/termination box output. With about 4' of string, I suspended a brass, pointed-end plum-bob from the ceiling. The pointed tip of the 'bob suspended into the machinist rule channel I'd cut. So....... when the shop-vac air blew through the device(s) under test, the 'bob tip would be blown along the channel I cut in the rule. When the tip reached it's max displacement with air flow, I simply took the number off the rule and recorded. Comparison measuring device only. I have no idea of the actual airflow in cfm. Oh.... I also found that using a hex-sided plum-bob at the flow outlet caused the 'bob to spin. A round 'bob essentially corrected that situation.

Some interesting, but known, findings. If a 3"-diameter piece of exhaust tubing, about 30" long, is simply cut off square on the end and flowed on my funky test rig, it flows less than if the end of the tubing is flared. And quite a bit less. That finding led me to subsequent construction technique modification of termination boxes. When I build the end plates for a 'box, I take great pains to flare the internal pipe termination of the inlet/outlet tubes. I also verified that flow improvement inside the 'box with flare/no-flare. I suspect DV also verified the findings with his 'boxes. And that's a problem with some mufflers, with good internal volume, that might be considered for a 'termination box'. Termination profile of the inlet/outlets tubes internally.

For those that may not have been there, go to Prof Blair & Associates Home Page . On the Home page, left side column at the bottom, "FREE Article Downloads". Click and read/download the article entitled "Best Bell". Pay particular attention to the 'Discharge Coefficient' changes that take place on a tube/tract when the end termination is modified correctly with a flare or bell. Many of us also know that DV, and others, have accomplished some serious experimentation in this area. And my 'country boy' findings prove them correct in every regard! -Dave-"

I read the Professor Blair article. For best performance we need to flare both the discharge and exit pipes in the exhaust termination box. DV overlooked that little nugget. The flairs were worth 4.5% horsepower in the above post.

Add that to the gain from the terminator box itself and we are talking some serious horsepower. Enough to propel a certain car into the high tens combined with another mod or two.

haha wow i really need to look at this. how much of a flare tho?

my next step on my car will be to determine the intake choke points, next will be exhaust via cutouts i think.

i was gonna do straight collector pieces but i find it hard remove entire exhaust and bolt those on, then drive to the track open headers. might as well install cutouts as they are quick and easy to test back to back on the same day at the track. open/close

sidenote: killed a 5.0 on the way home from a car show

Now you know that wasn't nice.

It seems very rare these days to find fast cars on the road. Every now and then I see a 'stang with some fat rubbers, but I'm always in the slow azz audi.

But then on the other hand, I know that when I DO take out my car, I can't think of any car around here that it won't wipe up.

he was pacing me, i had to do it car wasnt that slow either.. probly high 12's from the way it hung with me at first. sounded stock it wasnt making noise at all but then again i cant hear much over my car quick 50 roll to about 75-80. didnt take long for me to start pulling so i ended early

I would hope so!

[quote=Batass;3853148]It seems very rare these days to find fast cars on the road. Every now and then I see a 'stang with some fat rubbers, but I'm always in the slow azz audi.

It's the opposite over here. It seems like every one was given a stang for a birthday gift and was told it's the fastest car on the street.

Sounds like I need to move out of Amish country.

I see all the fast cars when mine is busted and sitting in the shop!
Two really nice 3rd gen Camaros have popped up out of nowhere. They're too quiet to be really quick but my service truck wouldn't take them.