1989GTATransAm

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.

Orr89RocZ

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

skinny z

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.

skinny z

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.

Orr89RocZ

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

skinny z

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


QUOTE]

Mr Moroso says 410 rwhp then!
Good luck.

TheBadazz

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.

1989GTATransAm

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

skinny z

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!).

TheBadazz

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.

Orr89RocZ

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

1989GTATransAm

"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.

skinny z

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?

Orr89RocZ

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

1989GTATransAm

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

Orr89RocZ

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

TheBadazz

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

Orr89RocZ

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

TheBadazz

Those are some damn good numbers.

Orr89RocZ

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

skinny z

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

Orr89RocZ

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

1989GTATransAm

"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.

skinny z

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.

Orr89RocZ

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

skinny z