dynoed the fb, big letdown
 

so i have an 83 gsl, 13b 6 port swap
mods

stock port 175+k
gsl-se fueltank, pump, lines
weber 48dco carb (60f9 idle jets, 175 primaries, 160 air bleeds)
holley regulator
rb collected header and presilencer, 2.25 custom presilencer back with magnaflow
s4 lower intake manifold
no port sleeves

car made 123.8 hp ande 117.3 tq

must say im not happy with those numbers but theres room for improvement

We can get that motor running. Head out on the highway and look for adventure!

Wheel HP?........sounds about right,roughly 140 crank HP.

Hard to improve on EFI for nice round HP numbers.Carb might do better on the topend,but then again you've got stock ports.....

You might have done a lil better on the bottom end with working AUX ports.

yes thats rwhp

rear whel Horse power.

That's about normal for that motor

not shooting for low end power,
also my power dove after 6400rpms
ill get a scan of the dyno sheet tomorrow

im basing this off a friends setup which was practically identical and made 140whp and he was running a 45mm

Just a guess from me, but maybe you got to much carb. Ive never really messed with them on a rotary though.

also my friend made his peak hp an tq at the same spots i made mine at
peak hp 6400 peak tq 5200

well i thought that to, im sure this carb would perfom better on a street port or 1/2 bridge motor
but my engine is breathing the most it possibly can for being stock port

Nah the 48 should make more power!

why did you remove the port sleeves? from my understanding it fucks up the flow when you do that...witch makes the motor not flow as well...the whole is bigger but it does not move as much CFM

Like I said it was just a guess. Kinda like how 3 2barrels make more power than 2 4barrels.

Where did you hear that? I've never heard that! I've never seen any car run 3 2barrel carbs. when Chevy guys go huge they do 2 4barrels. not 3 2 barrels. And running w/o the sleves is way better. Just look at my dyno sheets. No loss of TQ or flow.

I heard it a long long time ago. Basically it has to do something with the air velocity, and that the 3 2barrels have more than the 2 4barrels. Some of the old pontiacs came this way and they were the most looked for models. Whether it is accually true or not I am not sure. I could always try and find that book that had it in it and scan up the pages.

Makes sense I guess, but I guess most 2 4barrel cars are charged. and we've officially stolen this thread. gr8... Well I think the big problem is tuneing and intake manifold, but that's something I'll remody this weekend. hey Rotorsex you should come over some time this weekend and we will get this taken care of.

Oh yeah. I apologize about the quick thread stealing.

meh, it keeps it at the top. gnite... LOL!!!

hyper, youve never seen the weber "6 packs" back in the 70s on the v8s those were the shit, not as common and redneck as a 4bbl more unique and defniatley more expensive. hahaha

ill come up, prolly tuesday or next weekend, dont get payed till monday and im dead broke :(

My '73 Z had three 2 barrels and hauled ass. Anyway....

Take a good look into your ignition. There is a lot of power to be had there. Check out the 2nd gen coil/transistor trick setup. This made a huge difference in my car, especially at the higher rpms. Normally my car would start to die off around 7k, but after the upgrade she would pull hard to 8k and beyond. Might go further than that too, but I never tried and don't want to blow my motor.

any vacume leaks? or does it run rich with an se pump?


Stock ignition? e fan?

The multicarb setups used in the early 60's Pontiacs, Olds, etc. were to compensate for the lack of a big four barrel carb. Holley didn't come out with the larger 600 cfm and up models in production cars until the real "muscle car" era kicked in. The odd shape of the runners in the multicarb manifolds make tuning notoriously difficult. They do help intake velocity at lower rpms because just one of the small dueces functions as the primary circuit, while the other two function as large secondaries. The six pack cars were more of a marketing gimmick than a real power producer. Swapping the 3 deuces for a single large four barrel is usually worth some power.

A large single barrel almost ALWAYS outperforms multiple carb setups in V8 applications. The design of the intake manifold dictates this.

Kev

Disappointed? That's really good for an essentially stock engine. Using a carb is hurting you a bit, and having no sleeves is *definitely* hurting you.

You should study the voltage drop off on your dyno chart. Stock ignition drops off bad over 6000. Do some direct fire action. Its cheap and will probably give you slightly better numbers. A lot of fuel/air mix is cool, but you gotta have some way to burn it!

PJ you're wrong I did 140rwhp with a carb and no sleves. People need to stop parrotring bad info.

what size venturies are you using

The stock aux port sleeves will help a little, not much, the Pineapple ones will give better laminar flow into the housing. It looks to me that the torque drops off a little too quick. Most of the dyno sheets I've seen, the torque curve stays pretty flat once peak is reached, then a quick drop when air flow is maxed.

The 64 to 6? GTOs had a 3 duece setup for carbs, Really sweet and made better power than the 4 barrel, better fuel economy too if you stayed out of the secondary pair. An origininal setup is high dollar. Then there is the 440 GTX 6 Pack. I pulled up next to one in the early 70's in my Road Runner. I reved to 5k and couldn't even hear my car over his idle, he had a very scary car that had been built with a huge cam.

My only experience with a 6 pack is on an old ladies car. Her son went into the army and removed 2 of the carbs so she could handle it or something like that. She had regular tune ups at the garage I worked at. It came in one day done a PM, and didnt notice that her son got back and put the other two carbs back on. Lets just say when I mashed down on it to cross the street to get to customer parking it was the ride o my life.

Somehow I have grave doubts, unless there's something you're not telling.

Did you ever take it to the track? MPH vs. weight is the best power indicator, chassis dynos are really none too accurate.

Yes you do, runing no sleeves is pointless crap and screws the air velocity VE all up. Go study some. Oh yea and the port timing is now hog wash. With a carb the port timing design of that motor is void anyhow.

Why would not having sleeves hurt top end performance? They'd be open at full throttle anyway. If anything, removing sleeves has increased the size of the port and improved high rpm flow.

[QUOTE=trochoid] the Pineapple ones will give better laminar flow into the housing. QUOTE]

You don't really know what "laminar flow" means, do you?

It does not increase the port removing them, it makes them more like a bottle design instead of a steady flow rate despite the 90deg radius.

[QUOTE=purple82]Actually I do know what laminar flow is and had I not changed majors in college so many times, you would be calling be Dr. or Professor trochoid. :rlaugh: I have studied fluid dynamics, and gases are concidered fluids.

At the end of the aux ports is a 90* turn, that's like running into a brick wall, backing up, then deciding to turn right or left, at the same time backing up all of the traffic behind you. Not very efficient for air flow.

I would see what size chokes are in that carb. Smaller than 38mm and they would really be choking the engine at the top end. With the size jets you have, if its getting enough fuel at the bottom end, I'll bet you have small chokes. It would be real drivable on the street though, give me more power over a wide range down low over a dyno queen(just a high HP number somewhere up top) anyday.

You should be able to see the size by looking into the carb at the venturis. There will be little numbers cast in the top near the edge.

If that's true then you'd know that the bulk flow into the port is laminar or turbulent based mainly on it's speed.

You'd also know that the outside corner of a flow bend is where the slowest flow is occuring, counter to solid body motion, and that adding a wedge to that outer corner does next to nothing for airflow impedance.

I'm not sure what you're trying to describe. The sleeves are straight and when you pull them out, the remaining port is straight.

When you pull them out it creates an over hang so something like [ ]. I really whish I had a scanner right now. To explain my thoughts on the sleeves themselves. I am sure you understand purple how the wedge can lower the VE and increase the velocity. But this is only if the area radius of the sleeve is still greater or up to -20% of the area from the selves to the opening circumference.

Like I said I need a paper to make a diagram.

Wow, this is cool! :) To think that such a simple question turned into such an educational and entertaining thread!

Oh yeah, and I'm watching the spelling too guys.

Trochoid; you mispelled considered! Shame on you!

:jump:

If the aux port was a smooth raduis bend on both sides, then the cross sectional area of higher velocity flow would increase in size. With the 90* bend, the turbulence at the 'L' reduces clean flow on that side of the cross sectional area.

In a round, straight pipe, if one draws a line through the center, and a standard bell curve underneath it, that will show the relationship of velocity to that part of the pipe. When a bend is intoduced into the flow, the top of the bell curve, higher velocity, the bell curve becomes skewed to the the outside or longer side of the bend.

Solids and liqiuds, in dynamic applications, have the same flow characteristics, except that gases are compressible. Since we are dealing with a gas here, the 'L' corner will cause more turbulence and interference with flow than a liquid would because the liquid will not 'push back' like a gas will and acts as a solid, somewhat smoothing the 'L' into a curve, negating the turbulence conciderations.

Keep in mind that intake gases work under vacuum and not pressure and some of the dynamics are variant.

I Googled concidered and apparantly I have been mis-spelling it for years. LOL :dunce:

Man, this is awesome. But nobody will ever find this incredible debate due to the fact that it is buried in the depths of a very commonly titled thread. :( A wealth of information lost forever.

This discussion is surely worthy of its own thread. I have to go to bed now due to weird working hours and my drunken state, but I will be checking back in on you guys later tonight.

Oh, and Trochoid; it's "gasses". :) Tsk, Tsk...

lmao! we were typing @ the same time...

My spelling is usually pretty decent, my typing sucks, where the hell is the spell check. You are just what I need, a proof reader.

well my 123 WHEEL hp is a huge increase over the gsl-se's stock 135 to the FLYWHEEL. so i wouldnt say having a carb is hurting me at all. im going to order some pineapple sleeves and pin them open for a smoother flow into the 6 ports, also am going to look into some second gen direct fire.

since that dyno run ive upped my air corrector jets to 220 so im running 175 primaries and 220 correctors, i have also advanced my timing 5 degrees over stock, it seems a bit peppier. we will see how it really goes after i install the DF and the pineapple sleeves.

When you get the sleeves, epoxy them in place so they won't rotate, unless you plan on having the work like stock.

If you had a wide band O2, it may help things.
My 12a BP sucked with a carb, went to EFI & a lot more fuel, I'm up at 204 rwhp.
So I think Fuel.

Everyone can argue all they want, but it's hard to win an arguement against physics.

Here's a CFD simulation that I just ran. Notice that the high speed and low pressure is on the inside of the bend. The high pressure and low speed is at the outside. Suprised? Like I said, it's counter-intuitive until you understand what's going on within the fluid.