V-8 Weber dual plenum induction

By all means the pulsing helps, but you've got to factor in the lag time of the distance that the air has to travel.

And air that is headed toward a dead air zone is going to slow down as it encounters resistance. Likewise, if a carb on the right side is drawing in an intake pulse before a carb on the left side has *finished* drawing in a full gulp, then the right carb will steal some of the air that would have better been used by the left...in a dead air setup.

You could get rid of the dead air either by opening up the left side of each plenum, or by removing the plenum and going with an air filter wrapped around each set of carb twins (side draw filter).

Either of the above solutions should give you a more optimum air/fuel mixture, especially in the left side carbs.

 

The swiss-air idea still has a left side dead air zone with the lid on.
Image Unavailable, Please Login

 

Your dual side intake 308 box should work (if you can figure out the plumbing, of course).
Image Unavailable, Please Login

 

Russ,

Nice photoshop technique. It fooled ME!

Not to criticize, I like your design, but if you wanted to you COULD replace the oil to air cooler with an oil to water cooler to take some advantage of the left air intake. As far as I"m concerned, the stock oil cooler is just an engine compartment heater-upper. On my GTB it was blowing at the oil tank. That makes a lot of sense. Cool the oil and then warm it up again before going back to the engine!

On the other hand, this is how I got on my treadmill 308 project. Every mod leads to another one.

Wil

 

Will,

Could you give us the Mfrg part number and more details on the cooler/exchanger?? I am seriously thinking about doing this, rather than going the thermostat route.

As a side benefit, the filter could be moved in line and a dual snout air cleaner, or dual box unit could be installed.

thanks,
chris

 

Chris,

I'm not being a wise guy here. Didn't you receive my answer to your PM on the oil cooler subject?

Unfortunately, I pitched the box from the (oil to water) oil cooler and have no idea where the invoice might be at this point. If you go to the Setrab web-site you'll find the phone number for Setrab ( I think they're in California). Tell them you want their largest model and you need it with AN16 oil line fittings.

I think by "filter" you mean the OIL filter? I have my 308s filter relocated because the supercharger/intake manifold needed the space occupied by the oil filter. Unfortunately you have to MAKE a manifold to adapt oil hoses from the oil inlet and outlet on top of the engine block. You can't just buy one although if you could spare the room you could leave the OEM cast aluminum oil filter adaptor and try to adapt a commercially available block-off plate for a Chevy, Ford, Nissan, etc. I have another car with a Maserati V8 and a Nissan block-off plate fits the oil filter mount perfectly so that I can remote mount the filter (double Fram HP1).

Wil

 

Thanks Wil,

I cruised through the "Bulk" email inbox this morning and found your response, I will give Setrab a call and look into the block off plate possibilities.

best,
chris

 

amazing work Russ...

edit : by the way, what sort of numbers a in the "ok" zone for a stock 79 308 GTS with the LM-1. i have been helping a friend sort out his car, and the numbers get confusing.

 

excellent info !!!! Jfrazar on here owns both the car and the LM-1 i have been using, we are both still learning what its telling us. i will let him know about this thread and see if he can post our notes. all of my notes are at his house, 30 minutes away. i also noticed a mid throttle rich condition, with the car seeming to be lean a bit at idle. he is running 60 /125 /200 with individual aircleaners and Crane x700s. we are thinking the 60s are too big, which is why he is running so rich in the progression and mid range. i am set on 55 /135 / and then tweaking the air correctors between 190 -220 depending on seasonal weather and driving use. i think his lean main jet is allowing the plugs to clean up and make up for the fat idle jet. i really dont like the 60s for around town street car driving as there is little chance to clean off the plugs without getting harassed by cops . he does blow some carbon / rich fouling out now and then, and has a mid range pop from some of the intakes thru the carbs. we are trying to get that last few % out of the car as it runs *almost* perfect and we are shooting for *perfect* !!

my 911 with the Motronic has been fun to learn on. i may keep the 911 awhile , but i am now on the market for a early carb 308 or euro spec Jalpa early Lambo of some sort. no 12 cylinders for me yet... cant justify the expense!


i would love to join you in a seperate thread on a/f ratio numbers, perhaps Brian, the current owner of my old GTB will allow us to get some numbers of a points carb car with the open air cleaners, versus Joes with the later emissions cams ect. Joe has a mechanic that is a genius with old ferrari airconditioning systems, and the load the a/c places on the car noticablely changes the a/f numbers. the a/c in his 79 308 will freeze you out of the car with the mods thay have come up with. my old GTB is supposed to be getting re fitted as well, and we can post the swings in the a/f numbers.

Michael ..... currently ferrari and carb car-less!!!!!!!!

 

Back in the older thread on gutting the carb 308 airbox, when this dual plenum subject was first being broached, it was questioned as to what a wall down the middle (left to right, seperating the front and rear carbs) of a stock aircleaner housing would provide. I can appreciate that it would NOT be anywhere near close to what you have built for your car in any performance gain, but what would the consensus be that it would provide some benifit, considering that the airbox in question has had its sound deadening guts removed.

Or, what of possible baffles between all four carbs, a sort of X pattern, forcing the carbs to drink from thier own part of the airbox?

 

Russ~

In your dyno pulls with and without the airbox, did you ever run the box without the aircleaner element? It seems, looking at the box, Ferrari was simply trying to "make it fit", and didnt concern themselves a great deal with how restrictive it was. While you are not familiar with the GT/4/B/S, I am also not familiar with a GT/4 or a Mondial. But the GTB I have is very constrained for space. The neck from the airbox goes directly into the airbox from the tube from the fender port. It may be possible to run the airbox into a pipe and fit a K&N cone filter that sits up in the pillar/flying buttress area. I could try to remove the air tube and simply allow air from the fender port to feed the space in the area of the K&N. I will go take a look, this may prove to be quite simple.