best airbox/filter set up?

[Gary Williams]

Just found this interesting thread. Over the past 20 years my 1967 GTV has used the stock air intake, a Sprint system as shown in this thread, and a one-piece Pipercross setup. I have dyno tested the stock intake versus the Sprint system. The Sprint made 5 hp over stock, and sounded great doing it. The sound part is a matter of taste; the horsepower gain with the Sprint was real.

Recently, when I swapped from 1750 engine to a 2 liter (after previously changing out the original 1600), I foolishly bought a Pipercross air filter and backing plate. I am now awaiting an ITG filter to take its place.

Here's why I say "foolishly" regarding the Pipercross purchase. The air filter keeps out large rocks, but not normal crud found in urban and/or suburban air. The backing plate is too thin to hold the carbs firmly, so, even with the stock strut down to the block, the front carb moves independent of the back carb. This means that the car will not idle properly; you can actually watch the linkage move around. I am having a new, thicker backing plate fabricated.

Pipercross is not interested in feedback, nor is the company interested in making good on defective parts. I was reminded of this when looking at the red ram pipes shown in one of the photos in this thread; they are from Pipercross, not TWM. I have a set of Pipercross ram pipes. The mounting holes don't fit my Weber DCOE 45's because they were manufactured incorrectly. When Poopercross declined to take them back or exchange them, I went to TWM. You can see pictures of my TWM ram pipes on this web page, http://greend.com/new_page_3.htm, or on TWM's website.

If you're wondering why I didn't stick with the old Sprint setup on the new engine, it's because mine are for DCOE 40's. Didn't want to hog them out to match the 45's. Besides, the TWM ram pipes were just too cool.

Finally, I've heard from Alfisti with far more experience than me, that the Webers like one big air cleaner over individual sox or filters. Some of the comments in this thread seem to reinforce that belief.

If I were going to do it all over again with the new engine, and that may yet happen, I think a GTA-style airbox is the way to go, with a good filter on the front end.

[borrani]

Gary,

That is one beautiful engine, and engine bay. Thanks for your insight.

Tell us about the dual brake reservoirs. Have you converted to a dual master circuit, or a juice clutch?

Steve S.

[Gary Williams]

When we installed the 2 liter motor we also put in a late model tranny. That meant we had to do something to make the clutch work. I chose to put in a 1969 pedal box and hydraulic clutch. My friend Richard found a simpler solution to make the same engine-tranny swap in his '67 GTV. From Alfaholics.com he bought an alumimun flywheel that let him use his manual clutch and a stock clutch.

[CarPoor]

Gary-
Beautiful! Love it!

[borrani]

Gary,

But, you now have a much safer vehicle with the dual circuit braking system.

Steve S.

[SeekGTV]

I just found this thread and I though I'd post a picture of my upgraded air filters. Standard K&N equipment replaces the old alum, plenium and large black canister air box.
Yes, I kept all the old parts in case the next owner wants to go back to the original.

[Sprintn]

Gary,
That is a beautiful engine and carb set up!!!! And your engine bay looks like it was completely rebuilt and reconfigured!?
Also... I'm curious to know how many horses you estimate that your new engine set up is puting out.?
Enjoy!

Sprintn

[borrani]

Yes, it is beautiful! When you want some extra hp, you can even put that original airbox back on!
The gen'l consensus is the carb mouths like to have a large plenum area around them, not the little filters. These little filters are also breathing hotter underhood air, no ducting for fresh air. Even a small velocity stack is said to aid flow, as the intake is a little short on the Alfa motors.

Respectfully,

Steve S.

[Gary Williams]

We dyno'd it a few weeks ago at 127hp (rear wheels) on pump gas. That converts to about 153 at the flywheel. Not what I was hoping for. We had several problems:
1. The dyno didn't like my Marelli Plex 201 electronic ignition and kept shutting down. We got only one full run to 6500 rpm in an hour.
2. The dyno operator kept hearing pinging, and had me retard the ignition to eliminate it. Turns out the Plex 201 was going to full advance at 2000 rpm; that's what caused the pinging. He had me retard the ignition to about 30 degrees. More advance would have given more horsepower. I've just switched to a Centerline electronic ignition.
3. The crappy Pipercross air filter setup allows the carbs to flex, which throws of their synchronization -- they are never in tune. This is being changed right now, to a custom backing plate and an ITG filter. Also, we should have taken the air filter off to let the ram pipes breath.
4. Because of the dyno problems, we never got the jetting sorted completely and were running way rich in the mid range, right where we should have seen our best torque. With fuel washing the cylinders, that also meant lost horsepower on the brief run up to 6500 rpm.
5. And worst of all, my new engine is drinking a quart of oil every 200 miles. That means horsepower is lost as compression blows past the rings. Seating new rings is not always a slam dunk, we find, especially if your new DCOE carbs come with internal problems that keep the engine from running properly during that critical time when it is run for the first time. All this is making a new Corvette sound mighty tempting right now.

[Gary Williams]

I'm confused here. Not sure who is referring to what. Gary and SeekGTV are two different people, with two different engines. My car (Gary's) is at www.greend.com. It uses a one-piece air filter because I too have been told by the wizards that the Webers like the large plenum area. My engine has 1.5" TWM Induction ram pipes.

[Sprintn]

Or... I believe, TWM Induction also has airboxes that plum towards the grill that you can then stick a nice large K&N or Powerstack filter at the end.

Sprintn

[Sprintn]

Yes Gary... I'm speaking of your engine with the cool TWM air horns. Like I mentioned above. I think TWM also has air boxes that have an intake directed towards the front grill that a cylindrical air filter can then mate to. THis way, like Borrani said, your engine can try to pull from some cooler and more dense air coming through the grill.?.?

Like I said befor... that is a Model Engine and engine Bay you have there!!!

Sprintn

PS... Does this thing have a spellcheck????

[ColoradoSpider]

Some things to remember about filters/air boxes. Its not just filter area which is important but also air box size and air temp. K&N filters (the type that clamp to each carb/intake runner eliminating the air box) wont necesarily help performance. On a car with a closed hood they tend to suck hot air which kills performance. They also probably wont have as much filter area as a stock Alfa element. Air box volume also plays a big part in engine tuning, much as exhaust length and size does. I dont know if the original Alfa designs were as good as they could be but I doubt much (anything) will be gained by dumping the stock air box and installing smaller than stock filters. One worthwhile mod though may be to set up some sort of cold air system. I removed the air horn off my stock box and replaced it with a large flex pipe that is routed to the side of the radiator where there is an air port open to the front of the car and cold air. I've seen a few different setups and I think Alfa did something like this at some point too.

Ed

[Trav]

Back before the BB made so many options and opinions available I had to solve the air box problem. The PO had converted to carbs with little square foam filter boxes. I put curved velocity stacks on and built a filter assembly. I found a likely candidate in the K&N catalog and cut top and bottom plates from aluminum. It provides lots of filter area and is better than foam socks.

[genericwood]

I'm curious where you found the curved air horns? I have been looking for some to fit 45mm carbs.

Erik