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Discussion Starter #1
So I decided to start a little project mostly for fun and curiosity. Now before anyone says it, I read through all (I think) the old threads and the reoccurring comment is that the original Spica air box is very well designed and will offer the best performance for you engine. I agree with this but I also like to experiment.

So considering I will never race my Alfa, or have a need to put it on a dyno, or care if I loose 6 hp at 5000 rpm, the goal of this experiment is to see if I could improve the intake sound of my car without any adverse effects, not make any non reversible modifications to the car, and to document the process in case someone else wanted to do the same.

So here it goes:

Car: 1969 US spec 1750 Spider.

I purchased 4 Kinsler velocity stacks. Here is a link to them:


1655750


They are 6” long and from what I have read, this is the optimum length for the 1750.

If they are installed directly on the throttle bodies, the last two closest to the firewall, will hit the bodywork. The options are to trim the bottom of the bell or the cut the stack short. Since the velocity stacks are very expensive, I did’t want to cut them. I came up with the idea of using a 45 degree elbow to raise the stacks away from the bodywork.

I ordered from Amazon, 4 Ronteix 45 degree elbow 2” ID on one side, 1.75” ID on the other. This fit over the throttle body and allowed the stack to fit inside. The elbow is too long so both sides need to be cut shorter.
1655751

1655752

1655753

1655755



I used simple worm gear clamps to test fit everything and will eventually change to T-Bolt clamps.

One thing to note is that with the elbow, the overall length of the stack is more than 6”. If everything works out, I may eventually trim the stacks to try to get back to the 6”.

Here is a pic of the stacks installed.
1655757


I thought the flexible elbows would too flexible and allow the stacks to hit but in fact they are quite stiff and once clamped down, they stay in place.

I ordered 4 filters from PJ Motorsports. Their standard filter is for a 3” dia bell but the Kinsler bell measured 3.15”. They gladly custom made a set for me. I also purchased a set of prefilters from them which I think I will always use. They were very helpful and a pleasure to deal with.

Here is a link to their site:


Here is a pic of the filters installed.
1655758


I still have to figure out how to filter the air going into the idle air boxes. I’m thinking of tie strapping a foam filter to the backside.

I hope this will help anyone who is interested in trying out velocity stacks.

By the way, I have a video but I cannot figure out how to post it.
 

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Looks really nice! For video, upload to youtube and then just post a link to the youtube video. would love to hear it.

Also, you might know this, but Shankle made a complete kit that was velocity stacks with uni filters that mount on top. I have them on my car and they work well. Personally i felt a small improvement in top end power and didn't notice a low end decline. I'm pretty sentitive and realistic to these things. Found a set new on ebay.
 

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Looked awesome until you put those filters on :eek: ... you could even make things better by having the clamp part of the hose clips underneath, hiding them.

Have a look at the filters Alfaholics use, far better looking IM humble O
Pete
 

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Discussion Starter #5
Looked awesome until you put those filters on :eek: ... you could even make things better by having the clamp part of the hose clips underneath, hiding them.

Have a look at the filters Alfaholics use, far better looking IM humble O
Pete
The clamps are only temporary, they will be hidden when done.
The Alfaholics screens look awesome but I don’t think they offer much in terms of filtering ( if we’re taking about the same ones). I wanted something that was more functional.
 

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Discussion Starter #6
Looks really nice! For video, upload to youtube and then just post a link to the youtube video. would love to hear it.

Also, you might know this, but Shankle made a complete kit that was velocity stacks with uni filters that mount on top. I have them on my car and they work well. Personally i felt a small improvement in top end power and didn't notice a low end decline. I'm pretty sentitive and realistic to these things. Found a set new on ebay.
Thanks, I’ll try your suggestion.

I’ve been looking for a Shakle system but haven’t had much luck.
 

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The clamps are only temporary, they will be hidden when done.
The Alfaholics screens look awesome but I don’t think they offer much in terms of filtering ( if we’re taking about the same ones). I wanted something that was more functional.
I meant this type of filter. Just about all race car use them

Pete
 

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Discussion Starter #10
I just like this photo.

What you need is a clear perspex airbox to go over the ends of those sexy air horns and have an air cleaner separately somewhere :)
Pete
You have just given me a great winter project idea!
 

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So I decided to start a little project mostly for fun and curiosity. Now before anyone says it, I read through all (I think) the old threads and the reoccurring comment is that the original Spica air box is very well designed and will offer the best performance for you engine. I agree with this but I also like to experiment.

So considering I will never race my Alfa, or have a need to put it on a dyno, or care if I loose 6 hp at 5000 rpm, the goal of this experiment is to see if I could improve the intake sound of my car without any adverse effects, not make any non reversible modifications to the car, and to document the process in case someone else wanted to do the same.

So here it goes:

Car: 1969 US spec 1750 Spider.

I purchased 4 Kinsler velocity stacks. Here is a link to them:


View attachment 1655750

They are 6” long and from what I have read, this is the optimum length for the 1750.

If they are installed directly on the throttle bodies, the last two closest to the firewall, will hit the bodywork. The options are to trim the bottom of the bell or the cut the stack short. Since the velocity stacks are very expensive, I did’t want to cut them. I came up with the idea of using a 45 degree elbow to raise the stacks away from the bodywork.

I ordered from Amazon, 4 Ronteix 45 degree elbow 2” ID on one side, 1.75” ID on the other. This fit over the throttle body and allowed the stack to fit inside. The elbow is too long so both sides need to be cut shorter.
View attachment 1655751
View attachment 1655752
View attachment 1655753
View attachment 1655755


I used simple worm gear clamps to test fit everything and will eventually change to T-Bolt clamps.

One thing to note is that with the elbow, the overall length of the stack is more than 6”. If everything works out, I may eventually trim the stacks to try to get back to the 6”.

Here is a pic of the stacks installed.
View attachment 1655757

I thought the flexible elbows would too flexible and allow the stacks to hit but in fact they are quite stiff and once clamped down, they stay in place.

I ordered 4 filters from PJ Motorsports. Their standard filter is for a 3” dia bell but the Kinsler bell measured 3.15”. They gladly custom made a set for me. I also purchased a set of prefilters from them which I think I will always use. They were very helpful and a pleasure to deal with.

Here is a link to their site:


Here is a pic of the filters installed.
View attachment 1655758

I still have to figure out how to filter the air going into the idle air boxes. I’m thinking of tie strapping a foam filter to the backside.

I hope this will help anyone who is interested in trying out velocity stacks.

By the way, I have a video but I cannot figure out how to post it.
Beautiful trumpets! And a really nice motor and engine compartment!
 

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Here's my installation after recommendation by Wes Ingram: "6 inch Kinsler ram tubes attach directly to the Spica Throttle bodies. The velocity ram tubes increase power and torque over the hard to beat factory air box"

I installed the air horns directly onto the throttle bodies and duplicated his scheme to create an open-top air box that is closed when the hood is down.

Finally, yeads ago I did a back-to-back chassis dyno test of the Shankle Quadra Flow intake vs. the stock SPICA air box and the SPICA box was better except for a very small 2 +/- HP increase around 4000 - 4200 RPM.

Edit: The earlier Shankle setup changed the sound, but the air horn sound is louder


1655880
1655881
.
 

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Discussion Starter #15
Here's my installation after recommendation by Wes Ingram: "6 inch Kinsler ram tubes attach directly to the Spica Throttle bodies. The velocity ram tubes increase power and torque over the hard to beat factory air box"

I installed the air horns directly onto the throttle bodies and duplicated his scheme to create an open-top air box that is closed when the hood is down.

Finally, yeads ago I did a back-to-back chassis dyno test of the Shankle Quadra Flow intake vs. the stock SPICA air box and the SPICA box was better except for a very small 2 +/- HP increase around 4000 - 4200 RPM.

Edit: The earlier Shankle setup changed the sound, but the air horn sound is louder
You’ve posted a lot about the subject in several threads and they were an inspiration for my project. Your setup is very nice!
 

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Discussion Starter #18
Update:
I got a chance to take it for a test drive and boy is it loud. The intake growl is now louder than the exhaust, but it sounds great. I think this is something that I could live with since the car is only driven occasionally.
Drivability seems to be the same as with the stock air box. Other than the sound, I haven’t noticed any difference. The mesh filters only slightly muffle the sound but I think they are necessary if driving on the road.

Need to decide if the horns would look better pointed forward, pointed backwards, or vertical as currently setup.
 
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