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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:
![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.
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:
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.
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.
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.
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.
... you could even make things better by having the clamp part of the hose clips underneath, hiding them.
