03-04 Cobra Plenum

Give your 03-04 Cobra a boost in horsepower and efficiency!

Plenum port and polish exchange service.

 

 

This auction is for the exchange of your intake plenum for a ported and polished unit.

We require a functioning core for all our work and have two options for your convenience.

You can send your original Plenum to us, and upon receipt, I will mail out the ported version 

OR

You can pay us a refundable core deposit of 79$ which will be returned through PayPal after you ship your original throttle body back within 31 days.

After payment is received for the eBay auction I will assume you would like to take advantage of the core deposit unless otherwise noted. I will send an invoice through PayPal to that same e-mail address and ship out the item when I receive payment.

Also please message me if you would like information on custom porting work for any application!

When you are looking to improve the efficiency and performance of your engine one of the best ways to think about it is like a big air pump. The more air you can move in and get out the more efficient and powerful your engine will be. The problem is that through every part of your engine there are restrictions that rob that power.

 

The stock plenum has a number of areas that can kill flow. Looking at the throttle body side there are two obvious protrusions right in the way or air flow. Ford cast in large bumps for the IAC to thread into. They are even worse since they are very close to the throttle blades restricting flow, so they are cut off and ground smooth. There is still plenty of material for the bolts to thread into. For optimum airflow I suggest trimming your bolts and using some thread locker so they are flush with the bottom on the plenum. 

Looking through both sides of the plenum you can where ford designed bolt access reliefs that cut into the smooth interior flow. These are ground down to minimize the intrusion into the airflow. You can also see the better merging of the airflow after the throttle blades. 

On both the front and the back the openings are enlarged to match the gasket. This is especially important on the back where the opening is enlarged considerably and reshaped to the correct uninterrupted oval. You can see the gasket line in this picture and how much material is removed. 

 

 

When all of that work is done we polish the inside surface to a mirror shine by gradually using finer and finer grits so the air doesn’t hit any bumps that would cause turbulence. If you would like another color message us and we can accommodate for an extra 10$. If you have one of the large single blade throttle bodies or a larger dual plate one, message me and I can match the front opening for either for an extra charge. 

People usually report about the same seat of the pants power increase as a cold air intake or free flow exhaust. Your performance gain will also depend on how modified the rest of the car is, if you have upped the boost this will really let your cobra breath! The more you have done the more your throttle body will be a bottle neck and the more opening it up will help. The computer usually takes a bit to adapt to the increased flow just as with any other bolt on modification.

These Plenums are 149$ shipped in the continental US vis USPS priority mail. Shipping abroad or expedited shipping? Just ask for a quote. We also do custom porting and polishing for almost any car! Send us a message for details!