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Cosworth 1.5 Bar High Pressure Radiator Cap (Part Number: )
Cosworth 1.5 Bar High Pressure Radiator Cap (Part Number: )
Cosworth 1.5 Bar High Pressure Radiator Cap (Part Number: )
Cosworth 1.5 Bar High Pressure Radiator Cap (Part Number: )
Cosworth 1.5 Bar High Pressure Radiator Cap
Read 6 Reviews | 5 Q&As
Part # 20027842
msrp: $39.00

In stock! Ships same day
Universal part

Features & Product Details

Cosworth High-Pressure Radiator caps are engineered to increase the boiling point in your vehicles cooling system providing improved cooling efficiency. Each cap is manufactured from heavy gauge stainless steel with a race proven high-pressure valve. The Cosworth High-Pressure Radiator Cap is an essential part of an upgraded cooling system and will help to safely maximize engine performance by controlling the engine temperature at an optimum level. Available in 3 pressure ratings.

Application: Most Subaru, Nissan, Mitsubishi Lancer Evolution vehicles and early Honda (EG/DC) as well as pre-1995 Toyota applications.

Note that this cap will not fit the BRZ/FR-S twins.


Brand: Cosworth
Opening Point: 1.5 Bar
Mfgr. Warranty: 1 Year
Condition: New Product
Return Policy:

RallySport Guarantee - 30 Days

Items that are covered under the RallySport Guarantee offer a 30 day no questions asked return policy.

RallySport Guarantee items may be returned within 30 days of the original invoice date and must include all the original parts and contents for a refund.

The RallySport Guarantee does not apply to products that have been modified, damaged, misused or abused. All returns require an RMA (Return Merchandise Authorization) Number, and freight charges are strictly non-refundable. For more information regarding our freight refund policy, please refer to our return policy page found HERE.



6 Reviews
4.3 out of 5 Stars
5 Stars
4 Stars
3 Stars
2 Stars
1 Stars
Customer Photos and Videos
No user media. You can upload a photo or video of your install by posting a review.
Fell apart after a week  6 years ago
1out of 5stars

Fell apart and caused my engine to over heat. Nothing is better than OEM caps
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cosworth 7 years ago
5out of 5stars

if installing on sti you need to purchase 2 but i havent seen any noticeable difference and just like stock caps they have the 1.3bar on the radiator and 1.1bar on the secondary filler area so i just staggered 1.5bar and 1.3bar
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Good 7 years ago
5out of 5stars

Useful item, engine feels better, worth buying, especially with RSD's great customer service and support
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Good to Go 7 years ago
5out of 5stars

It fits and ships fast!!
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1.5 oh yeah 7 years ago
5out of 5stars

Just need to upgrade my radiator before using this puppy. Thanks Rally Sports Direct for the speedy service and delivery all the way to Australia. It took less than 4 days to arrive from the time I placing the order.
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  • Q: Radiator cap  Alex.2 years ago

    If I buy this cosworth 1.5 bar radiator cap will I have to put the same one on the high side? Or could I use a 1.3 bar for the other one?
    • 0 of 0 people found the following answer helpful

      A:  You will either need to match, or have a higher rated pressure cap then what your system is rated for. IE, if you have a 1.3 bar system you will need to AT LEAST have 1.3 or higher.

      Tyler A. @ RallySport Direct 2 years ago  
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  • Q: How does this work with a 2 cap system?  B double U3 years ago

    I've got a 2004 WRX. My Mishimoto cap seems to leak, and I was looking at this as a replacement. Does this cap have any effect on the upper reservoir and it's cap? Is there some relationship between the pressures?
    • 0 of 0 people found the following answer helpful

      A:  In order to run higher pressure, you would need to run one of these caps on your radiator and one on the upper coolant reservoir. Using a lower pressure cap with this 1.5bar cap would result in a lower pressure.

      Josh P. @ RallySport Direct 3 years ago  
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  • Q: cap  wrxtuner136 years ago

    Is this ok to use on the stock cooling system on a 2010 wrx?
    • 1 of 1 people found the following answer helpful

      A:  I would personally recommend a lower pressure cap on the stock cooling system, not that I think it would cause any issues, however an upgraded radiator would be recommended to take full advantage of this high pressure cap. Thanks.

      Rick C. @ RallySport Direct 6 years ago  
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  • Q: Fitment  Manny337 years ago

    I have a mishimoto radiator, will this cap fit??
    • 0 of 0 people found the following answer helpful

      A:  This radiator cap is a direct replacement for the OEM Subaru radiators and Koyo units. I am not positive on the Mishimoto units, if the OEM Subaru cap works with that radiator there is a good chance this Cosworth unit will work.

      Tanner S. @ RallySport Direct 7 years ago  
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This Part Fits

Universal Product
This item is non application specific.
Please verify compatibility before purchase. May require some modification for proper installation.