# CIS Injectors - shrouded versus non shrouded



## Campbell (Nov 9, 2004)

Hi,

I have a 1.8L solid lifter head that was an early one - non shrouded. I have read in the digi/CIS head posts that the consensus is there is no performance difference between shrouded and non shrouded injection. 

My question is - does it matter if the injector end "cap" is left on in a non shrouded head? does it need to be removed? I would like to be able to switch motors; one has a shrouded head the other doesn't and not have to switch injectors. 

Thanks


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## WaterWheels (Aug 14, 2005)

Whether there is or is not any performance difference I don't think was ever really tested to find the exact answer. I can't ever recall seeing or hearing of back to back dyno testing being done and for sure have never seen any results posted. That said, I doubt the difference is all that much but the finer the misting the better the burn so there should be at least some difference.

Swapping cylinder heads is not like changing sparkplugs or swapping valve covers. If you are going to take the time and spend the money to swap heads the minor cost of having a set of the correct injectors really seems minor to me. "Early" non-shrouded head if I'm not mistaken would be a 1.6L or 1.7L head. I believe, could be wrong and would have to check, that with the introduction of the 1.8L both the increased valve spacing and the beginning of air shrouded injectors began. Yea, the first ones were mechanical followers but still had air shrouding. You don't say anything about the "other" head so I really can't say much as to what could be better.

If you can remove the "end cap" or not depends on just what you have for cylinder heads. Some claim using the injectors without these installed in a setup that was designed for them causes no issues. I have never seen any test done on this topic either, but removing the "top hat" opens the area that air has to pass through (they reduce the area and create a kind of venturi which speeds up the air movement). Logic tells me that more air would be allowed to enter causing a leaner mixture, maybe even unbalanced , and maybe cause a slight miss too. As no back to back tests were done that I know of I can only go by what some people have written. Some say it causes no problems and some say it does have an effect on things. I for one believe the effect (bad) side of the house.


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## MzerMK2 (Jul 5, 2011)

*CIS Injectors*

Ive used injectors without the "top hat" with no problems ...I think that it may work on the 'vortex' (if you will) alil but i think most the reason they were there to seal the vacuum for the 'cross flow affect' to help keep the injectors cooler...cooler fuel more power...this is why the newer ABA's And newer models the intake was moved from over the exhaust manifold to the front...


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