We asked if "out perform" meant better flow than the other aftermarket heads, World explained that World and Roush don't consider flow numbers the sole indicator of a well performing cylinder head. The analogy the rep used was one of a NFL running back -while you may have the fastest back in the league, that is no indication of how many touchdown he'll score. The analogy has some truth to it in terms of how a cylinder head performs in relation to the rest of the engine and vehicle. We've seen plenty of cars running incredible ET's, with heads that don't boast the highest flow numbers in the catalog. Nevertheless, while flow numbers alone are akin to bench racing, we feel when used and compared properly, they offer very valuable information. Since we have used and worked with World cylinder heads in the past, we felt it would be an interesting article to obtain a set of Roush 200's and compare them to their predecessor, the World Sr.

Many of you are well aware that the Roush 180 and 200 heads have been appearing in magazines and even the World catalog/website for nearly a year now -yet until last month they were nowhere to be seen.

World told us that the long delay was due to constant review and changes to the design, by both World and Roush engineers. In fact as of the writing of this article only the Roush 200 has been produced and shipped to vendors. The Roush 180 (which is the new version of the Windsor Jr.) is still not ready for distribution. Both heads will be initially offered in cast iron, with plans to offer a aluminum version sometime down the line.

For those of you that are wondering why any company today would bother with an iron head, keep in mind that many racing bodies have classes that only allow iron cylinder heads. Furthermore World Castings has a huge iron foundry and thus is able to cast these heads for significantly lower costs. The cost savings are passed on to the consumer, making iron World heads the hands-down best deal on a set of aftermarket heads. Iron is heavy, but it offers significant advantages over aluminum. It will make more power due to better heat retention in the combustion chamber and less expansion. World deliberately casts their head with more material to allow for extensive porting and milling. An aluminum version is planned.

The ROUSH 200 features 2.02" intake and 1.60" exhaust valves. The chamber has been reshaped to reduce shrouding. The "RightCast" casting process has clearly resulted in a better shaped bowl and valve guide boss than the World Sr. However there is still room for 8-10% gain in flow with a minor clean up of the surfaces.

When we received the Roush 200 heads we immediately noticed considerable improvements over the Windsor Sr. Many of you may recall that we used the Windsor Sr. iron heads in our "400 HP 302" project a couple years ago. At that time we pointed out that the World Sr. head, as with any iron head, has some serious casting flash and irregularities that responded well to light cleanup with a Dremel tool and sanding rolls. The new ROUSH 200 head benefits from improvements in the casting process, which World terms their "RightCast" technology. The port shapes are consistent, and there is less flash and casting around the valve guide bosses.

In terms of actual design changes from the Sr. head to the new ROUSH head, we identified a few key ones. Along with the better casting process, the combustion chamber appears to be reshaped to reduce shrouding around the large 2.02" intake valve. We also noticed the bowls have been reshaped on the new head, and the short side radius is apparently shorter than on the Sr. head. In general the runners seem to offer a straighter shot to the valve compared to the older design.

In order to measure the gains from these changes we obviously must compare the new head to its predecessor using some sort of standard "yard stick". The two options would be to flow test both heads, or to build an engine and dyno/track test it with both sets of heads. The latter option, albeit more exciting, is also very time consuming and expensive. Considering that World claims boldly in their catalog that "The ROUSH 200cc intakes flow better than any comparable", we felt it made sense to have the heads flowed by an independent shop.

We had Gromm Racing Heads flow and analyze the new ROUSH 200 head. For those of you who are not familiar with Gromm, the San Jose,CA shop is arguably one of the nations top cylinder head specialists. They have been in business for over 30 years, porting and modifying cylinder heads for all levels of racing and street use. Considering that owner Bob Gromm has worked with every small block Ford head on the market, we felt that he would offer us a very honest analysis of the new ROUSH 200 head.

Follow along as we're sure the results will shock you. We've always been a big proponent of World heads, but what we discovered here convinced us to wait a while before committing to these heads, as World and Roush still have some work left to do.