1. It's commonly accepted that the Beta does not react well to NA mods. I've noticed from previous discussion that the 1.5l sohc Alpha Engine reacts with much better results (based on percentage power increases). Recently I've noticed (when doing online research into engine models) that the Beta is a semi-Pent Roof design, and the 1.5l sohc Alpha is a Pent Roof design. Is this difference in head design (not just with Hyundai) known to affect how well an engine will react to NA mods? My primary reason for asking is the 1.6l Alpha dohc -G4ED- (and apparently the 1.5l dohc -G4EK?-) is not Pent Roof like the 1.5l sohc Alpha, but Semi-Pent Roof like the Beta engines, and I want to know if NA mods will react closer to the Beta than to the sohc Alpha..

[ February 17, 2003, 05:21 AM: Message edited by: Frostbyte ]

 

In general, from what I have read, Pent-Roof and Hemispherical react best to N/A Mods.

For the "Semi-Pent" it really depends as to what degree of "semi" it is, along with the rest of the design of the head.

 

How does the "pent roof" and "semi-pent roof" design differ? I'm actually unsure what a "pent roof" type head would look like. I know my old escort 1.9l had a hemispherical typed head (i believe it described the way the valves sat?). I'm very interested. Can you elaborate? poke

 

The Beta reacts as well to N/A mods as any other pretty much. In Korea there are N/A cars running in the 14's. This is moderate N/A modification, and if you want to go heavy duty with quad-TB and all that, you could do better than 14.