Bowl Blending?

Bowl blending can increase HP and torque by a good bit when other parts are there to compliment the work done. The amount of power that you get will vary due to the limiting factors of the intake and exhaust systems and cams. It can be as much as 80 HP and as little as 10, but then not all can be directly claimed by bowl blending as there are the cam and the intake and carb that has a affect on this also and is worth something to the mix. As for the 1.88 valves and a stock or .030 over bore block and for the street and mild racing you can't go wrong, and with a 274 comp cams cam you definitly won't go wrong. Large valves are for high rpms and large cams and with a cam that is this small the smaller valve will flow more at low lifts with the 1.88 as velocity will be stronger also and move more air. Bowl blending will help the small valve more than the larger valve, as velocity decreases with the larger valve, thus loosing low rpm torque and HP.
But as Rumble has said that the work will vary from porter to porter even though they can look the same, also the valve job has alot to how the port will flow and where it will peak flow. But when the stock carb and manifolds are going to be used then the small valve is the key on both sides of the equation even through a good exhaust.
We have a 365 with bowl blending and gasket matching done and run stock size valves in the heads, it has a comp cams extreme energy cam .507/.510 with the heads above and a stock bottom end that has been refreshened and balanced for longivity. It runs on 87 octane pump gas the truck hit the scales at 3000lbs. and run 7.65 1/8 mi., through the stock manifolds on the intake and the exhaust with 2 1/2" and no mufflers, but a H pipe. Then we changed the manifolds and put a DP on and the truck now runs 7.40 1/8 mi. @ 96 mph still on 87 gas, so as you can see the intake and carb helped the bowl blending out some 25-30 HP more.
This engine put 354 HP to the ground and put out a good bit more than 400 HP out of the engine. The only way that the engine could do this is the fact that the heads are so efficent with the smaller valves. Larger valves loose efficiency in the heads this is why you have to run a larger cam with larger valves to create more efficiency in the heads, and turn more rpms. The efficiency with larger valves and cams comes from the turbulence created in the combustion chambers during the period of overlap at high rpms, this is why the HP is greater with large cams and heads at a higher rpm thust the engine hits it efficiency peak. But with a smaller valve and port the efficiency is lower and the need for larger componets isn't needed. Thus smaller cams and carbs. A engine is a air pump, the more efficent the pump the more air it will move and more HP it will make.
Heads need to be built for the cam and intake and exhaust used to get the most out of the engine that your useing. Some need more modifying and some less or different places. If your only useing a .480 lift cam then anything over .400 shouldn't be of concern as your only at peak lift once and have to go by the lower lifts twice. The need to make these the low lifts the strongest is very important. So when bowl blending the heads leave the short turn as tall and as sharp as possiable as this will speed the air up greatly and make it peak flow by .400 to .500 lift, thus makeing your low lifts as strong as possiable. Gasket matching will increase this by another 10-15 cfm's.
Sorry for being so winded, hope this makes it clearer.