Jim I know you don't want to turn much rpm over what your motor does now. Your goal has always been to stay under that 5500 rpm ceiling. That's fine and you've gone as fast as anyone else with your strict guidelines.Alot of good tuning got you there and intelligent selections. I know you've gone even faster with yours in a different configuration. We all have goals and what we want out cars to do, look like. Mine is to keep a Shaker on the motor and go fast on pump gas and be streetable, I don't think there are too may out there that can stay up. I probably could pick up with a Victor, but that looses my main guideline. I'm not arguing that the KREs ran slower on your car or that yes increasing rpm range you could have gone even faster. That wasn't your goal and they didn't meet your needs.
Jim you may not have done it as a head test BUT I think almost EVERYONE here read into your results that the 185cc ports were why it ran slower, and because of their slower velocity and no other variables were possible. "As a result of the loss of low and early mid range power due to the larger ports on the KRE heads" Right there it says the big ports are the only potential problem! It was very strongly implied that any motor with similar cam range(within 3 degrees @ 0.050), D port heads, intake, carb would also NOT benefit from the change using the bigger ports because yours did not. Cliffs is as close to your combination as possible other than not the same exact heads with the same exact flow. OK cam was 3 degrees different @ 0.050. Which is virtually impossible unless we use CNC ported iron heads.Hence the comparison, and discordant results, and no loss in bottom end feel. In fact Cliff's less ported heads should have had smaller ports than yours and gone even slower. Other folks are also going faster. So it is not just the port size for every car! Most other ported D ports that flow similar to yours are going to be closer to 180cc so probably less velocity, so no way are anyone else's going to perform the same as yours using the same logic.
Variables -Put a 6X-4 head next to a 6X-8 and a head gasket against both. They aren't the same chamber. So if your before ported iron and after D ports were different castings we have the potential for a variable. Recent magazine tests even question our 1 point difference in aluminum vs iron compression. But no one questions the loss of heat and HP in an aluminum head vs iron head, unless barrier coated at the saem compression. So that is one vairable on yours eventhough you tried to keep the compression a non variable. So even different castings are a true variable. You can't striclty say the port size was the factor on yours!teh different port shapes in even the ported iron heads much less the KRE head's different shapes add a variable to the cylinder filling independent of the port cc! The chambers are an extention of the port and affect that also and are different so another variable.
I go back to Pontiacs round port vs D port 455 port size which you have never even commented on. How did Pontiac keep their rpm range similar if 30cc impacts them that much, or did the increased flow or different chamber do it? The same difference in the KRE and your heads and fewer other variables. What's the reasoning here?
OK we will approach the concept small ports flowing the same as big ports. You will know all of this as well as I, as much as you read, it's not that simple! or I guess I'm just really dense!
Velocity theoretically would be increased, BUT if it too much vleocity we make fuel fall out of suspension, packing the cylinder with air and less fuel/air combination needed for HP. Most head gurus, Vizard included, feel getting close to sonic speed velocity is BAD. What is the velocity in a small port on a 465ci motor when running? Will ALL the air in the port be able to make all the short turn at the higher velocity? Or will some of it collide or tumble making flow go backwards, easily heard on the flow bench. Vizard has mapped velocity in SBC ports and reccommends porting more in those areas-do we know that for a Pontiac port? Which head's port? What is the velocity in your ports and in what areas? As I've stated before I'll be we don't have a map for any of our heads like Vizard has done. Do you know the velocity was slower over more of the KRE port than your 6X port? That's what we are assuming based just on port cc.
Why are the NASCAR, Pro Stock etc big guys finding even identical flowing , identical sized ports run different? They must run the same but they don't.That's where they go to the wet flow bench. Tom S even talked of having his RAVs wet flowed. Just the slightest difference in port shape chamber shape adds a variable into that and they can see it on the wet bench. On hand porting I'd bet even variables between different cylinders.
I had 4 totally different cams in the RAIV 400 and ALL ran identical to the 0.01 times & mph, only one killed the streetability and increased rpm range needed, a big solid. Different variables were at work.The cam was one, the exhaust header another.
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