That brings me to my question and I apologize for the book! We are considering having our motor dyno'd for 2 reasons. One, I'd like to run the motor in and 2 I'd like to get the right jets in the car for our plate and rpm range. I see the posts about getting the dyne done. Apart from tuning the carb, is there much more that can be done? I heard about exhaust tuning but 600 tells me that they have seen cery little difference with differnent length exhausts. The only advice is to pull the collectors out as far as legally possible.
For carb flowing, that makes me nervous. I had a conversation with our tech guy and he tells me they see polished intake castings and slight bore modifications. Both illegal. And I certainly don't want that. So what is the advantage that can be gained there? Is sending the motor to a third party better than having 600 dyno it? I don't want to break the bank, but 20% is huge if it's real
THere is more to dyno tuning than the carb. 600 may be correct in that they see very little difference, but if that difference is .3 HP, and then you gain .2-.3 in the other areas, along with some bigger gains with carb, at the end of the day you have significant HP increases in a 13 HP red plate engine! Its all about getting alot of little things right, and getting the most out of that one particular engine.
Also, 600 dyno's indoors, in a controlled environment ( i.e. temp, humdity, etc. stays fairly stable due to Heating & A/C, possible de-humidifiers, etc. within the building.) Thats not what we race in, and sometimes results differ when you dyno to open atmospheric conditions with the temp at 90 and humidity at 65% for ex., as compared to more controlled conditions.
As for flowing/blueprinting a carb, that does not mean the carb is machined, polished, ground, etc. It means that it is flowed on the flowbench, and then parts are changed, etc. to achieve the maximum air flow. Believe it or not, the way a carb is assembled can affect its airflow. Then the fuel ratio needs to be matched to the airflow for that particular carb. This is fine tuned on the dyno, as the air/fuel ratio needed is determined ultimately by the specific engine's intake runners, heads, volumetric efficiency, etc. It can only be found on a dyno, unless you choose to break engine seals and cheat-up the engine.
All I know for sure is that engines come off the dyno with more power than when they went on. The only exception is when the engine is worn, and the dyno won't do a ring job or a valve job! It will tell you that the engine is a dog and needs to be rebuilt, or that the engine is capable of winning. This is quite substantial in and of itself, since you can now rule out engine as the problem, and concentrate on handling, tires, or other issues. Before you can fix what's wrong with a car, its important to verify all the things that are right, and thus eliminate those items from the list of things you suspect as a problem.
For example, its easy to wear out a set of tires, spend money on gas to the track, pit passes, track rental for testing, etc. trying to find speed, when the problem all along was a weak engine. I like to rule out engine, carb and tires as a problem before I ever get to the track. I can rule gearing out pretty quick with the tach and dyno sheet. That only leaves set-up and driver, so I know where to throw the tool box when at the track!
Just my .02 worth.