It's a rainy morning and to piss off those who don't like reading my BS or even like seeing it on here because they have a hard time reading and comprehending and having some fun writing here are some thoughts from watching racing a lot of years. 
I hope it's a fun read.
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I don't separate a corner into entry, apex and exit though there is still entry, a moving/changing apex and an exit dirt oval racing. I seperate the corner into four functions instead of parts:
1. The moment of turn in or the start of the corner. Usually you'll hear it's the LF that starts you into the corner but anything driver input, the bank of the track, changes in grip, etc., all can get you started into the corner. The start of the corner is something which causes the initial weight transfer from left to right and back to front, which is needed during the corner.
2. Next comes the needed control of weight transfer to the right which will cause your tires to operate for the next phase or function in the corner which is maintaining momentum. I often say and explain that if two racers on a track have identical equipment and potential with all other things being equal the driver who can maintain the most momentum between the moment of turn in and the start of acceleration will be the fastest.
The momentum portion of the turn is a must to be fast. Enhancing it is what always has lead to the old saying of "slow down to go fast". It is the portion of the turn which includes what left and right racings calls the apex and if used properly 'cannot' be used for acceleration.
If you get on the gas beyond what is needed to set your momentum speed or remain on the gas beyond your limit of grip during this part of the turn, it will mean a loss of over all speed. If you can accelerate during this part of the turn it means you have more grip that can be used to maintain additional momentum. Instead of the pedal to the metal you should be using the additional available grip to maintain more momentum.
3. Once you have completed maintaining momentum which may have been very short or though a long portion of the turn depending on track configuration and how your choosing your line on the track, the start of acceleration begins. It's the start of acceleration which determines the start of exit and the start of exit is not the completion of a turn but 'another' turn. The start of acceleration should be taken and considered using items 1 and 2 above no matter how short, quick or gradual you start your acceleration. It's also often said turn exit is determined by entry. Yes it is with the addition of how your maintaining momentum portion of the turn sets you position on the track for the start of acceleration. If you have set entry and maintaining momentum to include enough of the over all turning needed to complete the overall turn, your transitioning to acceleration while exiting will be mild because you do not have excessive turning to do while exiting.
4. The final phase or function needed is to accelerate. If you have maintained momentum and completed enough of the overall turning during 1 and 2 you will be able to maximize acceleration based on how little turning you have to do while accelerating.
How fast you can come off the corner depends on how long a straight your position on the track gives you. It also depends on if your acceleration can take advantage of gravity traveling down the track. And it most importantly depends on how much of the over all turning at an end of the track or each of the four corners you have left to do while accelerating. The more turning you have left the less you will be able to accelerate.
If written correctly all of the above should lead to thoughts of how usually through most of the physical distance at each end of the track you cannot accelerate. If you can't accelerate then you must be either slowing down or maintaining momentum. Fast becomes who can maintain the most momentum and best put themselves in a position to accelerate in the straightest line. The only trade offs to 1, 2, 3 and 4 above are racing trade offs where to gain position you must lessen your use of one of the above. A slide job which gets you from point A to B quicker but causes you to also slow down because you did not complete enough turning before needing to accelerate is a good example.
There is one and only one possible option beyond the go pedal to increase your speed during the momentum portion of the turn. It occurs when you use the grip available after initial turn in not to maximize momentum speed but to change your position on the track. If you increase your turning you or tighten your turn while maintaining momentum, the additional turning will increase over all speed the same as an ice skater spinning increases speed when they pull their arms in tighter. Those viewing result when well done will be not only seeing what's racing accelerate down the bank of the track but sort of shoot down the bank of the track. You can also use tightening a turn to increase your momentum speed depending on track conditions by how tight or tightening of the turn you make the or make an extended initial turn in. It's what your often seeing when you see something sort of accelerate into the turn and it best shows itself asphalt oval racing. It's all about how a skilled driver can choose to use the momentum maintaining portion of all turns to both position themselves for exit and control their ability to accelerate on exit.
