Both parshat Bechukotai and parshat Ki Tavo contain "the tochacha", a section of the parsha with curses to befall B'nei Yisrael if they sin really badly. Traditionally, this section is read faster and in a low voice.
Where exactly does the tochacha start and end, in both parshiot?
See Kitzur Shulchan ARuch 78:4. When I read this paragraph, he lists other places in the Torah where we should read certain verses quietly. (BTW, he does not mention "quickly" anywhwere, so I'm uncertain when / how speed became a factor.) Excerpting the parts relevant to your question:
וגם הקללות שבפרשת בחקתי ופרשת כי תבא קורין בקול נמוך ואת הפסוק וזכרתי את בריתי יעקב קורין בקול רם ואחר כך הפסוק והארץ תעזב וגו' נמוך ואף גם זאת בקול רם עד הסוף ובפרשת כי תבא ליראה את השם הנכבד עד סוף הפסוק בקול רם ואחר כך נמוך עד ואין קונה
Also the curses in the portions ''Bechukotai'' and ''Ki Tavo'' we read quietly. The verse ''I will remember My covenant with Jacob...''13 we read in a normal voice, afterwards the verse ''the land also shall be forsaken by them...''14 quietly, ''And yet for all that...''15 in a normal voice upto the end. In the portion ''Ki Tavo'' ''that you may fear this glorious name...''16 until the end of the verse in a normal voice, and afterwards quietly until ''and no man shall buy you''17
So, technically, in terms of laining style, if you're referring about "normal" vs. "quiet" voice, there is a definite "start" in both situations where "start" means "low voice". In both situations, it starts at the beginning of the parsha, i.e. the start of the new Torah "paragraph". (I'm having trouble, now w/ my browser, WHen fixed, I'll try to edit in the exact verse.)
In terms of an "end", you can see that we switch voices back and forth a few times, so, you can calculate the "end" by the last silent verse, based on my understanding of the "laining" requirement in your question.
Otherwise, logically, in both cases, Behukotai and Ki Tavo tochahca are each in a single parsha (paragraph).
In Bechukotai, from the beginning of the Parasha of ואם לא תשמעו לי at 26:14 until 26:43, despite the fact that 26:42 is not a curse.
In Ki Tavo, from 28:15 until the end of the Parasha at 28:68.
My Father's (z"l) tikkun, "Encyclopedia" , includes a summary of the laws by R. Dr. Karl Applbaum, and includes the first half of verse 63 in Ki Tavo to be read in a raised voice.
This Tikkun is titled, strangely, just 'Encyclopedia' in English. In Hebrew: Tiqqun laqqorim hechadash. Also 'Entziqlopediah la-qqorim ba-Torah', kolel: chamishah chumshai Torah im ha-haftorot (sic!) u-migilat Ester. Published by 'Publishing House, 47 Canal St, NY'.
This link seems to be the same book.
