Hi , 

So since you got 51.90 percentile, your rank would be between 4 and 4.5 lakh .

The branch-wise cutoffs at LD college are: 

Branch Name                     ST ( closing rank)

Automobile Engineering         32212

Biomedical Engineering           37396

Chemical Engineering              33649

Civil Engineering                       9456

Computer Engineering               29477

Electrical Engineering                21480

Electronics & Communication   38332

Engineering

Environmental Engineering      35121

Information Technology           21771

Instrumentation & Control         39378

Engineering

Mechanical Engineering            21169

Plastic Technology                    38646

Rubber Technology                    32926

Textile Technology                     25710

Even with reservation, chances of getting admission are bleak.  

For detailed information,  check this link. 

https://www.careers360.com/colleges/ld-college-of-engineering-ahmedabad/cut-off

Hope this was helpful. 

For further queries please approach careers360.